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Full text of "Handbook for Railway Steam Locomotive Enginemen"

BRITISH TRANSPORT COMMISSION 



Handbook 



for Railway 



Steam Locomotive 



Enginemen 



1957 






Published in 1957 by 

British Transport Commission 

and produced at The Baynard Press 

by Sanders Phillips & Co., Ltd. 

London, S.W.9 



All rights reserved 



B.R. 33014 



Printed in England 



FOREWORD 

The object of this book is to help enginemen to become 
proficient in their duties. In particular, it will be beneficial 
to cleaners and firemen in their preparation for promotion. 

It is written with the object of giving a general 
description of locomotives and the principles involved 
in their construction and operation within the compass 
of a book of reasonable size. 

The book deals with the steam locomotive, but it is the 
intention to follow it in due course with a similar publi- 
cation dealing with other forms of motive power. 

It should be emphasised that no one can become a 
proficient railway locomotive engineman merely by 
reading books, however good they may be. The highest 
proficiency, however, can only be achieved by studying 
the subject from all angles and putting into practice the 
knowledge and precepts gained from text-books. 

The increased cost of fuel, together with the importance 
of punctuality, makes it essential that you should strive by 
all the means in your power to achieve the fullest know- 
ledge of your work, and close study of this publication is 
one way which will assist you to do this. 



R. F. HARVEY 

Chief Operating and 
Motive Power Officer 



CONTENTS 

foreword 

Colour Identification Chart 9 

List of Diagrams 10 

SECTION I 

General Page No. 15 

Introduction: Notices and Rules: Cleaners: Firemen: 
Drivers: Working Trains: Engine Disposal: Turning the 
Locomotive. 

SECTION 2 

Combustion Page No. 23 

Composition of Air and Coal : What happens in the Firebox : 
Principles of Good Firing: Preparing the Fire: Starting away 
with the Train : Firing on the Journey: When the Regulator 
is Closed: Blowbacks: Firing of Shunting Locomotives: 
Size of Coal: Use of Fire-irons: Use of Deflector Plate: Use 
of Dampers: Working of Injector. 

SECTION 3 

Transformation of Heat into Power Page No. 34 

Heat: Temperature: British Thermal Unit: Conduction: 
Convection and Radiation: Steam Generation: Relation of 
Temperature to Pressure: Saturated Steam: Superheating. 



SECTION 4 



The Boiler: Boiler Mountings and Details Page No. 37 

Types of Boilers and Fireboxes: Smokebox: Self-cleaning 
Smokebox: Superheater: Blast Pipe: Brick arch: Firehole 
Door: Drop Grates and Rocking Grates: Hopper Ashpans: 
Boiler Mountings: Safety Valves: Water Gauges: Pressure 
Gauges: Fusible Plugs: Washout Plugs: Handhole and 
Mudhole Doors: Blower and Valve: Regulator Valve: 
Vertical Side-type Regulator: Horizontal Dome-type Regu- 
lator: Horizontal Regulator— Smokebox type: Double-beat 
Regulator: Multiple Valve Regulator: Injectors: Exhaust 



Injectors: Steam-controlled Exhaust Steam Valve: Auxiliary 
Shuttle Valve: Steam-controlled Water Valve: Possible 
causes of Injector Failures: Blowdown Valve: Carriage- 
warming Valve: Cab Fittings. 

SECTION 5 

Valves and Pistons Page No. 80 

Reciprocating and Rotary Motion: Distribution of Steam in 
Cylinders: The Slide Valve: Lap and Lead: Eccentric: 
Angle of Advance: Relative Motion of Valve and Piston: 
Indicator Diagram: Piston Valves: Inside and Outside 
Admission of Steam: Long Travel Valves: Piston Head: 
Cylinder Cocks: Anti-vacuum Valves: Crank Positions: 
Methods of Testing: Failures. 

SECTION 6 

Valve Gears Page No. 98 

Stephenson's Link Motion: Walschaert's Valve Gear: Rotary 
Cam Poppet Gear: Valve Gear Failures: Running Gear 
Failures. 

SECTION 7 

Lubrication Page No. 126 

Various Types of Motion: Methods of Lubrication: Lubri- 
cation of Axleboxes: Mechanical Lubricators: Hydrostatic 
Lubricators: Cylinder Lubrication: Atomiser: Trimmings. 

SECTION 8 

Brakes Page No. 142 

Automatic Steam and Vacuum Brake: Solid and Annular 
Jet Ejectors: Steam and Vacuum Brake Valve: Automatic 
Vacuum Brake (former G.W.R.): Relief Valve: Drip Valve: 
Vacuum Brake Cylinder: Ball Release Valve: Automatic 
Vacuum Brake: Automatic Westinghouse Air Brake: Brake 
Tests: Brake Failures. 



SECTION 9 

Automatic Train Control 

SECTION 10 

The Rule Book 

Index 



Page No. 182 

Page No. 192 
. . . 195 



COLOUR IDENTIFICATION CHART 



SATURATED STEAM 



SUPERHEATED STEAM 



EXHAUST STEAM 



ATMOSPHERIC AIR 



COMPRESSED AIR 
Higher Pressure 




COMPRESSED AIR 
Lower Pressure 




VACUUM 




OIL 





WATER 



FEED WATER 



WATER AND STEAM 



AIR AND STEAM 



The above colours apply to all diagrams except 
where shown otherwise 



A* 



10 



DIAGRAMS 



Fig. No. 



1 

2 

3 

4a 

4b 

5 

6 

7 



9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 

20 

21 

22 

23 

24 

25 

26 

27 

27a 

28 

28a 



Page No. 

23 



Diagram showing coal constituents 

Diagram showing excess air, heat loss and smoke 

Firebox showing correct fire 

Firebox showing incorrect lire 

Firebox showing incorrect fire 

Effect of size of coal 

Incorrect position of baffle plate 

Sectional view of boiler 

Sectional view of boiler with superheater 

Sectional view of boiler with thermic syphon 

Sectional view of boiler with smokebox regulator 

Typical self-cleaning smokebox 

Jumper blast pipe top 

Arrangement of double blast pipe 

Arrangement of rocking grate 

Arrangement of hopper ashpan 

Safety valve 

Water gauge 

Water gauge— top and bottom cocks coupled 

Water gauge with test cocks 

Regulator valve. Vertical dome type 

Regulator valve. Horizontal dome type 

Double-beat-type regulator valve 

Simple injector 

Injector combining cone with hinged flap 

Injector combining cone fitted with movable portion 

Live steam injector monitor type 

Exhaust injector arrangement and control diagrams 

Class " H " 62-63 

Exhaust injector Class "H" M 

Exhaust injector Class "J" , c 

T> t. ■ • 66 

Exhaust injector Class "HJ" 67 



26 



30 



38 
39 
41 
42 
43 
45 
45 

47 

48 

49 

50 

51 

52 

54 

55 

55 

56 

58 

59 

60 



11 



Fig. No. 



Page No. 



29 Exhaust injector Class "K" (Improved) 68 

30 Continuous blowdown valve 70 

31 Arrangement of cab fittings, standard locomotive 71 

32 Diagram showing distribution of steam on one side of the 
piston for a double stroke 81 

33 Section slide and piston valve 82 
33a Isometric view of slide valve and piston valve 83 

34 Valve events for one revolution of wheel 84 

35 Eccentric crank and return crank 85 
35a Position of eccentrics 87 

36 Piston head: B.R. standard locomotives 88 

37 Steam-operated actuating valve and cylinder drain cock 89 

38 Anti-vacuum valve mounted on steam chest 9 1 

39 Anti-vacuum valve mounted on superheater header 91 

40 Least-effort position of crank 93 

41 Stephenson valve gear with outside admission piston 
valves direct motion 99 

42 Stephenson valve gear with rocking shaft — W.R. 
2-cylinder locomotives 100 

43 Stephenson valve gear — valve lead 101 

44 Walschaert valve gear 102 

45 Arrangement for Walschaert valve gear for inside and 
outside admission valves 103 

46 Walschaert valve gear — former G.W.R. 4-cylinder 
locomotives 105 

47 Walschaert valve gear — former. L.M.S.R. 4-cylinder 
locomotives 106 

48 Walschaert valve gear— (Gresley) former L.N.E.R. 
3-cylinder locomotives 107 

49 Combination lever arrangement inside and outside 
admission valves 108 

50 Arrangement of valve gear— former S.R. West Country 
class locomotives 109 



12 



Fig. No. 



51 



Page No. 



General arrangement of British Caprotti valve gear, 
outside drive 

52 (General arrangement Caprotti valve gear drive taken 

53 \from leading axle 112-113 

54 British Caprotti valve gear section through inlet and 
exhaust valves 

Worsted trimmings. Details of preparation 
Silvertown mechanical lubricator 
Wakefield mechanical lubricator 
Detroit hydrostatic side feed lubricator 
Arrangement of atomiser lubrication 
Connecting rod lubrication 
Fountain-type axlebox lubricator 
Types of roller-bearing axleboxes 
General arrangement of vacuum automatic brake on 
engine and tender. B.R. standard arrangement 
S.S.J, ejector 

Driver's brake application valve. B.R. standard 
locomotives 

Vacuum-operated graduable steam brake valve (Mark IV) 147 

Driver's brake valve 149 

Brake arrangement on engine and tender— former 
G.W.R. locomotives 

Vacuum pump — former G.W.R. locomotives 
Retaining valve — former G.W.R. locomotives 
Arrangement of vacuum brake on engine and tender 
— former L.N.E.R. locomotives 
Dreadnought ejector 

Working diagram of Dreadnought vacuum ejector and 
driver's brake valve 

Working diagram of S.J. vacuum ejector and driver's 
brake valve 



55 
56 
57 
58 
59 
60 
61 
62 
63 

64 
65 

66 
67 
68 

69 

70 
71 

72 
73 

74 



111 



114 
127 
130 
132 
134 
135 
136 
137 
139 

144 
145 

146 



150 
151 
152 

154 

155 

156 



158 



75 Brake arrangement, ex-L.N.E.R. A.3 Pacific locomotives 162-3 



13 



Fig. No. 



Page No. 
164 



76 Vacuum brake cylinder, C. Class combined 

77 Vacuum brake cylinder (combined) slipping-band type. 
B.R. standard for coaching stock 165 

78 Vacuum brake separate cylinder, C. Class 164 

79 Vacuum brake separate cylinder, F. Class 166 

80 Diagram of Westinghouse automatic brake 167 

81 Westinghouse brake air compressor governor 168 

82 Driver's brake application valve 169 

83 Feed valve 168 

84 Triple valve (ordinary) 171 

85 Triple valve (improved) 173 

86 Westinghouse brake diagram; automatic brake on 
engine and tender with proportional valve 174 

87 Automatic train control— former G.W.R. system 184 

88 Automatic train control— L.T. & S. (E.R.) system 187 

89 Automatic train control — British Railways system 189 



SECTION 1 
GENERAL 



15 



Introduction 

The Junior Engine Cleaner who has started his career to become 
an Engineman on British Railways is expected to take an interest 
in locomotives, to fit himself to take charge of them when he is 
promoted. Whilst working as a Cleaner he must make himself 
acquainted with the general arrangement of the various types of 
locomotives and learn the names of the various locomotive parts, 
e.g. frames, cylinders, steam chests, wheel arrangements, boiler, 
firebox, smokebox, safety valves, etc. He will receive tuition from 
Chargeman Cleaners, Firing Instructors and Inspectors. He should 
take the opportunity to supplement the information in this Hand- 
book by asking questions of Fitters, Drivers, Firemen, Foremen, 
Inspectors, and by attending Mutual Improvement Classes, and 
lectures in the Mobile Instruction Trains, where provided. 

Notices and Rules 

In addition to obtaining a knowledge of locomotives, it is essentia- 
that he should become fully acquainted with the Rules and Regulal 
tions which apply to him. 

A study of the Permanent Notices and Rules 1 to 16 in the Rule 
Book will instruct him in his personal conduct and safety, and a 
knowledge of the following rules will prepare him for the time when 
he will be called upon to act as a Fireman : — 



Rules Nos. 34-49 
Rules Nos. 50-51 
Rules Nos. 55-56 
Rules Nos. 126-8, 141-3 
Rules Nos. 178-181 



Fixed Signals 

Hand Signals 

Detention of Trains 

Working of Train 

Protection of trains stopped 
by accident, etc. 

He should have a knowledge of "Prevention of Accidents" as well 
as the proper procedure of coupling and uncoupling. 

Cleaners 

Before a Cleaner can be allowed to act as a Fireman he is required 
to show a satisfactory knowledge of the following subjects: — 

(i) General description of a locomotive, i.e. names and uses of 
principal component parts. 



16 



(ii) General knowledge of Rules and Regulations particularly 
applicable to: — 

Hand and fixed signalling. 

Protection of trains and opposite or other lines. 

Locomotive equipment. 

(iii) Method of firing a locomotive, general duties and respon- 
sibilities of a fireman. 



Examinations 

A careful study of this Handbook will assist Firemen to become 
proficient in their duties and prepare them for their examination 
to pass as Drivers, which will be held on the following subjects: — 

The technical examination to act as Driver, which will be carried 
out by a Motive Power Inspector, will comprise an oral and practical 
examination : — 

(a) Oral Examination 

The candidate to be examined in the following subjects: — 
(i) Knowledge of locomotive, 
(ii) Knowledge of mechanism of continuous brakes, 
(iii) Method of dealing with locomotive defects, 
(iv) Knowledge of rules and regulations, 
(v) Knowledge of the various types of signals, their use and 

the rules relating to the reading of signals, 
(vi) Knowledge of the making out of reports. 

(b) Practical Examinations 

The Examiner will give attention to the following points: — 
(i) Care and manipulation of locomotive, 
(ii) Attention to boiler and fire, 
(iii) Attention to signals and judging distances, 
(iv) Attention to rules and regulations, 
(v) Knowledge of locomotive parts, 
(vi) Making and using trimmings, 
(vii) Care in and attention to oiling, 
(viii) Examining locomotive and reporting defects, 
(ix) General knowledge of automatic and steam brakes, 
(x) Ability of examinee to change a boiler water gauge glass. 
It must be clearly understood that the questions and answers 
printed in this book are not necessarily identical with those which 
will be asked at the examination. 



ENGINEMEN'S DUTIES 



17 



Firemen 

Good timekeeping is an essential part of a Railwayman's job. 
After signing on duty at the right time and reading the notices, the 
Fireman should then join his engine. His first duty is to examine the 
water gauges and notice the steam pressure. If the water level is 
satisfactory he should give attention to the fire, level it down and 
raise the steam pressure, to enable the injectors to be tested as early 
as possible. 

He should satisfy himself that the fusible plugs and tubes are 
satisfactory and that the brick arch and firehole deflector plate and 
protection ring are in good condition, also the smokebox door is 
screwed up tight. 

It is the Fireman's duty to draw tools and equipment from the 
Stores, where tools are locked up, and to clean and trim the lamps, 
where required to do so. 

He must make sure that the required number of flags and 
detonators are carried and, where these are contained in a sealed 
canister, ensure that the seal is intact and the "date" indication 
correct. 

Careful preparation of the fire is half the battle. He should start 
by spreading the fire over the grate evenly with a fire-iron, running 
this over the bars to clear the air spaces. 

Some classes of coal require the use of broken firebrick, limestone 
or shingle, which prevents clinker adhering to the firebars. This must 
be thrown on the bars before spreading the fire. 

The fire should be built up by adding small quantities of coal. 
Large coal must be broken to lumps little larger than a man's fist. 
This exposes to the action of the fire a greater surface of the fresh 
coal than would be the case if large pieces were used. 

Firing should continue at intervals, giving each charge of coal 
time to ignite properly, until a bed of fire, well alight and suitable for 
the class of train to be worked, is obtained. The damper should be 
open and blower carefully applied sufficiently to avoid smoke. 

He should be particular to sweep the front platform and the foot 
framing clear of all loose ashes and sand which would, if not 
removed, present an untidy and unkempt appearance, and, moreover, 
would blow into the motion and cause increased wear. 

He should satisfy himself that the ashpan has been cleaned and 
that the dampers are in working order. The sand boxes must be 
filled, the fire-irons properly stowed and the coal safely stacked on 
the tender. 



18 



He should see that the cab, boiler fittings and tool boxes are kept 
clean; it must be remembered that a good Fireman takes a pride in 
the cleanliness of his footplate. When cleaning gauge glasses and 
protectors, he must make sure that the protectors are in good con- 
dition and that they are secured in the correct position. It is 
important that all pressure is released from the gauge glass before the 
protector is removed and that the protector is replaced before 
pressure is restored. 

Any difficulties experienced or defects noted during preparation 
must immediately be brought to the notice of the Driver. The Driver 
is in charge of the locomotive and the Fireman's duties are carried 
out under the Driver's control and supervision. 

Drivers 

After signing on duty the Driver should read the current notices, 
sign for those which require it, and obtain his working instructions 
and any special instructions affecting his workings. 

On arrival at the locomotive, the Driver should test the water 
gauges, satisfy himself that the fusible plugs and tubes are tight, 
note the condition of the fire and steam pressure, and see that the 
Fireman is correctly attending to his duties. 

He should see both injectors tested and himself test the brake and 
sand gear, and, if any defects are observed, take steps immediately 
to have them remedied. 

In making his examination and oiling of the locomotive, the Driver 
should have a definite system and always work to it. He should be 
acquainted with the differences in the layout of the various classes 
of engines with which he may have to deal in the course of his duties. 
By commencing at the same point, and always in the same order, he 
will deal with the various parts methodically. 

The water pick-up gear, where fitted, should be tested and oiled 
and great care taken to see that the scoop is in the "up" or "out" 
position and the handle secured to avoid any damage being done 
when the locomotive is moved. 

When preparing a locomotive fitted with steam heating apparatus, 
during the carriage-warming season he should see that the flexible 
hosepipes and connections are in good order, the apparatus should 
then be tested by opening the cock at the tender end (or the cocks at 
each end on engines so fitted), next open the steam valve to discharge 
all condensation from the apparatus, close the cocks and see that the 
correct heating pressure can be obtained. If the regulation pressure 
cannot be obtained or is exceeded, the matter must be fully reported 
on a repair card and the defect remedied. 

On engines fitted with rocking grates, drop grates or hopper 



19 



ashpans the Driver should satisfy himself that the operating handle 
is in position, that the catches are secure and that the ashpan hopper 
doors are closed. 

During the time an engine is being prepared, care must be taken to 
see that the safety precautions have been carried out and, before 
entering the motion, that the hand brake is hard on, the reversing 
gear in mid position and the drain cocks open in accordance with 
instructions contained in Permanent Notice B.R. 32709/1. 



Working Trains 

A Driver should have a thorough knowledge of the route over 
which the train is required to travel and have signed his Route 
Knowledge Card to this effect. If he is not fully conversant with any 
section he should obtain the services of a competent conductor. 

The Driver must have with him on his engine a complete set of 
lamps, not less than 12 detonators and two red flags and such tools 
as may be prescribed by the Motive Power Superintendent. He is 
responsible for seeing that the prescribed lamps, etc., are exhibited 
and in good order and lighted when necessary. He must keep a good 
look-out when the engine is in motion, sound the engine whistle when 
necessary, especially as a warning to persons on the line and 
frequently when passing through tunnels, see that the proper signals 
are exhibited, observe and obey all signals, and all speed restrictions, 
have his Fireman disengaged when passing signalboxes, start his 
train carefully and proceed along the proper line, stop his train with 
care, paying particular attention to the state of the weather, the 
condition of the rails and the gradient as well as the length and 
weight of the train. During foggy weather he must keep a sharp 
look out for Fogsignalmen and when the signals cannot be seen 
assume that the signal is at caution or danger and proceed cautiously 
or stop immediately as the case may be. He must also observe the 
instructions contained in Rules 126 and 127 in addition to other 
instructions regarding the working of trains contained in the Book 
of Rules and Regulations, the General, Regional and Sectional 
Appendices and the Regulations for the working of the Vacuum 
Brake. 

The Driver should always endeavour to operate the locomotive in 
the most efficient and economical manner consistent with the work to 
be performed by the use of the regulator and reversing gear. 

His Fireman must, when not necessarily otherwise engaged, 
observe all signals and keep a good look-out all the time the engine 
is in motion. He must avoid waste of steam and water from injectors, 
strict attention being paid to the avoidance of unnecessary blowing 



20 



21 



off and creation of excessive smoke, and take care not to deposit 
engine ashes at other than the appointed places. 

ENGINE DISPOSAL 

Firemen 

Towards the end of the run the fire must be levelled and worked 
down as low as possible to avoid arriving on the shed with a large 
amount of fire in the grate. 

Upon arrival on the shed, and after reporting the arrival of the 
engine, coal will be taken and the tank filled with water, and the 
engine placed over the ashpit. After taking water the tank lid must 
be closed. Care must be taken during coaling to avoid spillage, and 
prevent damage to coaling apparatus by inadvertent movement of 
the engine. 

On the ashpit the Fireman will, when required, empty the smoke- 
box (locomotives fitted with self-cleaning smokeboxes will be dealt 
with in accordance with instructions). The fire will be withdrawn or 
cleaned as necessary and it is important to clear the ashpan thoroughly 
Locomotives fitted with rocking grates and hopper ashpans will be 
dealt with in accordance with instructions posted at the Depot. Care 
must be taken to see that the hopper doors are left closed and secured 
and that the operating lever is replaced in position on the footplate. 
It is essential to close the dampers and firehole door after the fire 
has been withdrawn, and the blower valve shut off to prevent the 
entry of cold air into the firebox, which would set up contraction 
stresses in the boiler plates, stays and tubes. (For the same reason 
the locomotive should, when necessary to move in own steam be 
worked as lightly as possible to reduce the quantity of cold air which 
would be drawn through the empty firebox and tubes.) 

The Fireman should collect, check and clean all tools and equip- 
ment for return to the stores or lock them up on locomotives where 
keys are provided. If any item has been lost or damaged he should 
inform the Driver, who will report the facts when signing off, and the 
Fireman should draw the Toolman's attention to the discrepancy 
when handing over the equipment. 

Before leaving a locomotive after stabling, the boiler should be 
filled with water to a height of three-quarters of the gauge glass and 
the locomotive left secure with the hand brake hard on. 

Drivers 

Whilst the Fireman performs his disposal duties the Driver will 
make an examination of the locomotive; he should proceed 
systematically as when preparing and will book all known defects 



If necessary the Driver will make out a ''Repair" card which 
should be written in ink or indelible pencil: it should be clearly 
filled in and as much detail as possible given concerning the defect. 
He should avoid reporting more than one item on one line of the 
card, each item to be clearly defined. He should be particular to 
report all blows and ascertain by test if necessary, during his 
examination, whence they originate. 

He should note whether all valve spindles and piston rods and 
other points are properly lubricated, and examine all slide bar 
bolts, big and little ends, etc. Symptoms of defects noted whilst 
running should be properly reported. It must be borne in mind 
that the examining Fitter or the Fitter who will do the repair work 
may find the engine out of steam when he gets to it. The report 
should therefore convey to him as far as possible what is wrong 
so that he will be able to go straight to the defective part and not 
waste time examining parts that are working correctly. 

If there are no known defects a "No Known Defects" card must 
be made out. 

Before the locomotive is left, care must be taken to see that it is 
left secure with the regulator fully closed, reversing screw or lever 
in mid gear, cylinder cocks open, hand brake hard on and the 
blower valve closed. 

Turning the Locomotive 

An engine to be turned should always be taken on and off the 
turntable slowly and brought to rest easily to avoid straining the 
mechanism and the structure of the turntable. The competent 
Driver knows exactly where to stop, having previously noticed what 
part of that type of engine comes opposite a certain part of the 
turntable or to a landside mark as the case may be, so that he is 
able to stop quickly and easily in the desired position without 
waste of time re-setting. During the operation of turning, the 
hand brake must be screwed hard on, the reversing screw or lever 
in mid gear and the cylinder drain cocks opened. 

Hand-operated turntables should always be pushed round and 
never pulled because, when pushing, the man operating the table is 
behind the bars so that if he should fall or slip the table will move 
away and leave him clear. A man pulling on the bar, however, 
might be injured if he slipped or fell because the bar would pass 
over him. 

When operating a mechanically propelled turntable, in addition to 
the usual precautions taken to prevent movement of the engine, the 
propelling mechanism of the turntable must be handled carefully. 



22 



If of the vacuum tractor type, the starting valve must be opened 
slowly to minimise the shock to the gearing, care being taken to see 
that the catches are out before the tractor is started. The table must 
never be stopped by forcing the catches in. The tractor must never 
be used as a brake to stop the table by reversing. In all cases the 
tractor should be shut down at such a point that the table will roll 
to rest in the desired position of its own accord. The large ejector 
should always be used to create ample power to operate the tractor 
Engmemen called upon to work any kind of machinery must take 
certain elementary precautions in their own interest and that of 
others. They should take every opportunity to make themselves 
familiar with the different types of turntables and mechanised 
coaling plants and their controls. 

A Fireman or a Passed Cleaner acting as a Fireman is under the 
control and supervision of the Driver upon whom falls the respon- 
sibility of assisting in training him in the early stages of his career 
By tactful and careful instruction the driver, by recalling the time 
when he himself was in a similar position and acting on his own 
experiences, will have considerable influence which will reflect 
credit upon him, in addition to making each working day satisfying 
to both, in the knowledge of a job well done. 



23 



SECTION 2 
COMBUSTION 



Composition of Air and Coal 

Combustion takes place when coal burns in air, and correct 
combustion can only be obtained by bringing together the right 
amounts of coal and air at the same time. To examine this statement 
more fully it is necessary that we should know something of the 
chemical constituents of coal and air. 

Coal varies in quality and composition, but the greater part of it 
consists of carbon, the remainder being composed of gases and ash 
(see Fig. 1). 

Air consists of a mixture by weight of approximately 23% oxygen 
and 77% nitrogen, or when measured by volume, 21% oxygen and 
79% nitrogen. 

Combustion is the chemical combination which takes place 
between the constituents of fuel and oxygen when the fuel burns. 
The heat-producing constituents of coal are carbon and hydrogen, 
heat being produced when these elements combine with the oxygen 
from the air. Coal must be heated to a temperature slightly above 



ASH 10% 




OXYGEN 8% 

« — HYDROGEN S% 
-*— NITROGEN H% 

SULPHUR |% 

CARBON 75% 



Fig. I AVERAGE COAL CONSTITUENTS 



r 



24 



25 



800°F. before it commences to burn, but very much higher tempera- 
tures are necessary for it to burn efficiently. 

Carbon and hydrogen are chemical elements and each requires a 
definite quantity of oxygen to burn it completely so as to obtain 
the maximum heat value. In this connection it is necessary for the 
carbon to combine with sufficient oxygen to form a colourless gas 
known as carbon dioxide, and for the hydrogen to combine with 
oxygen to form water vapour (steam). 

If, however, the supply of air is insufficient, incomplete com- 
bustion results and another colourless gas called carbon monoxide 
is formed. In burning to carbon monoxide only about 30% of the 
heat is produced as there is when adequate air to burn the carbon 
completely to carbon dioxide is supplied. 

1 lb. of carbon completely burned to carbon dioxide produces 

14,550 British Thermal Heat Units (B.Th.U.s). 
1 lb. of carbon incompletely burned to carbon monoxide 
produces only 4,350 B.Th.U.s, that is, about 70% of the heat 
is wasted. 

Now we have already given particulars of the constituents of coal 
but it must be clearly understood that these elements do not exist 
separately in the fuel. The actual composition is extremely compli- 
cated, but it is sufficient if we consider it as consisting of two main 
parts :— 

fl) Volatile (gaseous) matter, that portion which is given off as a 
gas when the coal is heated, and 

(2) Fixed (solid) carbon, in the form of coke, which remains 
behind after the volatile matter has been given off. 

Volatile matter consists of numerous gaseous compounds of 
hydrogen and carbon known as hydro-carbons. These may be 
observed as yellowish smoke issuing from the chimney of a loco- 
motive in which steam is being raised from cold, or when too many 
shovelfuls of coal are put on at one firing. 

At high temperatures, in the neighbourhood of 2,500 5 F the 
hydro-carbons split up into carbon and hydrogen and are burned to 
form carbon dioxide and water vapour, provided sufficient air is 
present. If, however, there is a shortage of oxygen some of the 
hydro-carbons escape up the chimney unburnt in the form of 
black smoke. 

A normal Yorkshire steam coal contains about 33% by weight of 
volatile matter, and this contains practically all the hydrogen 
present in the fuel. This latter has a weight-for-weight heating value 
of approximately four times that of carbon. 

I lb. of hydrogen completely burned to water vapour gives off 
62,100 B.Th.U.s of heat. 



The sulphur content of coal is small and is of little consequence 
a s a heat-producer. It is, however, usually found in the coal as a 
compound of iron known as iron pyrites. The sulphur burns out, 
leaving the iron, which at high temperatures tends to cause the ash 
to become welded together forming clinker. 

Nitrogen in the coal is of no consequence. The nitrogen in the air 
required for combustion, however, plays a very important part in 
actual practice. A considerable volume of nitrogen has to pass 
through the firebox in the air required for combustion: 1 lb. of coal 
requires approximately 12 lb. of air for combustion of which 9 lb. 
are nitrogen. The nitrogen does not burn, but it does restrict the 
rate of combustion. Also, due to the fact that it has to be heated up 
by combusted gases in the firebox, it causes considerable loss of heat. 
The loss is due to the high temperature at which the gases leave the 
chimney, approximately 700'-75O°F., and the loss due to this is, at a 
minimum, 10%. 

What Happens in the Firebox 

Let us now consider what takes place when coal burns in a 
locomotive firebox. Air is supplied to the firebox in two ways, viz. : — 

fl) Primary air, through the firegrate, and 

(2) Secondary air supplied through the firehole. 

Assuming coal has just been fired on to an incandescent (white 
hot) firebed, the volatile gases commence to be given off at once 
from the newly added coal, and are quickly drawn out of the firebox 
and through the smoke-tubes, and unless sufficient air for complete 
combustion is made available they will pass out of the chimney-top 
in the form of dense smoke. Whilst the volatiles mix with a certain 
amount of primary air this will almost invariably be insufficient, and 
they will therefore depend upon adequate secondary air supply 
through the firehole door to enable proper combustion to take place. 

As has been stated previously, the volatiles contain a large propor- 
tion of the heat value of the coal, and any failure to provide adequate 
air for combustion of these will result in considerable heat loss. The 
fixed carbon, which remains after the volatiles have been driven off, 
remains on the firebed until sufficient primary air is provided through 
the firegrate to burn it, and here again sufficient secondary air must 
be provided to ensure that the carbon is fully burned to form 
carbon dioxide. 

Heat loss can also occur through admitting more air than is 
required for combustion: this excess air does not take part in 
combustion, and is heated up by the burning gases in the firebox, 
losses occurring due to the high temperature of discharge from the 



26 



TOO LITTLE 
AIR 



PER CENT. 
EXCESS AIR 

2 5 

SO 

7-5 

100 

12 5 

150 

17-5 

20 

22 S 

25 

27-5 



30 

TOO MUCH 32-s 
AIR 

35 

37-5 

40 



PER CENT. AVOIDABLE HEAT LOSS 
(NOT INCLUDING SMOKE) 

■ 11-4 



BLACK SMOKE 




LIGHT GREY SMOKE — 



NO SMOKE 




27 



Fig. 2 EXCESS AIR, HEAT LOSS AND SMOKE 



chimney in the same way as occurred with the nitrogen as described 
previously. 

As a matter of interest, it is necessary to supply about 20% more 
air than is theoretically necessary to complete combustion in a 
locomotive firebox. If only the theoretically correct amount of air 
is supplied it is not possible to fully mix this with the combustible 
gases due to the high speed at which they are drawn through the 
firebox to the tubeplate, and losses occur due to incomplete 
combustion in consequence (see Fig. 2). 

Principles of Good Firing 

From the foregoing we have seen what conditions are required 
for efficient combustion; it is now necessary to see how proper 
combustion can be attained in actual practice. 

On the road the art of firing is to regulate the fire and height of 
water in the boiler at all times according to the work to be performed 
and to have full boiler pressure when it is required, without 
blowing off. 

Different types of coal require different handling, dependent upon 
their constituents. For example, a good-quality Welsh steam coal is 
very largely composed of fixed carbon and contains a comparatively 
small amount of volatile matter. Such coal requires a greater 
amount of primary air and less secondary air through the firehole 



door. On the other hand, a good-quality Yorkshire steam coal is 
proportionately high in volatile matter and requires considerably 
more secondary air. 

Coal will be economically burnt when the firebed is of the right 
thickness. If the fire is too thick the air cannot pass through it. 
If the tire is too thin, excessive air passes through the firebed and holes 
will be formed. In both cases the firebox temperature will be 
considerably reduced. 

As already pointed out, the volatile matter begins to be expelled 
from the coal immediately it is placed on the firebed. If too much 
coal is fired at one time the amount of volatile matter given off will be 
so great that it will be impossible to provide enough air to burn it 
completely. The amount given off must therefore be controlled so 
that it is no greater than that which the air supply can burn com- 
pletely. This can be done by firing only a relatively small number of 
shovelfuls at one time. 

The whole of the volatile matter is not given off immediately the 
coal is fired and it is therefore necessary to wait before firing again 

FOR A PERIOD LONG ENOUGH TO ENSURE THAT THE AIR SUPPLY CAN 
THEN BURN THE VOLATILE GASES STILL BEING RELEASED FROM THE 
FIREBED TOGETHER WITH THE LARGER AMOUNT WHICH WILL BE GIVEN 
01 1 IMMEDIATELY THE NEW FIRING TAKES PLACE. 

Volatile matter requires an extremely high temperature for 
proper combustion, and one of the purposes of the brick arch is 
to maintain this high temperature. It increases the length of the 
path the gases must travel and causes them to be rapidly ignited. The 
brick arch receives heat from flames and radiation from the firebed 
itself and, therefore, the fire must be kept at the highest possible 
temperature. This can be done by working with a fire no thicker than 
the minimum needed to produce a uniform firebed without holes. To 
keep the firebed at this thickness the coal must be fired at the same 
rale as it is being burned away. 

To obtain the maximum amount of heat for the production of 
steam, the best method of firing is to limit the amount of coal put 
into the firebox at one time and to fire again only when the last 
charge of coal has burned away. 

Although steam locomotives appear to work harder up rising 
gradients they also travel more slowly and so use little (if any) more 
steam in a given period of time than when working more easily but 
travelling faster on easy gradients. This means that because the 
demand for steam remains fairly constant all the time the regulator 
is open, there is no need to increase the rate of firing to any great 
extent when climbing gradients. 

Fire sparingly — work systematically. This is the essence of good 



28 



firing and has been proved conclusively, not only by tests but bv 
analysing the way the best firemen work in practice cJthe oad No 
hard and fast rules can be laid down because locomotives vary at 
much as the work they perform and the men who man them 
However, for the larger locomotives the best results are found Tn 
uTd hvV° ^ 3ChiCVCd r by n0t CXCeedin « n sho « lf ^ at one time 

Smalkr lo JtZT™ T '**" '* "^"^ f ° r good combustion, 
bmal er locomot ves need proportionately less at a time but the 

actual rate of firing will be found by simple observation, for when 

too many shovels of coal are being persistently thrown mto the 

""ess^y Wi " r6SU,t and ' he thiCk "" S 0t the «^ ™ 

firing wh S! a h SSeS K° f ! OCOmo,ives ,he ™st »»on mistake is over- 
firing, whether by large amounts haphazardly fired or by small 

eTuTbu Th to r fle ?- Not only is valuab ' e coal *^ ™ 

«S , the , J ° b « a ' S0 made harder ,han " "«d be, because 
combustion is less efficient. m=».<iu»e 

Preparing the Fire 

First make sure that the water level in the boiler is correct and 
ha, every par , of the firebars is free from clinker and ash by'" nlng 

h! . h t" g th , em ,f necessar >' and knocking dust through "mo 
the ashpan. When the coal is of a clinker-forming nature Zee wo 
o three shovels of broken fire-brick or limestone onlhegra^e when 
a h ,s forming this will prevent clinker from running Tver tne 
firebars, restricting the air passage 8 e 

thS Th™ fi HH ''" Sta « es: ,P ut °" * ] W °f coal and let this bum 
through then add another layer, until the depth of the firebed k 
correc for the work in hand. This method ensures that the fire 
properly burnt through before starting. If steam is not immediate v 
required, regulate the dampers; this will prevent (I) the fire burnin. 
up too quickly (2) making smoke, and (3, blowing off * 

JtiS? 31 V aShpa " iS Ckan > the sm ° keb ox door « screwed 

th fi re™ if ZT^ bcf ° r = Star,in « ™V f ™ «ta shed, to examine 

Wpicferccfar Ml h : ?,ht^ l, are e ra P iV i ho P ,° SSibl 7 i, H h 
patches ,„ the fi r ebcd and that ^aJeTbZ,^^ o" fh 



29 



Starting Away with the Train 

On no account should the locomotive be fired when starting away. 
At this time the temperatures of the firebed and brick arch are much 
lower than they will be at any other stage of the journey. The object 
now is to raise their temperatures as quickly as possible. This can 
best be achieved by partly closing the firehole door; by this means 
the greater part of the air flow, called primary air, passes through the 
firebed and raises its temperature. The amount of volatiles being 
given off by the fire at this stage is small on account of the low 
temperature, and therefore a large quantity of air over the firebed, 
that is, through the firehole door, called secondary air, is not 
necessary if the fire has been prepared properly. If the coal is put 
on the fire before it has reached a high temperature, it merely cools 
the fire, delays good steaming and wastes coal (see Figs. 3, 4a and 
4b). After the train has travelled a little way and the driver has 
notched up the gear, that is the time to fire. The first shovelful 
should be placed where the fire is thinnest and if it is being pulled 
into holes, these should be filled up smartly; if there are patches 
which are not burning properly, miss them. Watch the chimney; 
if the fire is correct there will be in 15-20 seconds a light smoke at the 
chimney-top. When this light smoke has disappeared it will be time 
to fire again; the fire should be burning evenly all over the grate and 
the appropriate number of shovelfuls, according to the type of 
locomotive and work to be performed, should be added. 

Firing on the Journey 

After a few firings the fireman will prove for himself that the rate 
of firing need be no more than "little and often" and this also applies 
when the engine is climbing gradients. It is, of course, quite true 
that engines burn more coal per mile on rising gradients than when 
running on the level, but this docs not mean the fireman should fill 
the firebox with heavy charges of coal at one time. In such cases 
the number of shovelfuls fired should not exceed one or two, 
certainly no more than two, over the number used on the level. 
Good team work by enginemen has a bearing on maintaining a good 
head of steam; this co-operation between the Driver and Fireman is 
most important with regard to economy in the use of coal. 

An inefficient Fireman sometimes blames the Driver for using 
steam at an excessive rate; on the other hand, the Driver may 
charge the Fireman with mismanagement of the fire, allowing the 
boiler pressure to fall, and in order to keep scheduled time it is 
necessary for the Driver to increase the engine cut-off, thereby using 
more steam. If, therefore, the Fireman provides a satisfactory boiler 




31 



Fig. 3 CORRECT FIRE 

Firebed with even surface; no air holes, hollow places 
or dead patches: every square (oot of grate doing its 
job: combustion space above firebcd full of intensely 
hot flames: combustion completed in firebox 

Fig. 4a INCORRECT FIRE 

Firebed uneven; air unable to flow through thick 
patches under door and front of brick arch; too much 
air flowing through hollow patch and up to the sides 
of the firebox causing gaps in flames, combustion not 
completed in firebox; thick black smoke produced 

Fig. 4b INCORRECT FIRES 

Large lumps of coal cause dead spots in firebed. gaps 
m flame stream and uneven firebed surface 

Fig. S EFFECT OF SIZE OF COAL 

Fig 6 INCORRECT POSITION OF BAFFLE PLATE 




Fig. 4 



pressure, the Driver, by skilful handling of the gear, can carry out 
the work in hand without having to resort to the use of excessive 
rates of steam consumption. 

When the Regulator is Closed 

When the regulator is closed on the journey, or about to be closed, 
no firing should be done. Also, toward the end of a run, the rate of 
firing can be decreased or stopped completely at some point which is 
found by experience to avoid arriving on the shed with too great a 
quantity of fire in the box. 

When locomotives are standing in stations or sidings waiting to 
leave at an unexpected time the fire can be kept right by placing a 
few shovels of coal very occasionally, first at one part of the grate 
and then at another. In this way excessive smoke is prevented and the 
fire temperature can be raised quickly when required. 

Blowbacks 

When an engine is steaming normally a rate of burning is main- 
tained which is proportional to the rate of steaming. Coal is 
consumed on the grate, and the gases produced are burnt above the 
fire in the secondary air stream which is drawn through the firehole 
door by the action of the exhaust steam passing through the blast 
pipe. This air stream can also be maintained by the action of the 
blower and it draws the flames and also the products of combustion 
towards the smokebox. If this air stream is interrupted, e.g. by 
closing the regulator, without opening the blower sufficiently, the 
combustible gases which are still being produced will be trapped in 
the firebox with two possible results: — 

(a) Combustion may continue in the vicinity of the firehole door 
where air is still available. In these circumstances combustion 
will move towards this area, and flames will issue from the 
firehole door, producing what is known as a non-explosive 
blowback. 
(h) Combustion may cease momentarily, and the gases then re- 
ignited from the firebed; this would produce an explosive 
blowback with very rapid flame propagation and possibly more 
serious results, due to flames entering the cab. 

Contributory factors to blowbacks arc: — 

(a) Hard coals and some briquettes with their distinctive long 

flames. 
(/>) Black fires which produce more combustible gases than can be 

consumed. 



32 



(r) Running bunker or tender leading with the damper immediately 
below the firehole fully opened. Combustion in these circum- 
stances tends to be much more rapid in the vicinity of the air 
intake below the grate resulting in the emission of eases and the 
presence of flame in the vicinity of the open firehole door. 

id) Low tunnels and bridges may momentarily arrest the normal 
direction of the air-gas stream. 

0) A plate of the self-cleaning smokebox arrangement falling 
across the blast pipe due to insecure fixing. 

,nIvn,H 0ll ° W i n8 , POi r ntS u ShOUld ' ^^ be borne in m '' n d *" order 
to avoid incidents of this nature:— 

(1) Avoid black fires by overfiring, which besides wasting fuel 
produce excessive quantities of combustible gases. 

(2) Always open the blower before closing the regulator, and also 
when approaching low tunnels, deep cuttings or bridees 
especially when using hard coal or briquettes. 

(3) Avoid using the trailing damper when running bunker or 
tender leading. 

(4) During preparation ensure that the self-cleaning equipment in 
the smokebox is securely fixed. 

(5) When locomotives are working coupled together, and it is 
necessary to take water when passing over water troughs, the 
footp ate staff ,n charge of the locomotive in the rear must take 

he additional precaution of seeing that the blower is open and 
the damper and firehole doors are in the closed position. 

Firing of Shunting Locomotives 

tZ^ ^ / ^ ,ocom otives is intermittent in character so 
that the demands for steam are varied; nevertheless, the rules' of 
efficient firing still hold good. The general principle of 'Mi tie and 

tteU'n l b 7 PPlied by "*** few shove,fu ' s of coal at each 
■s workfng nng ^ ^ " PraCtiCab,y P ° SSible ° n, y Whi,st the e ^ne 

Size of Coal 

A large lump of coal, which when thrown on to the firebed 
protrudes above the general level, will burn more slowly than the 
rest of the bed and create a dead spot in the fire. Since maximum 
!h nM? ?\° nly bC aChieved With an even firebed, such lump™ 
H7'r, be t r °A en UP - S ° that they wi » burn ^ the same rate asX 
m n s f T " ^^ F,g ' * A 8 ° 0d S,Ze t0 aim at is abo " that of a 



33 



Use of Fire-irons 

Firemen should avoid the use of fire-irons as far as possible. If the 
fire is caked, the fire-irons should only be used to break up the 
surface. If there is a good depth of fire when the ash and clinker are 
lifted up and mixed with the incandescent fuel, the ash will melt and 
run into the spaces between the firebars making things worse. If 
clinker has formed and it is necessary to break it up whilst running, 
the fire should be run down as low as possible and the clinker will 
then be much easier to break. 

Use of Baffle Plate 

The baffle plate placed in the firehole is designed to direct the 
air down towards the firebed in order to mix it thoroughly with the 
hot gases and flames. 

If this plate is not in place, tilted upwards or burnt too short, cold 
air can pass over the nose of the brick arch to the upper section of 
the tubeplate, setting up considerable strains in these parts of the 
firebox, causing leaking tubes, dirty tubcplates and giving poor 
combustion (see Fig. 6). 

Use of Dampers 

The dampers control the flow of air through the ashpan to the 
firebed and they can be used to good effect to control the rate of 
burning under all conditions when the regulator is closed. 

There can be no hard and fast rule as to which dampers should be 
used when the regulator is open on the journey; this depends upon 
the judgment of the Fireman. 

Working of Injector 

Both injectors should be tried before leaving the shed with the 
boiler pressure close to its maximum to ensure that they are in good 
working order, so saving anxiety on the run. When starting away 
with a train the water level in the boiler should be in sight at the top of 
the gauge glass. The injector can then be left olf until the Fireman 
has fired a few times and the firebed and brick arch temperatures 
have been raised. When the water level drops to about J in. from the 
top, the injector can be put on; the steam valve should be well open 
and the feed-water regulator pulled round towards the minimum, 
in order to ensure that the water enters the boiler at the highest 
possible temperature. The Fireman will then be doing all he can to 
keep up a constant feed to the boiler. The quantity of water put 
into the boiler should be equivalent to the amount of steam used by 
the engine. The injector feed should be adjusted to obtain these 
conditions. 



34 



35 



SECTION 3 

TRANSFORMATION OF 
HEAT INTO POWER 

The steam locomotive is a power plant in which there are four 
distinct divisions: — 

(1) Fuel and combustion. 

(2) Steam. 

(3) Utilisation of steam. 

(4) The driving mechanism. 

Heat is a form of energy; therefore, when coal burns in the firebox 
of a locomotive its heat energy is capable of being expressed in 
terms of useful work. The high temperatures attained in the firebox 
by the combustion of the fuel varies according to conditions and 
may reach a maximum of 3,000 e F. The heat so generated is trans- 
ferred to the water in the boiler through the firebox plates and tubes 
where it is converted to pressure energy in the form of steam, the 
steam in turn being led to the cylinders where it is transformed into 
mechanical energy and through the medium of the driving 
mechanism results in the tractive power of the locomotive. 

British Thermal Unit 

The production and utilisation of heat are the Fireman's chief 
concern ; water and steam are only a means to an end— they bear the 
same relationship to a locomotive as does the harness to a horse that 
pulls the load. The state of the amount of heat or "hotness" in the 
firebox is measured by its temperature, and the unit of heat in this 
country known as the British Thermal Unit (B.Th.U.), is 1 180th 
part of the heat required to raise the temperature of 1 lb. of water 
from freezing point to boiling point, i.e. 32° to 212°F., this being 
usually taken as the heat required to raise 1 lb. of water' I °F. 

Methods of Heat Transfer 

There are three methods by which heat may be conveyed from one 
body or place to another:— 

Conduction: 

Heat passes from one body to another by contact, warmer 
part.cles impart heat to the colder bodies. For example boiler 
tubes transmit heat from the hot gases to the water through 
the metal by conduction. 






Convection: 
This is the transfer of heat by the hot gases in the firebox and 
by the circulating currents set up in the water, which takes the 
heat from the high-temperature parts. The moving hot gases in 
the firebox and circulating water in the boiler carry heat by 
convection to or from the metal surfaces with which they come 
in contact. 

Radiation: 
The fire in the firebox gives off energy in the form of radiant 
heat. Heat thus radiated to a body may be reflected, absorbed 
or transmitted. In the case of the firebox crown sheet the heat 
is absorbed by the metal, little being reflected, and the heat is 
then transmitted by conduction through the metal to the water. 

Relation of Temperature to Pressures 

When heat is applied to water to raise it to boiling temperature 
(212°F.). any additional heat will result in the water being trans- 
formed into steam at atmospheric pressure (14-7 lb. per sq. in.). 
Steam generated in a boiler, being enclosed, cannot escape, and if 
the application of heat is continued, more and more water is con- 
verted into steam which, being elastic, becomes compressed, 
decreases in volume and increases in pressure. As the pressure of 
steam on the surface of the water increases, so the temperature at 
which the water turns into steam rises correspondingly. 

At atmospheric pressure (0 lb. per sq. in. on pressure gauge) 
1 cu. in. of water when converted into steam occupies 1,642 cu. in. 
or nearly 1 cu. ft. At 15 lb. per sq. in. on the pressure gauge this 
steam will occupy only 821 cu. in., the pressure being doubled and the 
volume reduced by half. At 30 lb. per sq. in. the volume is only 
410 cu. in., the steam being now compressed to one-fourth of its 
original volume. At 2501b. per sq. in. the volume of 1 cu. in. of 
water converted into steam is only 1 10 cu. in. 

Saturated Steam 

The steam collected above the water in the boiler, termed 
"saturated steam", exerts an increasing pressure on its surface which 
resists the formation of the rising steam bubbles and calls for 
additional heat energy in the water. In short, the higher the pressure 
the greater the amount of heat required to create steam; for 
example: — 

Steam at atmospheric pressure has a temperature of 212°F. 

Steam at 85 lb. gauge pressure has a temperature of 327°F. 

Steam at 225 lb. gauge pressure has a temperature of 397° F. 

Steam at 250 lb. gauge pressure has a temperature of 405°F. 



36 



A table showing the range of steam pressure and temperature is 
given below: — 



STEAM PRESSURE-TEMPERATURE 


TABLE 


Gauge Pressure 


Temperature 


Gauge Pressure 


Temperature 






lb. per sq. in. 


F. 





2120 


170 


375-2 


50 


297-9 


175 


377-4 


100 


337-8 


180 


379-6 


120 


3500 


185 


381-7 


130 


355-5 


190 


383-8 


140 


3608 


195 


385-9 


150 


365-8 


200 


387-9 


160 


370-6 


220 


395-6 


165 


372-9 


250 


406-3 



Superheating 

Should the steam be further heated while in contact with the water 
from which it was generated, more water will be evaporated and the 
quantity of steam increased with an increase of temperature and 
pressure until the action of the safety valves prevents any further 
increase. On the other hand, if heat be added to the steam apart 
from the water from which it was generated, the steam becomes 
superheated and its temperature rises above that due to its pressure. 
The superheating of the steam is generally performed while the steam 
is no its passage from the regulator valve to the steam chest. 

The temperature of superheated steam at working pressure ranges 
from about 600°F. to 750°F. depending upon the design of the 
superheater and the way in which the locomotive is being worked; 
in other words, the steam is heated about 300 5 F. above the saturated 
steam. The three main advantages of superheating the steam are 
that any entrained water in the saturated steam is converted into 
additional steam, cylinder condensation is prevented and the volume 
is increased as compared with saturated steam. This increase in 
volume is approximately 30% at a working pressure of 225 lb. per 
sq. in.: in consequence of this increase the demand upon the boiler 
to supply steam to the locomotive cylinders is considerably reduced, 
resulting in a saving in water and fuel. 

The arrangements of the superheater and the utilisation of the 
expansive properties of the steam are described in subsequent 
sections. 



37 



SECTION 4 

THE BOILER: 
BOILER MOUNTINGS AND DETAILS 

Types of Boilers and Fireboxes 

The boiler or steam generator consists essentially of the steel shell, 
which includes the boiler barrel, the outer firebox wrapper plate, 
back plate, throat plate and smokebox tubeplate, also the inner 
firebox and the steel flue tubes. Fig. 7 shows a design of a boiler 
supplying saturated steam and Fig. 8 a boiler for supplying super- 
heated steam. The latter figure illustrates a taper boiler, the 
cylindrical barrel is made in two sections with the larger diameter at 
the rear, where the barrel is joined to the outer firebox. The dome in 
this design, which houses the regulator valve and auxiliary internal 
steam pipes, is positioned on top of the rear sloping section of the 
boiler barrel, where it forms a collector for steam above the surface 
of the water. 

Fireboxes may be of the deep, long, narrow type between the 
frames or of the shallow, wide type, for example, as fitted to 4-6-2 
classes of locomotives. In the latter case the firebox is spread over 
the frames. The wider type of firebox is generally employed when a 
large grate area is necessary. 

The inner firebox is supported from the outer firebox by the 
foundation ring at the bottom, by crown stays at the top, and by 
palm stays between the firebox tubeplate and the boiler barrel. In 
addition, the firebox and outer wrapper plates, back plate and throat 
plate are stayed together with steel or copper stays, at about 4-in. 
pitch; there are over 1,000 of these stays in every locomotive boiler. 
Longitudinal stays are also fitted between the boiler back plate and 
smokebox tubeplate, and cross stays between the sides of the outer 
wrapper plate above the firebox crown. From the firebox tubeplate, 
the steel flue tubes, which may be anything from H in. to 2 J in. 
diameter, pass through the boiler barrel to the smokebox tubeplate. 
When the boiler is fitted with a superheater, a number of large flue 
tubes (approximately 5 in. diameter) are provided in which super- 
heater elements are positioned. 

Some boilers employ the flat-top type of firebox. 

The boiler barrel and firebox are lagged with asbestos or glass 
wool. 

It is normal practice in this country for inner fireboxes to be made 



38 



UJ 

-J 

6 

CO 

UL 

o 

UJ 

> 
-J 

< 

Z 


u 



M 



Fig. 7 




39 




go./, <£<o 



as su as 



ill 



55 I 



OUfg 

Ill US a,*** 

< Z > > < 3 « 2: * -i 






oca: 

oo< 



si!* 

-<ff Zo 



ill 
§lg§ 

Kci2 



I 

I 

UJ 

D 

(A 

X 

I- 



LU 

-J 



CD 
u_ 

o 

UJ 

> 
< 

z 
o 

U 

UJ 



DO 



Fig. 8 



40 



of copper. The 4-6-2 type locomotives of the Southern Region 
(Merchant Navy and West Country classes) are, however, fitted with 
steel fireboxes and also with thermic syphons which increase the 
firebox evaporative surface and improve circulation in the boiler 
(see Fig. 9). 

The Smokebox 

The smokebox is an extension at the front end of the boiler barrel 
which, together with the blast pipe and chimney, forms the means of 
inducing air required for combustion to the firebox. Apart from the 
chimney orifice it is airtight. Other fittings in the smokebox are: 
superheater header (when fitted), main steam pipes, blower and 
ejector exhaust pipes. On some locomotives the regulator valve is 
situated in the superheater header in the smokebox (see Fig. 10). 

Self-cleaning Smokebox 

To avoid the accumulation of ashes in the smokebox, to even the 
effect of the blast over the whole tubeplate and to prevent emission 
of sparks thrown up the chimney, locomotives are now being fitted 
with self-cleaning type of smokebox (see Fig. 1 1). Deflecting and 
diaphragm plates with front spark arrester or ash plate are fitted. 
The vertical diaphragm plates, in front of the tubeplate, ensure that 
an equal draught passes through the tubes. The self-cleaning action 
is attained by locating the horizontal table plate just under the top 
flange of the blast pipe and setting the restriction plate at such an 
angle as, combined with sufficient area of netting, will allow for the 
free steaming of the locomotive. The diaphragm plates cause the 
ashes, drawn through the tubes, to traverse the lower part of the 
smokebox through the restricted opening "A" (Fig. 11); the ashes 
are then drawn through the wire net screen before being ejected 
through the chimney. By that time the ashes are small, dead and 
harmless. 

The Superheater 

The superheater consists of a steam collector or header for distri- 
buting steam from the boiler to a series of superheating tubes or 
elements and for receiving the superheated steam from the elements. 
The superheater header is attached by a flanged joint to the smokebox 
tubeplate at the outlet of the main internal steam pipe from the 
regulator valve and is placed horizontally across the upper part of 
the smokebox. At each side of the header are flanges to which are 
attached the main steam pipes to the cylinders (Fig. 9). 

The header casting is divided into saturated and superheated 
compartments. Steam passing from the regulator valve to the main 






41 







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a. 
>- 

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ec 

Ui 

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H 

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H 



LU 
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eo 







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LU 

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Fig. 9 



42 







43 



IgillplillSili 

iPlliliSiMSii 



Fig. 10 



MESH SCREEN 



A. RESTRICTION CAUSED BY 
DEFLECTOR PLATES FOR 
LIFTING ASH 

DIAPHRAGM PLATES 



SUPPORTING 
BARS 




TABLE 
PLATES 



TUBE PLATES 



DEFLECTOR PLATES 
SUPPORTING BARS 



DIAPHRAGM PLATES 



Fig. II TYPICAL SELF-CLEANING SMOKEBOX 



internal steam pipe can only reach the cylinders by traversing the 
superheater elements connecting the two compartments in the 
header, the elements forming the only communication between the 
two separate sections. On modern locomotives the number of 
superheater elements installed varies according to the size of 
the boiler and the degree of superheat required. The elements 
usually consist of continuous steel tubing of four lengths with three 
return bends, or of the bifurcated type with two return bends: the 
elements are positioned in large flue tubes which extend between the 
firebox and the smokebox tubeplates above the ordinary boiler 
tubes. Superheater flue tubes are from 5 in. to 5 J in. diameter, 
reduced at one end for a distance of about 8 in. from the firebox 
tubeplate. The standard superheater element measures approximately 
\'i in. outside diameter and extends from the header in the smokebox 
to within a short distance of the firebox tubeplate, sufficient to avoid 
the element return bends coming in direct contact with the flames 
from the firebox. 



44 



The steam is superheated by the firebox gases flowing through the 
large flue tubes, giving up part of their heat to the steam passing 
through the elements when the regulator is open. The steam is first 
dried and then superheated. For example, steam at a pressure of 
225 lb. per sq. in. and at a temperature of 397°F. enters the super- 
heater header in a saturated state and, traversing the elements 
returns to the header at a temperature of about 600°F., having been 
superheated by just over 200°F. and increased in volume by 
approximately 35%. J 

Blast Pipe 

It has been stated in the section dealing with combustion that a 
arge amount of air is necessary for efficient combustion in a 
locomotive firebox. 

To supply the air, use is made of the exhaust steam from the 
cylinders in the following manner:— 

Exhaust steam, after leaving the cylinders, passes through the 
exhaust passages to the blast pipe cap where it is slightly throttled so 
as to form a jet. The cap and the chimney are fixed on the same 
centre line and are suitably proportioned in relation to oneanother 
so that the escaping jet of exhaust steam, when passing through the 
chimney, carries with it the waste gases, thus creating a partial 
vacuum in the smokebox which induces the firebox gases to pass 
through the flue tubes and which, in turn, induces air to pass into 
the firebox through the grate and firehole door. 

If the smokebox door is not airtight the vacuum will be reduced 
and bad steaming will result. 

Whilst the majority of locomotives have a blast pipe cap of the 
fixed cone type as described above, there are several variations. 
On ex-G.W.R. locomotives fitted with superheaters the "jumper"- 
type blast pipe cap is in extensive use. 

It consists of a blast pipe cap fitted with a "jumper" ring and 
when the locomotive is working heavily the exhaust steam pressure 
lifts the jumper ring and provides an additional outlet for the exhaust 
thereby reducing the tendency to lift the fire (see Fig. 12). 

For this type of cap to fulfil its purpose it is most important that 
it should be kept clean and in good working order and the Fireman 
should brush away any accumulation around the top each day when 
he examines the smokebox. If the top is found defective it must be 
reported. 

The double blast pipe cap comprises two fixed cone exhaust caps 
and requires two chimneys. The advantage of this design is that the 




45 



BLAST PIPE CAP 



JUMPER RING 



STOP 





JUMPER CLOSED JUMPER FULLY OPEN 

Fig. 12 JUMPER BLAST PIPE TOP 

same amount of draught can be induced with less exhaust pressure 

(see Fig. 13). „.. 

Many ex-S.R. express passenger locomotives are fitted with a 
multi-jet blast pipe cap which consists of five exhaust nozzles which 




Fig. 13 ARRANGEMENT OF DOUBLE BLAST PIPE 



46 






exhaust through one large-diameter chimney (see Fig. 9); this has 
the same advantages as the double blast pipe. 

Brick Arch 

The brick arch is constructed within the firebox, abutting on the 
firebox on each side (Figs. 7 and 8). It extends from the tubeplate 
just clear of the bottom row of tubes and is inclined upward 
Projecting into the firebox is the firehole door baffle or deflector 
plate, positioned so as to incline towards the arch from the firehole 
in a line slightly below the underside of the arch. 

Firehole Doors 

Various patterns of firehole door are fitted to locomotives- 
these give access for firing and also can be adjusted to control the 
ingress of secondary air. 

Drop Grates and Rocking Grates— Hopper Ashpan 

Drop grates are fitted to facilitate disposal of the fire. 

They are of varying types. One type consists of cast iron approxi- 
mately 2 ft. x 1 ft 3 in., which forms part of the firegrate but which 
being hinged, can be lowered to enable the clinker to be pushed 
through into the ashpan. On another type the drop grate forms the 
whole front section of the firegrate, as on some ex-L N E R 
locomotives. 

Rocking grates are being fitted to B.R. standard types of loco- 
motives These consist of hinged firebars which can be rocked by 
means of levers in the cab (see Fig. 14). 

A two-way stop and locking plate enables the grates to be operated 
with a limited amount of movement so as to break up the clinker 
when running, or to be rocked fully to enable the fire to be dropped 
at disposal. Care must be taken to see that the locking plate is in 
position during normal working. 

With this type of grate a hopper ashpan is provided (see Fig 15) 
This is fitted with bottom doors and is self-emptying when these are 
opened. The doors are held in position by a catch, and care should be 
taken to see that this and the locking key are secure after the doors 
have been closed tightly. 

The hopper doors should always be opened prior to dropping the 
pre durmg disposal to prevent the hot fire damaging the ashpan 
and these operations should only be carried out over a pit or other 
authorised cleaning point. 




47 



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2 

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Fig. 14 



48 



49 






HANDLE IN CLOSED POSITION 
HANDLE IN OPEN POSITION 




FRONT HOPPER DOOR 



MIDDLE HOPPER DOOR 



BACK HOPPER DOOR 



Locking catch, lifted to this position 
■ to disengage locking arm 




OPERATING ARM AND 
HANDLE SOCKET 



Fig. IS ARRANGEMENT OF HOPPER ASHPAN 

Boiler Mountings and Steam-using Auxiliaries 

The boiler mountings and steam-using auxiliaries necessary for 
the efficient and safe working of locomotives are as follows-— 

1 . Safety valves. 

2. Water gauges. 

3. Pressure gauge. 

4. Fusible plugs. 

5. Injectors and clacks. 

6. Regulator valve. 

7. Washout plugs, hand hole and mudhole covers. 

8. Blower valve and ring. 

Safety Valves 

Safety valves are fitted to prevent the boiler pressure from 
exceeding the registered working pressure of the boiler which is the 
steam pressure for which it was designed and is indicated by a metal 
tablet secured to the firebox back plate. 

If the pressure at which the safety valves commence to blow off 
differs more than 5 lb. per sq. in. from the registered boiler pressure, 



this fact must be reported on a "Repair" card. 
The "Pop"-type safety valve is in extensive use on Butish Railways 

(see Fig. 16). 



CASING 




BOTTOM 
SPRING CAP 



VALVE 
VALVE GUIDE 



Fig. 16 SAFETY VALVE 

In this design, when the working pressure is reached, the spring- 
loaded valve rises and admits small amounts of steam through a 
lip on the valve to the annular chamber, and this escapes through 
the holes in the top cap of the valve. 

The steam, when escaping, acts on the increased area of the top 
cap and adds to the force already keeping the valve off its seating 
until such time as the pressure in the boiler has dropped slightly. 
The spring then overcomes the pressure of the escaping steam and the 
valve is instantaneously closed. 

Blowing off can be avoided by careful management of the nre and 
injectors. On a modern 4-6-0 locomotive with a tractive effort in the 
neighbourhood of 26,000 lb. there is a loss of pressure and wastage 
of approximately 10 gallons of water for each minute the safety 
valves are open. 

Water Gauges 

Water gauges are mounted on the boiler back plate in the cab of 
the locomotive and are positioned so that when the water is in sight 






50 



Fig. 17 WATER GAUGE 




GAUGE GLASS 



GAUGE GLASS 
PROTECTOR 



BOTTOM 
WATER COCK 



TO TEST GAUGE COCKS 

1. Shut cop cock and bottom cock by pulling handles A and B backwards until horizontal 

2. Open dram cock by pulling handle C backwards until horizontal and water should disappear 

3. Blow through top cock by opening with handle A and close agam 

4. Blow through bottom cock by opening with handle B and close again 

5. Shut drain cock with handle C 

«. Open top cock and bottom cock with handles A and B and water should rise to level 



51 



TO TEST GAUGE COCKS 

1 Shut top and bottom cocks by pulling 
handle A until it is pointing downwards 
halfway between the horizontal and 
vertical 
1 Open drain cock by pulling handle B up- 
wards until horizontal, and water should 
disappear 
3 Open top and bottom cocks by raising 
' handle A slowly until it is pointing upwards 
halfway between the horizontal and 
vertical in order to'blow through, and close 
again 
4. Shut drain cock by turning handle B down- 
wards 
5 Open top and bottom cocks with handle A 
until it is pointing upwards halfway be- 
tween the horizontal and vertical and 
water should rise to level 



WATER LEVEL 



"A" 



|J FRONT PLATE \\ 

S INNER p B L A A C t K e"A\ 

\ 



LINER. 
PLATE 




OPERATING 
HANDLE STOP 

TOP COCK 

RESTRICTOR 

VALVE 
TOP COCK 

BODY 
RUBBER WASHER 

GLAND NUT 

DOUBLE FLANGED 
PILLAR 

GAUGE GLASS 

CONNECTING 
LEVER 

BOTTOM COCK 

BALL VALVE 

BOTTOM COCK 
BODY 

DRAIN COCK 



Fig. 18 WATER GAUGE 
TOP AND BOTTOM COCKS COUPLED 



at the bottom of the glass, the firebox crown is covered. 

When working under normal conditions the water should be kept 
in sight in the top half of the glass, and before descending severe 
gradients or working over curves with a large amount of super- 
elevation a higher water level should be carried. 

Normal running with too high a water level is detrimental to 
efficient locomotive performance in that a larger amount of water is 
carried over with the steam and the risk of priming is increased. 

Types of water gauges are shown in Figs. 17, 18 and 19. 



52 




/ ■£ HANDLE "A" 
' "ON" POSITION 



VALVE 

RUBBER 
PACKING RING 
^— GLAND RING 

GLAND S.N, 
NUT f\J 

HANDLE "A" 
"OFF" POSITION 

'GLAND NUT 
.GLAND RING 

RUBBER 
PACKING RING 

-PLUG 

*BALL VALVE 

; UNION AND NUT 

• BLOW-THROUGH 
COCK 



Fig. 19 WATER GAUGE WITH TEST COCKS 



Pressure Gauge 

The essential element of the pressure gauge is the Bourdon tube, 
connected by mechanism to a finger which indicates the pressure of 
steam in the boiler. The tube, usually made of phosphor bronze, is 
of oval cross-section and bent in the form of an arc of a circle, 
having one end fixed to a block which has a screw connection to the 
steam gauge pipe. The other end of the tube is sealed and is con- 
nected by a rod and pinion which magnifies the movement. 

When pressure is applied, the tube tends to straighten out and the 
free end lifts by an amount proportional to the pressure applied bv 
the steam. 

Similarly, if a vacuum or negative pressure is applied the tube 
tends to close up and the pointer moves in the reverse direction as 
in a vacuum gauge. 

Fusible Plugs 

One or more fusible plugs are screwed into the firebox crown. 
These are of brass; some have a lead core which melts at a com- 



53 






paratively low temperature, and others have a brass button, secured 
by a lead filling. 

If the water level in the boiler drops too low and uncovers the 
plugs, the lead melts and allows steam to escape into the firebox, 
which acts as a warning to the Enginemen. Should this occur both 
injectors should be immediately put on and steps taken to remove 
or deaden the fire. 

Washout Plugs, Handhole and Mudhole Doors 

These are fitted to facilitate periodical inspection and cleaning of 
the boiler water spaces. 

Blower and Valve 

The blower consists of a perforated ring fitted round the top of the 
blast pipe cap or, alternatively, cast integral with the base of the 
chimney, the steam supply being controlled from a valve on the 
footplate. 

Its function is to create a smokebox vacuum for the following 

purposes : — 

(a) To increase the draught on the fire when the locomotive is 
stationary in order to raise steam pressure. 

(b) To clear smoke. 

(c) To counteract back draught. 

\d) To supplement the blast, if necessary. 

In the case of (c), whilst working a train or light engine, the blower 
valve must always be opened prior to closing the regulator, also 
before entering a tunnel, and when passing over water troughs 
should be used as a further precaution to closing the ashpan dampers 
and firehole door. 

Regulator Valves 

Regulator valves of the vertical slide, horizontal slide balanced 
circular and double-beat types as well as the multiple-valve type in 
the superheater header are in common use on British Railways. 

Vertical Slide-type Regulator 

A typical vertical slide type is positioned in the dome as shown in 
Fig. 20. The regulator head usually has four ports, two small for 
starting purposes and two large size for normal running. The main 
valve, which has four ports, slides on its seating on the regulator 
head, and the pilot valve in turn seats upon the main valve, being 
held in position by a flat spring. 

The first movement of the regulator handle lifts the pilot valve 
until the small ports are open. Further movement of the handle 



54 



s"\ 



CfSZi 



STARTING VALVE ^^ ^ RETAINING 




m^- 



Note: Retaining 

spring removed 

In this view 



REGULATOR ROD 
BOTTOM CASTING 



Fig. 20 REGULATOR VALVE VERTICAL DOME TYPE 

moves both the pilot valve and the main valve together, which 
action opens the large ports and closes the starting ports. During 
closing, the pilot valve is first moved over the main valve to its 
normal closed position and then both valves are brought back 
together to their original position, closing the steam ports as they 
come down. 

The independent movement of the pilot valve is obtained by the 
use of an elongated hole or slot in the main valve, the result being 
that the latter does not move until the pin has travelled a distance 
corresponding to the. clearance of the slotted hole, a distance which 
is equal to the lap and port opening of the valve. 

The pilot valve is provided to allow a gradual admission of steam 
into the main steam pipe so as to balance the pressure on the main 
valve, thus making easy and accurate adjustment possible. 

Horizontal Dome-type Regulator 

The horizontal slide dome type of regulator is shown in Fig. 21. 

It is similar in principle to the vertical pattern. 

A main valve and pilot valve are employed, but the operating pin 
engages with slots formed in the raised sides of the valves. The slots 
in the main valve are wider than the diameter of the pin by an 
amount equal to the lap plus the port opening of the pilot valve. 

Horizontal Regulator Smokebox Type 

This regulator employs main and pilot valves similar to those of 
the dome type, but is positioned in the smokebox (see Fig. 10). 



55 



STARTING VALVE 



MAIN VALVE 



RETAINING PLATE 







REGULATOR ROD 



Fig. 21 REGULATOR VALVE HORIZONTAL DOME TYPE 



Double-beat Type Regulator 

The double-beat type of regulator valve is shown in Fig. 22. 

This valve is mounted on a vertical cast-iron pipe in the dome. 
The valve is double, there being really two valves cast in one with 
two corresponding seats in the regulator head. 







EZXHZQ! 



Fig. 22 DOUBLE-BEAT-TYPE REGULATOR VALVE 



56 



Steam is admitted past both top and bottom seatings simul- 
taneously when the valve is opened, entering the lower seat by 
passing through the centre of the valve. In some designs the upper 
seat is somewhat larger than the lower seat to allow it to be placed 
in the head and, this slight difference in area between the top and 
bottom seats has the advantage of ensuring that the valve will 
move into the closed position should any connection break. 

Multiple Valve Regulator 

In this type of regulator a number of valves situated in the super- 
heater header open in turn as the regulator handle is moved; the 
object is to obtain fine regulation of the steam flow with a minimum 
of effort to operate the regulator. 

Injectors 

The injector is an appliance for delivering feed water to a boiler. 
In its simplest form it embodies three essential cones, the "steam 
cone", the "combining cone" and the "delivery cone". The steam 
cone admits the steam to the injector, guides it in the direction in 
which it should flow, and limits, by its bore, the amount of steam 
passing through. Steam leaving this cone comes in contact with the 
water, is condensed by it and passes into the combining cone 
(Fig. 23). 

STEAM CONE COMBINING CONE DELIVERY CONE 

T 

DELIVERY 




OVERFLOW 



WATER INLET 

Fig. 23 SIMPLE INJECTOR 



When steam is allowed to expand in the steam cone from a higher 
to a lower pressure a certain amount of heat is available for con- 
version into work and this is spent in giving velocity to the steam 
itself in the direction of its flow. 

The first point to remember, therefore, is that the change from 



57 



pressure energy to velocity energy is brought about in the steam cone. 

In the second or combining cone the slowly moving water com- 
bines with the swiftly moving steam, and the function of this cone 
is to ensure that the steam jet is condensed by the water. The cooler 
the feed water the better is the condensation of the steam. The 
combining cone is convergent in shape, the bore of the cone 
decreasing, with the result that the jet consists at its inlet end of a 
mixture of steam and water and at the outlet end of a solid jet of hot 
water flowing with high velocity into the delivery cone. Between the 
combining and the delivery cone is a gap, known as the overflow 
gap, through which excess steam and water are by-passed during 
the starting operation. 

The second point to remember is that the combining cone effects 
the complete combination of the steam and water into the solid jet 
by the condensation of the steam and the transference of its energy 

to the water. 

The delivery cone is so constructed that the change from velocity 
io pressure energy takes place as uniformly as possible. The 
momentum of the jet, which is greatest at the choke or smallest 
diameter of the delivery cone, is gradually reduced in velocity and 
increased in pressure sufficient to overcome the boiler pressure on 
the top of the clack valve. The temperature of the water is usually 
increased about 100°F. in passing through the injector. The size of 
an injector is determined by the throat or smallest diameter of the 
delivery cone, this dimension being stated in millimetres (mm.). 

The third point to remember, therefore, is that the function of 
the delivery cone is to convert the velocity energy of the combined 
jet into pressure energy. 

The early injectors described proved difficult to start and unreliable 
when used on locomotives, due to vibration, set up whilst running, 
affecting the combined jet of water and steam in its passage from 
the combining cone to the delivery cone. Modern injectors are 
designed to overcome this difficulty and automatically restart should 
they inadvertently "knock off". 

Fig. 24 shows a design of an injector which has been adopted as 
standard for British Railways. 

The injector works in exactly the same manner as described 
previously, i.e. a jet of steam emerging at high velocity from the 
steam cone is brought into contact with the cold feed water which 
surrounds the tip of the steam cone and is partially condensed, 
causing a partial vacuum. This in turn causes the water to be drawn 
forward at a considerable speed into the combining cone. Passage 
through this completes the condensation of the steam and at the 
same time it releases its velocity energy to the water which is forced 



58 



INJECTOR BODY 
STEAM CONE 




59 



DELIVERY CONE 

INSPECTION CAP NUT 

OVERFLOW VALVE SPRING 

OVERFLOW VALVE 

HOLDING 

DOWN BAR 



WATER 
INLET 






Fig. 24 INJECTOR COMBINING CONE 
WITH HINGED FLAP 

forward at considerable speed through the small end of the cone. 
The water jet then jumps the overflow gap and enters a diverging 
delivery cone where the speed of flow and velocity energy, on its 
passage through the cone, exceeds the boiler pressure sufficiently to 
enable the feed water to lift the clack valve and enter the boiler. 
The upper portion of the combining cone is formed by a hinged flap, 
and the vacuum developed in the combining cone, when the injector 
is working, holds this flap against the fixed portion which then 
forms a continuous cone. If the action of the injector is interrupted 
or the water jet upset, the vacuum in this cone is replaced by a 
pressure which forces the hinged flap open, allowing any surplus 
steam and water to escape through the gap so formed to the overflow 
outlet. When the pressure has thus been relieved the working vacuum 
rapidly re-establishes itself and the injector will then start again. 

Fig. 25 shows a type of injector which is fitted to large numbers of 
locomotives; in this arrangement the combining cone has a fixed 
and movable portion. In this arrangement the steam, during its 
passage along with the feed water through the combining cone, is 
fully condensed, causing a high vacuum which holds the movable 
portion of the cone in contact with the fixed portion, forming in 
effect one continuous cone; if, however, the action of the injector is 
interrupted or the water jet upset, the vacuum in the cone is replaced 



WATER PLUG 




STEAM INLET 

STEAM CONE 



OVERFLOW 
CONNECTION 



DRAIN COCK 



Fig. 25 INJECTOR COMBINING CONE 
FITTED WITH MOVABLE PORTION 



60 



Fig. 26 LIVE STEAM INJECTOR MONITOR TYPE 



UNIVERSAL JOINT 
STEAM 



STEAM NOZZLE 
INNER 




STEAM NOZZLE 
OUTER 



OVERFLOW VALVE 
HINGED 



BACK-PRESSURE VALVE 



OVERFLOW 



WORKING INSTRUCTIONS 
To Start: Open water valve, then steam valve fully 
To Shut Off: Close steam valve, then water valve 
Regulate for quantity with water valve 



by pressure causing the movable cone to leave its seating, thus 
allowing any surplus water and steam to escape through the overflow. 

When the pressure has been relieved the working vacuum is 
quickly re-established and the injector will re-start, the movable 
portion of the combining cone having again taken up its normal 
working position. 

One of the latest types of injectors is the "Monitor" type, as 
shown in Fig. 26 ; in this arrangement it will be noted that there 
are two steam cones and that the combining cone is without moving 






61 









parts, but is fitted with slots. When the water cock is opened, the 
water flows into the combining cone and passes through the slots to 
the overflow; when steam is turned on it is directed in two jets, first 
the primary annular jet, and second, the secondary forcing jet. The 
primary jet, on leaving the steam cone, comes into contact with the 
feed water and forces it down the combining cone past the end of the 
inner steam cone at which point the second jet of steam is introduced, 
giving further impulse to the combined jet. 

The combined jet flows through the combining cone where 
condensation is completed and then enters the delivery cone. 

Should interruption take place causing the injector to "knock off", 
the steam and water escape freely through the combining cone slots 
to the overflow until the jet is reformed by the condensation of the 
steam and the injector restarts. 

Exhaust Injectors 

Exhaust injectors provide an economical method of injecting 
water into the boiler by utilising a small amount of exhaust steam 
from the cylinder for this purpose. Exhaust steam which would 
otherwise go to waste also heats the feed water, so that a hot 
delivery to the boiler is obtained; therefore, for most economical 
results the injector should be at work when the regulator is open, 
the feed being regulated by the water regulator handle on the 
Fireman's side of the cab. 

The "H", "J", "H/J" and "K" types of exhaust injector are 
shown in Figs. 27, 27a, 28, 28a and 29. 

When the regulator is open the injector works with exhaust 
steam in conjunction with a supply of supplementary live steam. 
With the regulator closed, additional auxiliary live steam is necessary 
to take the place of the exhaust steam. 

On all four types of exhaust injector mentioned the changeover 
from exhaust to auxiliary live steam is provided automatically, 
being governed by the pressure in the steam chest. Earlier types do 
not have the automatic control. 

Steam-controlled Exhaust Steam Valve 

When the locomotive is at work with regulator open, the exhaust 
steam valves in the injector are open, admitting exhaust steam to the 
injector; but if the injector is not in use or when the regulator is 
closed, the exhaust steam valves are automatically shut. 

Auxiliary Shuttle Valve 

This valve automatically controls the admission of steam to the 
injector, either exhaust steam or auxiliary live steam, according to 



62 






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r- 

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CONTROL DIAGRAMS 



63 



Engine running 
Injector not working 









Fig. 27 




Engine standing 
or running with throttle closed 
Injector working with live steam 




64 







65 



98 

3 s 



131NI 

wvais isnvHxa 



whether the regulator is open or closed. When the regulator is open 
and exhaust steam available the auxiliary live steam is shut off, but 
when the regulator is closed and exhaust steam is not available, this 
is automatically replaced by a supply of live steam through the 
action of the shuttle valve controlling the supply of steam to the 
auxiliary live steam nozzle. 

Steam-controlled Water Valve 

The water valve is always in the shut position when the injector 
is not in use, but automatically opens immediately the steam valve 
is opened to start the injector. 

The "J"-type exhaust injector differs from the "H" type in the 
following: the two pivoted exhaust steam valves in the 4t H" type are 
replaced in the "J" type by a double-beat spring-loaded valve fitted 
vertically and controlled by a steam piston below the valves. The 
automatic shuttle valve or change-over valve, is fitted below the 
'T'-type injector with the addition of an automatic choke valve to 
regulate the quantity of auxiliary steam supplied to the injector 
when the regulator valve is shut. In the "J" type the automatic 
water control valve has been replaced by a manual-operated disc 
water valve on the body of the injector or above the water entrance 
to the nozzles. This disc valve is fitted directly on to and worked by 
the water regulator spindle and rotated by it. The water valve 
merely acts as a water admission valve and does not regulate the 
quantity of water admitted to the injector cones, which is controlled 
by the movable exhaust steam cone as in the "H"-type injector. 
To shut off the "J"-type injector the steam valve is closed and the 
water regulator spindle moved to the shut position. In the "H;J" 
type the automatic water valve as on the "H" type is fitted to what is 
otherwise a "J" type injector. 

The "K" type of exhaust injector is the latest design to be intro- 
duced and is fitted to the larger B.R. standard design of M.T. 
tender locomotives. In this design the movable exhaust steam cone, 
which has previously been used to control the amount of water 
delivered by the injector, has been replaced by a fixed exhaust 
steam cone and the water supply controlled by a variable water 
valve which is separate from the exhaust injector body but connected 
to it by an intermediate feed-water pipe. This arrangement enables 
both the injector and the water valve to be placed in accessible and 
convenient positions. 

The "K"-type combining cone differs slightly from the previous 
designs in that in addition to the hinged overflow flap there are two 
overflow slots. 



Fig. 27a 



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69 



possible Causes of Injector Failures 

(a) Dirt or scale on the injector cones or excessive wear or 

distortion of the cones. 
(6) Air leaks in water supply. Air drawn in with the feed water 

causing bubbles which break up the jet. 

(c) Insufficient feed water supply owing to an obstruction in the 
tank sieve (as a preventative keep tank lid closed to prevent 
entry of foreign matter); supply valve not properly open or 
tender tank empty. 

(d) Feed water too hot. 

(e) Choked delivery pipe, due to scale. 
(/*) Clack not seating properly. 

(g) Defect in connections to coal watering pipe. 
(/») Some of these defects may allow the injector to work inter- 
mittently or at certain pressures only. Full details of the 
irregularity should be properly described on the "Repair" 
card for the guidance of Fitters, bearing in mind that it is 
not always easy to test an engine over its full range of working 
conditions when the locomotive is stabled in the shed. 
There are few things more annoying to Enginemen than an 
injector which misbehaves on the journey; it is therefore policy to 
make a practice of using both injectors in turn where two live steam 
injectors are fitted. Where an exhaust injector is provided, this 
should not be used during shunting operations when the regulator 
is being continually opened and closed in order to avoid undue 
wear to the change-over valve and risk of scalding staff on the 
ground. 



Blowdown Valves 

Softened water for locomotive purposes is provided extensively in 
some areas of British Railways to reduce scaling and corrosion in 
boilers. In connection with this continuous blowdown valves are 
fitted to locomotives so that a small measured quantity of water is 
drained from the boiler continuously, (1) whilst the regulator is 
open, or (2) whilst the injectors are working. This is done to keep 
down the concentration of soluble salts in the boiler water to 
minimise priming. 

The valve is fitted on the back plate of the firebox, having a con- 
nection above the crown (see Fig. 30). 

In the case of (1), steam from the steam chest actuates a piston in 
the blowdown valve, which in turn lifts a ball valve from its seating, 
allowing boiler water at the rate of about 1-1 i gallons per minute 
to be discharged into the ashpan. On some locomotives (2) the 



70 




DISCHARGE 



STEAM SUPPLY FROM 

STEAM CHEST 

OR INJECTOR STEAM PIPE 



Fig. 30 CONTINUOUS BLOWDOWN VALVE 

blowdown valve is operated by the pressure in either injector 
delivery pipe. 

Carriage-warming Valve 

This valve controls the pressure in the train-heating pipe. 

Cab Fittings 

Fig. 31 shows the arrangement of cab fittings on B.R. Standard 
locomotives. 

Questions and Answers 

(1) Q. What are the principal parts of a locomotive boiler? 

A. Boiler barrel; outer and inner firebox; flue tubes; smokebox 
tubeplate; crown, firebox and longitudinal stays, dome, 
smokebox, superheater, brick arch, ashpan, firedoor and 
fusible plugs. 



71 




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72 






(2) Q. What is the function of the safety valves? 

A. To prevent the pressure of the steam in the boiler from rising 
above the registered pressure of the boiler. 

(3) Q. What is the registered pressure of the boiler? 

A. The steam pressure for which the boiler was designed. This 
is indicated by a metal tablet secured to the firebox back 
plate and also by a red line on the dial of the steam pressure 
gauge. If the steam pressure at which the safety valves lift 
does not correspond within 5 lb. above or below that shown 
on the pressure gauge as registered pressure, the matter 
must be reported. 

(4) Q. Does the escape of steam from the safety valves entail loss? 
A. Yes. It represents a waste of labour, coal and water which 

can largely be avoided by careful management of the fire. It 
is estimated that for each minute the safety valves are open 
the wastage of coal is from 1 to 1 5 lbs. and over 1 gallons of 
water. 

(5) Q. Describe the action of the "Pop" safety valve. 

A. When the registered pressure is reached the spring-loaded 
valve rises and admits a small amount of steam through a lip 
in the valve to the outer annular chamber. This steam 
escapes through holes in the top cap of the valve (Fig. 16). 
The steam on escaping acts on the increased area of the top 
cap and adds to the force which keeps the valve raised till 
such time as the pressure in the boiler falls, when the valve is 
instantaneously closed at slightly below the pressure as that 
at which it opened. 

(6) Q. Where are the water gauges positioned? 

A. The water gauges are mounted on the boiler back plate in the 
engine cab; the bottom gauge cock is so placed that when the 
water level is in sight at the bottom of the glass the crown of 
the firebox is covered with water. When working under 
normal conditions the level of the water should be kept in 
sight in the top half of the gauge glass, and before descending 
severe grades or working over curves with maximum super- 
elevation of rails, a higher water level should be carried. 

(7) Q. What are fusible plugs and where are they situated? 

A. The fusible plugs arc screwed into the firebox crown usually 
about 1 ft. from the firebox tubeplate and about I ft. from the 
firebox back plate (Fig. 7). These brass plugs have a lead 
centre or core which melts at a comparatively low tempera- 
ture. Should the water above the firebox crown fall to a 
dangerously low level, the plug becomes uncovered and the 



73 






lead is melted, thus admitting steam and water into the fire- 
box and warning the Enginemen. 

(8) Q. What action would you take in the event of a melted fusible 

plug? 
A. Put on both injectors to raise the water level in the boiler and 
take immediate steps to remove or deaden the fire. 

(9) Q. What are washout plugs, handhole and mudhole doors and 

for what purpose are they used ? 
A. Washout plugs, handhole and mudhole doors are removed at 
washout period for cleaning and examination of the boiler. 
Washout plugs are fitted on the boiler back plate, smokebox 
tubeplate, sides of firebox and on throat plate, also on top 
side of boiler barrel, near the feed trays, on taper boiler 
engines. Mudhole doors are usually fitted at front and back 
of the firebox just above the foundation ring and at the side 
of the firebox opposite each water space. Handhole doors 
are fitted at side of the firebox above the inside firebox crown. 
(10) Q. Where is the blower valve and ring positioned and for what 
purpose is it used? 
A . The blower valve is generally situated on the boiler back plate ; 
steam from the dome is led to this valve and when the valve is 
opened the steam is carried by an internal steam pipe, passing 
through the boiler, to the smokebox tubeplate, whence it is 
led to the blower ring or casting on top of the blast pipe or to 
a blower ring cast integral with the base of the chimney. On 
B.R. standard locomotives it is mounted below the Driver's 
brake valve away from the boiler back plate so as to be within 
easy reach of the driver (see Fig. 21). The function of the 
blower is to create a partial vacuum in the smokebox when 
the regulator is closed. Whilst working a train or light engine, 
the blower valve must always be opened prior to closing the 
regulator to prevent back draught from the firebox and to 
avoid smokebox gases being induced down the blast pipe, 
especially on entering tunnels. Care should always be taken 
when passing over water troughs to see that the ashpan 
dampers and firedoor are closed (on the train engine) and the 
blower valve opened as a further caution to prevent back 
draught. When the locomotive is standing, the blower may 
be used to avoid smoke and to augment the natural draught 
in the firebox when required to raise steam pressure. 
(11) Q. Describe how the vertical slide valve type of regulator works. 
A. The valve is positioned vertically in the dome (Fig. 20); 
usually the face has four ports, two small ports for starting 



74 






purposes and two large ports for normal running. Resting on 
the valve face is the main valve which has four ports cut in it, 
and the pilot or starting valve rest in turn upon the main 
valve with a flat spring bearing against it. The pilot valve has 
usually two ports which are used for starting purposes. 

The sequence of movements when operating the regulator 
is as follows: first movement of the regulator handle lifts the 
pilot valve until the two small starting ports are open. 
Further movement of the handle then moves both the pilot 
valve and the main valve together, which action opens the 
large ports in the main valve and closes the starting ports. 
During closing, the pilot valve is first moved down over the 
main valve to its normal position, and then both valves are 
brought back to their original position, closing the main ports 
as they come down. 

The independent movement of the pilot valve is obtained 
by the use of a circular hole for the operating pin in the pilot 
valve and elongated hole or slot in the main valve, the result 
being that the latter does not move until the pin has travelled 
a distance corresponding to the clearance in the slotted hole, 
a distance which is equal to the lap plus the port of the pilot 
valve. 

(12) Q. What purpose is served by the continuous blowdown valve? 
A. To keep down the concentration of soluble salts in the boiler 

water on regions where water softening is in use, and this is 
done by allowing a small measured quantity of water to pass 
out of the boiler continuously whilst (a) the regulator is open, 
or (b) whilst injectors are working (Fig. 30). The use of this 
fitting, therefore, will tend to prevent priming. 

(13) Q. What is the purpose of the manual-operated blowdown 

valve? 
A. Whilst the continuous blowdown valve deals with dissolved 
solids in the water it does not assist with the discharge of the 
soft sludge which gradually accumulates in the bottom of the 
boiler barrel and firebox water spaces. To remove this sludge 
some locomotives are fitted with a manual-operated blow- 
down valve positioned just above the foundation ring at the 
centre of the firebox throat plate. This valve is operated by 
hand lever on the right side of the cab, separate instructions 
being issued for its use according to the district in which the 
locomotive may be working. 

(14) Q. What is priming and foaming? What would you do when 

either occurs ? 



75 



A. Priming is produced by certain conditions of the water as 
well as carrying a too high water level, and may be brought 
about by a sudden demand for steam which may result in 
syphoning action or it may be caused by uneven boiling. 
It is distinct from foaming in that it does not originate at the 
steaming surface, but at points below the water line. Foam- 
ing consists of an aggregation of bubbles which carry the 
sediment to the surface of the water. In both cases water is 
carried over with the steam to the cylinders. The more 
serious effects of priming and foaming in locomotive boilers 
are the impairment of lubrication due to water and suspended 
matter passing into the cylinders: interference with the 
proper functioning of the superheater, due to accumulation 
of water which must be evaporated before increase of 
temperature can take place, and in addition the superheater 
elements may be fouled with solid matter. The water 
accumulated in the cylinders may also cause damage to the 
cylinders and motion of the engine. 

When priming and foaming occurs with a low water level, 
open the cylinder cocks, put on the injectors and close the 
regulator gently until the water settles in the boiler to 
ascertain the water level, as there is danger of exposing the 
firebox crown. 

(15) Q. What is the purpose of feed-water treatment? 

A. All natural water contains suspended and dissolved matter, 
the most common being the acid salts of calcium and 
magnesium. Treating boiler feed water brings about the 
precipitation of scale-forming salts which causes the resulting 
suspended matter to be of such form as to be readily removed 
as a sludge, thereby keeping the firebox plates and tubes in a 
much cleaner condition than is the case when untreated 
water containing scale-forming salts is used. 

(16) Q. What is the best system for using injectors? 

A. Where two live steam injectors are fitted they should always 
be used in turn to keep both in working order. 

(17) Q. What depth of water should be maintained in the boiler as a 

good working level? 
A. To maintain the water level in the gauge glass at half to 
three-quarters full is best. This provides a good depth of 
water over the firebox and at the same time leaves plenty of 
steam space. 

(18) Q. What ill-effects will result from having too much water in the 

boiler? 



76 



A. Too high water level in the boiler is bad practice. It restricts 
the steam space and leads to water being carried over with 
the steam, which may cause such troubles as damaged 
cylinders and pistons, bent connecting rods, possible diffi- 
culty in releasing the vacuum brake, and injector troubles. 

(19) Q. Explain the working principles of a movable combining-cone 
type of injector. 

A. Fig. 25 shows this injector which is usually placed vertically 
at the inside of the trailing engine footstep. A jet of steam 
emerging at high velocity from the (top) steam cone is 
brought into contact with the cold feed water which is 
admitted round the tip of the steam cone. Partial condensa- 
tion of the steam jet takes place, a partial vacuum is formed, 
and the water is forced forward at considerable speed into 
the wide end of the converging combining cone. Passage 
through this cone completes the condensation of the steam, 
producing a high vacuum, and the water emerges from the 
small end of the cone at greatly increased velocity. The 
water jet then passes the overflow gap and enters a diverging 
cone known as the delivery cone. 

The shape of the delivery cone causes the speed of the flow 
to be quickly and considerably reduced, which process 
converts the energy of motion in the water into pressure 
energy at the outlet end of the delivery cone. The pressure 
developed in this way at the delivery end of the injector 
exceeds the boiler pressure sufficiently to enable the feed 
water to lift the clack valve against the steam pressure and 
enter the boiler. 

The vacuum developed in the combining cone when the 
injector is working is used to hold a movable section of the 
cone up against the top portion, giving the effect of a con- 
tinuous cone. If the action of the injector is interrupted or 
the water jet upset, the vacuum in the cone is replaced by 
pressure, the moving section is then forced away from its 
seating and any surplus steam and water escapes through 
the gap so formed, to the overflow outlet. When the pressure 
has been relieved the working vacuum rapidly re-establishes 
itself and the injector will then restart. In some types of 
injectors the moving cone is replaced by a hinged flap 
forming one side of the combining cone. In this case the 
flap is forced open when the injector "flies off". Injectors 
with sliding cone or hinged flap are known as automatic 
restarting injectors. 



77 



(20) Q. What is the purpose of the exhaust steam injector? 

A. To provide an economical method of injecting water into the 
boiler by utilising steam from the blast pipe for this purpose. 
Exhaust steam also heats the feed water so that a hot feed is 
obtained. For best results the injector should be at work 
when the regulator is open, the feed being regulated by the 
handle provided. The hottest feed is obtained when the feed 
handle is in the "minimum" position. 

(21) Q. Name the cones in the exhaust injector. 

A. Supplementary live steam cone, movable exhaust steam cone 
for regulating water supply (except in the "K" type), draft 
tube, vacuum tube, combining cone and delivery cone. 
There is also the auxiliary live steam nozzle, and ports 
around the supplementary cone. 

(22) Q. What are the main differences between the "H" and "J" 

types of exhaust steam injectors? 
A. The two pivoted exhaust steam valves in the "H" type are 
replaced in the "J" type by a double-beat spring-loaded 
valve fitted vertically and controlled by a steam piston below 
the valve. The automatic shuttle valve or change-over valve 
is fitted below the "J"-type injector with the addition of an 
automatic choke valve to regulate the quantity of auxiliary 
steam supplied to the injector when the regulator valve is 
shut. In the "J" type the automatic water control valve has 
been replaced by a manual-operated disc water valve on the 
body of the injector above the water entrance to the nozzles. 
This disc valve is fitted directly on to and worked by the 
water regulator spindle and rotated by it. The water valve 
merely acts as a water-admission valve and does not regulate 
the quantity of water admitted to the injector cones, which is 
controlled by the movable exhaust steam cone as in the 
"H"-type injector. To shut off the "J"-type injector the 
steam valve is closed and the water regulator spindle moved 
to the shut position. 

(23) Q. What is the "H/J" exhaust steam injector? 

A. This is an exhaust injector of the "H" type retaining the auto- 
matic water control valve but embracing the front or live and 
exhaust steam portion of the "J" type, i.e. the casting con- 
taining the exhaust steam control, change-over control 
system and automatic choke valve. The main body of the 
injector, containing the cones, automatic water valve and 
details of the "H" type, is retained. 



78 






(24) Q. How would you test the automatic change-over in the exhaust 

steam injector? 

A. To test the automatic change-over from live steam to exhaust 
steam and vice versa apply engine brake with engine standing, 
start injector working and then open engine regulator. If the 
automatic shuttle valve functions properly the injector will 
stop working and water will run out of overflow. Then close 
the regulator and open the cylinder cocks. When pressure has 
escaped from the engine cylinders the injector will immedi- 
ately work. If the injector does not operate as described and 
continues to work with the regulator open, the automatic 
shuttle valve does not function. Either a restriction will be 
found in the auxiliary steam pipe from the steam chest to the 
injector or the automatic check valve does not seat properly. 

(25) Q. If the auxiliary control pipe from the steam chest breaks 

while running, what should be done? 

A. If possible, carry on to first stopping point then blank off the 
pipe at a union or close isolating cock where fitted; if unable 
to do this, flatten the pipe on the steam chest side of the 
fracture. The injector will still work on live steam with this 
pipe blanked off. If the exhaust steam pipe, from the blast 
pipe to the injector, fractures whilst running, the auxiliary 
control pipe from the steam chest would have to be blanked 
off to allow the injector to operate with live steam while 
regulator valve was open, although injector would work 
normally with regulator closed. 

(26) Q. If one of the top feed clacks sticks up when working a train, 

what steps would you take? 

A. Immediately put on the opposite injector and then note 
whether the boiler will supply the demand for steam required 
to work the train in addition to the loss from the sticking 
clack. If it will not, the train should be stopped at next point 
where it can be placed under protection of fixed signals, 
where steps should be taken to re-seat the clack. To do this, 
close the tank or tender feed valve and the blow-back steam 
will exhaust at the injector overflow; open the water regulator 
valve wide; open the injector steam valve fully to expel the 
blow-back steam and to create a partial vacuum in the 
injector body; open the tank feed quickly and the injector 
should pick up the water and, when regulated, the delivery 
will disturb the clack which should re-seat when the injector 
is shut off. 



79 



(27) Q. If your engine is giving trouble with leaking tubes or stays, 

what is the best procedure to adopt? 
A. In this case the Driver should do all in his power to ease the 
demand on the boiler and assist the Fireman by working the 
engine as lightly as possible. It is better to lose a few minutes 
in running than to come to a forced stop in a section, thereby 
causing heavy delays by having to carry out Protection Rules. 
The Fireman should exercise the greatest care in manipula- 
tion of the injector, dampers and firedoor, in order to main- 
tain the firebox temperature as steady as possible. 

(28) Q. Name several preventable causes of engines not steaming. 
A. Dirty firebox tubeplate, tubes blocked up, leaking joints in 

smokebox, tubes leaking, blast pipe out of alignment with 
chimney, smokebox door drawing air (not properly tightened 
up), defective brick arch, defective dampers, valves and 
pistons blowing through, inefficient firing, badly fitting 
baffle plate and choked ash plate (spark arrester) in smoke- 
box of the self-cleaning type. 






80 



SECTION 5 



VALVES AND PISTONS 



The steam locomotive is the means of converting the heat energy 
contained in the fuel into useful work by driving the pistons, the 
reciprocating motion of these being converted into the rotary motion 
of the driving wheels by the piston rod, connecting rod and cranks. 

When the regulator valve is opened, steam generated in the boiler 
passes through the internal steam pipe (and superheater when fitted), 
through the external steam pipe to the steam chest, where the supply 
of steam to the cylinders is regulated by the action of the valves, 
In the cylinders the steam expands and does useful work on the piston 
before escaping into the atmosphere. 

The locomotive valve of any kind must, in conjunction with the 
valve gear, so control the valve that the following events take place 
in succession in the cylinder: — 

(a) A period of admission of live steam up to a point of cut-off. 

(b) A period of expansion up to a point of release. 

(c) A period of release for the used steam. 

(d) A period of compression after the valve has closed. 

(e) A brief period of pre-admission of live steam before the piston 
commences its working stroke (see Fig. 32). 

In the events just indicated the valve has three distinct duties to 
perform : — 

(a) closes both steam ports when in its central position; 

(b) admits steam to one end of the cylinder only at one time; 
(<■) opens to exhaust at one end of the cylinder at least as soon 

as it opens to admit steam at the other. 

Figs. 33 and 33a show sections through steam chests in which slide 
and piston valves operate. The face on which the valve slides has 
three ports, the end ports "A" lead one to each end of the cylinder, 
the larger centre port "C" leads to the exhaust passage. In the 
position shown in the bottom figure, steam from the steam chest is 
passing the edge of the valve into the left-hand steam port, exerting a 
pressure, driving the piston to the right. On the other side of the 
piston steam is escaping by way of the right-hand steam port, 
through the cavity in the slide valve to the exhaust passage. 

The relative positions of the valve and piston (ordinary "D" slide 
valve and inside admission piston valve) for one revolution of the 
wheel are shown in Fig. 34. 

It will be noted that the slide or piston valve controlling the 



ADMISSION 



EXPANSION 



LEAD STEAM 




EXHAUST 



COMPRESSION EXHAUST 

-< m 



' A. POINT OF ADMISSION 

B. POINT OF CUT OFF 

C. POINT OF RELEASE 

D. POINT OF COMPRESSION 



Fig. 32 DIAGRAM SHOWING THE DISTRIBUTION OF 

STEAM ON ONE SIDE OF THE PISTON 

FOR A DOUBLE STROKE 

admission and exhaustion of steam to and from the cylinders has its 
face of such breadth that when the valve is in mid position it com- 
pletely closes both steam ports. Two more important items have to 
be considered now — the "lap" and "lead" of the valve. "Lap" is 
the amount by which the valve overlaps each steam port at the 
middle position of each valve. There arc actually two kinds of 
lap: "steam lap" is the amount by which the valve overlaps the port 
on the live steam side; similarly, the "exhaust lap" is the amount by 
which the valve overlaps the port on the exhaust side. "Exhaust 
lap" is generally given to slow-running locomotives, i.e. those 
designed for shunting duties, the effect being to delay the exhaust 
and derive the maximum work from the expanding steam in the 

cylinder. 

"Negative exhaust lap", or as commonly termed "exhaust 
clearance" (Fig. 33), is the amount the port is open to exhaust when 



81 



82 



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83 



VALVE IN MID-POSITION 

EXHAUST EDGE 
STEAM EDGE 



VALVE IN MID POSITION 




STEAM INLET 



OUTSIDE LAP 




EXHAUST PORTS 



VALVE FULLY OPEN TO STEAM 



STEAM 
EXHAUST 
TEAM 




VALVE FULLr OPEN TO STEAM 



STEAM PORTS 




SLIDE VALVE 
AND STEAM CHEST 



PISTON VALVE 
AND STEAM CHEST 



Fig. 33a 



the valve is in mid-position, and this is used on many fast-running 
locomotives to give a free exhaust. The amount seldom exceeds 
A in. when exhaust clearance is given; the cylinder on both sides of 
the piston is open to exhaust at the same time when the valve is 
passing through the mid-position, which is only momentary when 
running. 

The "lead" of the valve is the amount by which the steam port is 
open when the piston is static at front or back dead centre. 
Pre-admission of steam fills the clearance space between the cylinder 
and piston and ensures maximum cylinder pressure at the commence- 
ment of the stroke. "Lead" is particularly necessary on locomotives 
designed for high speeds, under which conditions the valve events 
are taking place in rapid succession. 



84 



INSIDE ADMISSION 









\\ N NN , \\\\ 







S 



OUTSIDE ADMISSION 



VALVE 








\fpEST 





CRANK POSITION 



e 



e 



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Fig. 34 VALVE EVENTS 
FOR ONE REVOLUTION OF WHEEL 



85 



Fig. 35 ECCENTRIC CRANK AND RETURN CRANK 




ECCENTRIC CRANK 



RETURN CRANK 



The eccentric (Fig. 35) is used to convert the rotary motion of 
the crank axle into the reciprocating motion required to operate the 
valve. If we imagine a "D"-type slide valve without "lap" and not 
given "lead" it would, when the piston is at the end of its stroke, 
just cover the steam ports and be in the central position, i.e. mid- 
stroke. The eccentric operating the valve would also be in 
mid-position and set at 90° (a right-angle) in advance of the crank. 
From this position the valve would commence to open. 

The eccentric is equivalent to a small crank, the length of whose 
arm "R" is the same as the distance between the centre of the 
eccentric sheave and centre of shaft. The length of "R" is called the 
eccentricity of the eccentric, and the valve travel is equal to twice the 
eccentricity. The return crank gives an equivalent movement to 
that of the eccentric and describes a circle of radius equal to distance 
"R" between the centre of the shaft or axle and the centre of the 
return crank pin. 

If "steam lap" is added to the valve it would overlap the port by 
the amount of "lap" and if the eccentric were set as described above, 
steam would not be admitted to the cylinder until the piston had 
travelled some distance from dead centre and the engine would not 
work properly. To overcome this difficulty and to admit steam 
through the steam port to behind the piston immediately it moves 
from dead centre, the valve must be set ahead of the crank by 
90° plus the "steam lap" (see Fig. 33). It is necessary also, as we 
have previously stated, to provide "lead" and this is done by moving 
the eccentric still further in advance of the crank; the eccentric has 
therefore been moved through a total of 90° plus "lap", plus "lead", 
the angle in excess of the right-angle being known as the "angle of 
advance". 



86 



It should be remembered that only the "lap" is apparent on the 
valve, the "lead" being a portion of the port opening, but both the 
"lap" and "lead" are apparent on the setting of the eccentric. 

From mid-position the travel of the valve is equal to the "lap" 
plus the steam port opening, this being equal to the throw of the 
eccentric or the radius of eccentricity (see Fig. 35). 

Twice the throw of the eccentric will be equal to the full travel of 
the valve, just as twice the throw of the main crank equals the stroke 
of the piston. Whilst the "lead" affects the angular advance of the 
eccentric it does not affect the travel of the valve. 

The piston valve (Figs. 33 and 33a) consists of two circular pistons 
fixed the necessary distance apart on a spindle; the whole assembly 
reciprocates in a cylindrical steam chest. The valve heads are each 
fitted with rings to maintain a steam-tight fit in the steam chest. 
Piston valves can be adapted for inside or outside admission of 
steam to the cylinders. With inside-admission piston valves the live 
steam is contained between the two heads and is admitted to the 
steam ports at the inner edges of the valve heads, being exhausted at 
the outer edges into separate exhaust passages which combine to 
communicate with the blast pipe. 

With outside-admission piston valves the steam is contained 
outside the valve heads with a common exhaust chamber between 
the heads, steam entering the ports at the outer edges of the valve 
heads and being exhausted at the inner edges. 

With this arrangement the valve spindle glands are subjected to 
high-pressure steam at high temperature in the case of superheated 
locomotives and for this reason modern locomotives are almost 
invariably of the inside-admission type. Exceptions are the former 
S.R. Merchant Navy and West Country classes which have outside- 
admission valves, but which employ steam chest rocking shafts in 
place of valve spindle glands, as shown in Fig. 50. The modified 
former S.R. "Pacific's" have normal Walschaert valve gear, but whilst 
the inside cylinder has inside admission the outside ones have outside 
admission. 

With inside-admission piston valves the travel of the valve is 
opposite that of the slide valve and outside steam admission piston 
valve; thus, to admit steam to the front port the valve must be 
moved forward to allow steam to pass the inside edge of the front 
valve head, i.e. in a direction opposite to that of the cylinder piston. 
The setting of the eccentrics in each case is shown in Fig. 35A. 

When using a direct-acting link motion with inside-admission 
piston valves the eccentric requires to be set an additional 180° in 
advance of the crank to that used for outside admission, which 
position is actually following the crank by 90° minus "lead". 



87 



Inside-admission piston valves actuated by means of a rocking 
shaft, which reverses the direction of travel of the valve motion, 
require the eccentrics to be set as with direct motion with slide valves. 

The maximum travel of the slide or piston valve is twice the 
"steam lap" plus twice the port openings. The minimum travel is 
twice the "lap" plus twice the mid-gear "lead". 

The chief points affecting steam flows are valve travel, the diameter 
of the piston valves, together with the shape and layout of the steam 
chest and port passages. 

The width of the steam ports in the valve liner is dependent upon 
the travel: the longer the travel, the wider the ports can be made. 
The extension of the steam chest beyond the ends of the cylinder 
barrel enables the piston valve heads to be widely spaced so that the 



ANGLE OF ADVANCE 



Position of eccentrics 
for "Direct Motion" 
or "Indirect Motion" 
with Inside Admission 



Position of eccentrics 
for "Indirect Motion" 
or "Direct Motion" 
with Inside Admission 




CRANK 



CRANK 



ANGLE OF ADVANCE 



Fig. 35a POSITION OF ECCENTRICS 



88 



steam ports can be located directly at the ends of the cylinder bore, 
allowing direct passages between the valve ports and the cylinder. 

The term "long travel" is actually a "long lap" valve, the increased 
steam lap being greater in proportion than the increase in valve 
travel. The chief advantage derived from long-lap valves is greater 
exhaust freedom and earlier cut-off working, the valve moving a 
greater distance for a given angular movement of the crank. The 
initial movement of the valve is accelerated, being the valve events 
of admission, expansion, exhaustion and compression more sharply 
defined. The port opening to steam is increased and both the 
exhaust and compression delayed, at the same time the greater port 
opening to exhaust provides a free exhaust at high speed and a 
decrease in back pressure. 

The slide valve has an advantage over the piston valve in that it 
will lift off the port face to release water which may have accumu- 
lated in the cylinders when standing, and although pressure relief 
valves are fitted to the cylinders of locomotives fitted with piston 
valves, they are not designed to deal with large quantities of water. 

Locomotive pistons are of various types. There are, for instance, 
the "box" type which is manufactured of cast iron and the "dish" 
type which is made of cast iron or steel. On former L.N.E.R. 
standard locomotives^ the piston and rod are in one piece, being 
made of steel forged or welded. 

Modern pistons are fitted with two or three narrow rings about 
-& in. in width. A B.R. standard design of piston head is shown in 
Fig. 36. 



TAPPED HOLE FOR 

WITHDRAWAL 

PURPOSES 



PISTON ROD COLLAR . 
AND DOWEL \ 



COLLARED NUT 
LOCKING PLATE 
LOCK NUT 




PISTON ROD 
PISTON RINGS 



PISTON-HEAD CARRIER-— ^CARRIER SPRINGS 

Fig. 36 PISTON HEAD 







89 






Cylinder drain cocks are fitted to drain away any accumulation of 
water from the cylinders and steam chest. Three drain cocks are 
fitted to each cylinder casting, one at each end of the cylinders and 
one connected to the steam chest. Cylinder cocks should always be 
open when the locomotive is standing or at any time when there is 
an indication of water in the cylinders. Steam-operated cylinder 
cocks are fitted to some of the B.R. standard locomotives (see 
Fig. 37). 



VALVE OPEN 
(CYLINDER COCKS SHUT) 

60° 



VALVE SHUT 
^ (CYLINDER COCKS OPEN) 




TO DRAIN 



CYLINDER DRAIN COCK 




OPERATING 
LEVER 

GLAND NUT 

STUFFING BOX 

OPERATING SPINDLE 

CYLINDER COCK BODY 

PISTON-TYPE VALVE 

PACKING SPACER WASHER 



FROM ACTUATING 
VALVE 

4 - 



^INSPECTION CAP 
PISTON PACKING 



CAP NUT AND SIEVE 



SPRING 



Fig. 37 STEAM-OPERATED ACTUATING VALVE 
AND CYLINDER DRAIN COCK 



Most locomotives with piston valves are fitted with one or more 
anti-vacuum valves which automatically admit air to minimise the 
partial vacuum created in the cylinders and steam chests when 



90 






coasting with the regulator closed. Under these conditions the valves 
and pistons in the cylinders act like pumps, tending to induce air 
from the steam chest, which action rapidly creates a partial vacuum 
inside the steam chest, the amount being further increased by the 
cylinders during what would be the normal "expansion" portion of 
the stroke, with the result that when the valve opens to exhaust, 
smokebox gases and possibly ashes may be drawn down the blast 
pipe to destroy the vacuum. Additionally, during the compression 
portion of the stroke very high temperatures are reached which 
cause lubrication difficulties. To counteract these effects anti- 
vacuum valves are fitted. These may be placed either on the steam 
chest or be connected to the saturated side of the superheater header 
and their effect is to admit air and partially destroy the vacuum in the 
steam chest (see Figs. 38 and 39). It will be appreciated that these 
valves are more effective at slow speeds and long cut-offs, i.e. when 
the expansion and compression periods of the stroke are the shortest. 
It is not satisfactory, however, to run at high speeds with the valve 
gear in full travel, nor would the anti-vacuum valves admit sufficient 
air to be effective. When coasting under these circumstances a 
breath of steam should be supplied to the steam chest by cracking the 
regulator, i.e. slightly opening and placing the reversing gear in the 
best position for the type of locomotive. For locomotives fitted 
with poppet valves there are special instructions. 

Questions and Answers 

(1) Q. How is the drive conveyed from the pistons to the wheels? 
A. The drive from the piston is conveyed to the wheels by way of 
the piston rod, crosshead, little end, connecting rod, big 
end and the crank. The connecting rod and crank convert 
the backward and forward movement of the piston into the 
rotary movement of the axle and wheel. 

In forward gear the pistons push the crank pins under the 
axle and pull them forward over it, while in back gear the 
crank pins are pushed over the axle and pulled forward 
under it. 

The slide bars or guides prevent the oblique thrust of the 
connecting rod from bending the piston rod. For example, 
if the crank is on the top quarter and the piston being 
propelled forward as in fore gear, the resistance of the crank 
causes an upward thrust in the connecting rod which is 
transmitted to the slide bars. The thrust of the piston rod 
crosshead being against the top slide bar when running 
forwards and against the bottom bar when running back- 
wards, with regulator open. 












91 



VALVE CLOSED 
VALVE OPEN 




TO STEAM CHEST ( '*"- J 



ta^^^S^ 



Fig. 38 ANTI-VACUUM VALVE 
MOUNTED ON STEAM CHEST 



eob ra d 





VALVE CLOSED 
VALVE OPEN 



Fig. 39 ANTI-VACUUM VALVE 
MOUNTED ON SUPERHEATER HEADER 



92 



When the crank pin drives the piston, as when coasting, 
the direction of the thrust on the slide bar is reversed. The 
amount of thrust varies with the angularity of the connecting 
rod, being greatest at about half stroke when the crank and 
connecting rod are at right-angles to each other, being 
reduced to zero at the dead centre, hence the increased wear 
in the middle of the slide bars. 

(2) Q. What are the eight named positions of the crank? 

A. The forward and backward crank position in which the 
crank pin, connecting rod and piston are all in a straight 
line are known as the front and back dead centres. When the 
crank pin stands at right-angles to the centre line, upwards 
or downwards, it is said to be on the top or bottom quarter. 
The four intermediate settings which lie mid-way between 
the front and back dead centres and the top and bottom 
quarters are known respectively as the front and back top 
angles and the front and back bottom angles (see Fig. 40). 

(3) Q. Does the position of the crank supply any clue to the 

position of the piston in the cylinder? 
A. Yes. By reference to the eight crank positions described in 
the previous question it is quite easy to visualise the position 
of the piston within the cylinder. For instance, when the 
crank is on front or back dead centre the piston will be at 
the end of its stroke at the front or back of the cylinder, when 
the crank is on the top or bottom quarter the piston will be 
approximately at mid-stroke. With the crank on top or 
bottom front angle the piston will be rather less than 
quarter stroke from the front of the cylinder and rather less 
than quarter stroke from the back cover when the crank is 
on either of the two angles. 

(4) Q. What is the relation between the events in the steam cycle 

and piston position? 
A. The duration of the various periods of steam in the cylinder is 
generally measured in terms of the piston stroke, for 
instance, when we refer to cut-off at 50% or 75%. It is, 
therefore, possible to state where the piston will be when 
the events of cut-off, release, compression and admission 
occur. Consequently it is only one step further from this to 
be able to couple the cylinder events with the crank settings 
to enable the valve position to be judged from the setting of 
the cranks or side rods. 

(5) Q. The steam action in the cylinder has been explained in 

relation to the piston movement. Can you explain it in 
relation to the crank positions? 



93 



TOP 

FRONT 
ANGLE 



TOP 
BACK 



ANGLE 



FRONT 
QUARTER 




POSITION OF PISTON 
WHEN CRANK IS ON FRONT DEAD CENTRE 



Fig. 40 LEAST-EFFORT POSITION OF CRANK 



A. In forward gear the front side of the piston is exposed to 
live steam during admission and expansion periods and the 
rear side is exhausting as the crank moves under the axle 
from front dead centre to back dead centre. After the crank 
passes back dead centre position the back of the piston takes 
admission steam followed by expansion and the front side 
of the piston enters upon the exhaust and compression 
periods. 

In back gear steam acts in front of the piston as the crank 
passes over the axle and behind the piston as the crank 
moves forward under the axle. 



94 



(6) Q. What is the effect of notching up the gear upon the steam 

cycle with the cylinder? 
A. Notching up shortens the valve travel, this having the effect 
of shortening the admission period and lengthening the 
expansion and compression periods. 

(7) Q. Whert the crank is on top or bottom position the piston would 

be approximately at mid-stroke. Why do these positions of 
the crank not place the piston exactly at mid-stroke? 
A. This effect is produced by the angularity, the piston will 
occupy the exact centre of the cylinder barrel only in the 
crank positions where the angle between the centre line of the 
crank pins and the centre line on the connecting rod is equal 
to 90°, this will occur when the crank pin is slightly in advance 
of the top and bottom quarter positions. 

The extent of this angularity effect depends upon the length 
of the connecting rod and the throw of the crank and is 
increased when short connecting rods are used. Allowance 
has to be made for this effect in the valve gear, otherwise 
steam distribution would be adversely affected. 

(8) Q. Describe in detail a typical steam cycle in the front end of the 

cylinder during one revolution of the driving wheels, the 
gear being in a position giving about 30% cut-off. 
A. Commencing from the dead centre the piston will travel about 
30% of its stroke before the valve closes the front port to 
steam and cut-off occurs. Expansion will occupy a further 
45% of the stroke, at which point the exhaust edge of the 
valve will uncover the front port to exhaust giving the point 
of release, the piston then completes the remaining 25% of 
the backward stroke with the front port open to exhaust. 
The piston will now make about 70% of the return stroke 
before the exhaust edge of the valve again closes the front 
port starting the period of compression. This will occupy 
about 25% of the return stroke, at which point the" steam 
edge of the valve clears the front port, once more opening it 
to lead. This is the period of pre-admission which occupies 
the remaining 5% of the return stroke until the piston 
reaches the front dead-centre position in readiness for the 
commencement of the next cycle (see Fig. 32). 

(9) Q. What is occurring in the back of the cylinder during the 

same period ? 
A. Starting from the front dead centre the valve already has the 
back port open to exhaust, which continues until the piston 
has covered 70% of the backward stroke, when the valve 




95 



closes the back port and compression commences. This 
occupies a further 25% of the stroke, when the steam edge of 
the valve will uncover the back port to lead and the period of 
pre-admission sets in to occupy the remaining 5% of the 
backward stroke. The piston now returns from the back 
dead centre and will cover about 30% of the return stroke 
before cut-off occurs at the back port. Expansion then follows 
for another 45% of the stroke, after which the back port is 
again opened to exhaust and release occurs, lasting over the 
remaining 25% of the stroke until the piston reaches front 
dead centre. 

(10) Q. How can you tell which crank leads? 

A. The engine should be set with one big end on the top quarter 
and if the other big end is then on the front dead centre the 
latter crank leads, if on the back dead centre it follows. 

(11) Q. How should a locomotive be set in order to test the valves 

and pistons on one side? Describe the procedure. 
A. The crank of the cylinder under test should be set on the top 
or bottom quarter, the reversing lever placed in mid-gear and 
the regulator opened slightly with the steam and hand brake 
on and the cylinder cocks closed. 

The test is made by moving the reversing lever as required 
from forward to backward gear and noting the indications 
given at chimney or cylinder cocks. 

If on going into full forward gear a blow is heard from the 
chimney which ceases in mid-gear and restarts in back gear, 
leakage past the piston will be indicated. 

A continuous blow up the chimney obtained in all posi- 
tions of the reversing lever would indicate that the valve 
under test was blowing through, but on two-cylinder loco- 
motives this effect would also be produced by a defective 
piston on the opposite side, and therefore if this indication is 
obtained, reset the engine and test the other cylinder in order 
to prove the opposite piston before coming to any decision. 

(12) Q. What indication would be given by this test if the valves and 

pistons were in good order? 
A. In this case no blow will be heard from the chimney in any 
position of the gear, but a single and well-defined beat will be 
heard as the gear is reversed from forward to back gear and 
vice versa. 

(13) Q. How would you test for a broken valve lap on a slide valve 

engine or admission steam rings on a piston valve engine? 
A. This may be found with big end on bottom quarter setting as 
described above, but the cylinder cocks should be left open. 



i 



96 






If on moving the reversing gear a short distance towards 
forward gear steam blows from the front cock, or from the 
back cock when the reversing gear is moved a short distance 
toward back gear, this indicates that a portion is broken off 
the front or back valve lap respectively. In the case of a 
piston valve a broken ring or damaged steam edge of the 
valve would be indicated. In the case of badly damaged laps, 
a blow from either of the cocks may be obtained with the 
lever in mid-gear according to which lap is affected. The 
front laps may also be tested with cranks set on the front 
angles and the back laps with cranks set on the back angles 
if desired. 

(14) Q. Describe the principle of the angles tests using front angles 

setting. 

A. In this position two crossheads will be level in the slide bars 
next to the front end, and with the reversing gear in mid- 
position both front ports will be just covered by the steam 
edges of the valves, whilst the two back ports will be open to 
exhaust. In forward gear the R.H. valve will uncover the 
front port to steam and will maintain the back port to ex- 
haust. The L.H. valve will open the front port to exhaust and 
will close the back port. In backward gear the R.H. valve 
opens the front port to steam and the back port to exhaust. 

(15) Q. If your engine was suspected of having a cracked valve cavity 

or defective piston valve rings, causing a bad blow through 
to exhaust, could you ascertain which valve was at fault? 
A. Yes. This could be ascertained by employing the mid-stroke 
tests with crank on top or bottom quarter, but it would be 
advisable to test both sides. In this test the cylinder cocks 
should be used and when the defective side is tested steam 
will be found to issue from both front and back cylinder cocks 
when the gear is in forward and backward gear. In forward 
gear a heavy blow will be obtained from the front cock and a 
light blow from the back, whilst in back gear the back cock 
will blow heavily and the front one lightly. On former 
G.W.R. locomotives fitted with piston valves the test required 
is slightly different as the valves are fitted with only two rings 
on each head, i.e. one steam and one exhaust. In this case the 
suspected side should be placed with big end on the bottom, 
cylinder cocks open, brake hard on, reversing lever in mid- 
gear. With the regulator open, steam from the front cylinder 
cock indicates that the front steam ring is defective. No 
steam from either cylinder cock indicates that steam rings on 
both heads are good. 



97 



Close cylinder cocks and put reversing lever into full 
forward gear, open regulator to fill front end of cylinder with 
steam and then shut. Bring back reversing gear nearly to 
mid-gear and retain in this position for a few seconds. In 
this position the exhaust ring is on the exhaust side of the 
port, thus keeping the steam in the cylinder. If steam is 
blowing through to exhaust in this position no beat will be 
heard up the chimney when the reversing lever is moved into 
back gear; the front exhaust ring is defective. If, however, 
a good beat is heard when the reversing lever is placed into 
back gear the front exhausting ring is good. By placing the 
lever into back gear and then following the same procedure 
the back exhaust ring may be tested. 

Note: A blow up the chimney in both fore and back gear 
would indicate a defective piston. 

(16) Q. How can the valves and pistons be tested on a three-cylinder 

simple engine? 
A. Each cylinder should be tested separately by the mid-stroke 
method with crank on top or bottom quarter. Another 
method is to test each piston separately with its crank on 
front or back dead centre. By this method a defective piston 
will be disclosed by a continuous blow up the chimney in all 
positions of the lever when the regulator is opened, because 
one port will be open to lead and the other to exhaust. If the 
piston is sound there will, of course, be no blow of any 
kind. Whichever method is used, all three pistons must be 
tested in turn and the results noted before any decision is 
formed as to where the defect lies, because it is possible to 
be misled from a single test if defects exist in one or both of 
the other two cylinders. 

(17) Q. How can a four-cylinder simple engine be tested for valves 

and pistons? 
A. In this case also the mid-stroke setting should be used, but 
it has to be realised that the adjacent inside and outside 
cylinder will be tested simultaneously due to the fact that 
their respective cranks are fixed on opposite centres. 






98 









SECTION 6 
VALVE GEARS 

We have seen from the previous section that a slide or piston 
valve actuated by one eccentric will rotate the driving wheels in one 
direction, but, as it is essential that the engine must work in both 
directions, additional valve gear becomes necessary. 

Two-cylinder locomotives are constructed with the cranks set at 
right-angles to each other, one piston exerting its greatest effort whilst 
the other, on its dead centre, will not exert any rotating force on its 
crank. The piston on the front or back dead centre must receive 
steam at the end of the cylinder and travel away from the cylinder 
cover irrespective of whether the engine moves forward or back- 
ward. The other piston at mid-stroke will receive steam either at the 
front or back and will move in the direction of the force exerted, 
which will determine whether the engine moves forward or backward. 
The function of the slide or piston valve is to distribute the steam to 
the cylinder and that of the valve gear to control the valve events 
in correct sequence. 

The Stephenson Valve Gear 

This type of valve motion, as shown in Fig. 41, employs two 
eccentrics, fitted to the crank axle, for each valve, one eccentric for 
fore- and one for back-gear working. 

The backward and forward movement of the eccentrics is trans- 
mitted through the eccentric rods to a slotted link known as the 
expansion link, the fore-gear eccentric rod being coupled to the top 
and the back-gear rod to the bottom of the link. The links are 
suspended from a common reversing shaft by lifting links and may 
be raised or lowered at will from the reversing gear in the cab 
through the medium of the reversing rod. 

Fitted in the slot of the expansion link is a die block, which is 
connected to the valve spindle by an intermediate valve rod. When 
the link is lowered to bring the fore-gear eccentric rod into line or 
almost in line with the intermediate valve rod or spindle rod, the 
movement of the eccentric is transferred to the valve. Conversely, 
if the link be raised, the movement of the back-gear eccentric rod 
will be transferred to the valve. With the link placed so that the 
die block is in the centre of the link, the mid-gear position, the link 
simply oscillates about the die block with a to and fro movement 
equal to the steam lap plus the lead of the valve, from its central 



99 










Fig. 41 



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Fig. 43 STEPHENSON VALVE GEAR 
DIAGRAM SHOWING VARIATION IN LEAD 



VALVE ROD 



MID GEAR 



CRANK 




DECREASE IN LEAD 

FROM MID TO 

FULL GEAR 



DIAGRAM OF VALVE LEAD 



In Stephenson's Gear with Rods as shown in the sketch the valve head gradually 
increases as the gear is notched up from Full Backward or Full Forward to Midgear 
and becomes a Maximum in Midgear. This is owing to the control of the valve by 
the eccentrics having a varying effect from Midgear to Full Forward or Backward 
Gear. At Midgear both eccentrics exercise effect on the movement of the valves 
giving Maximum Lead. When Full Forward or Full Backward Gear is approached 
one eccentric exercises a decreasing control and the other eccentric an increasing 
control until Full Gear is reached. The forward eccentric has Full Control in 
Forward Gear and the backward eccentric Full Control in Back Gear giving 
Minimum Lead. 



position. The full travel in mid-gear position is equal to twice the 
steam lap plus twice the mid-gear lead. 

Intermediate positions of the die block in the link will allow for 
a variation of valve travel, according to the position of the reversing 
gear, varying the cut-off of steam to the cylinders and making use 
of the expansive property of the steam. 

With the arrangement of the Stephenson link motion, as shown in 
Figs. 41 and 42, the lead of the valve increases as the gear is 
"notched up" to a maximum at mid-gear and a minimum at full 
forward or full backward gear. Fig. 43 illustrates the variation of 
lead for mid- and full-gear positions; the increase of lead at early 
cut-off positions is advantageous at high speeds. 



Fig. 42 



102 



103 



BC 

< 
111 

5 

5 



3 

I 
U 

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Fig. 45 ARRANGEMENT FOR 
WALSCHAERT VALVE GEAR 



With outside-admission valves (slide and piston) actuated directly 
by Stephenson valve gear, the position of the eccentric on the crank 
axle is 90° plus the angle of advance in front of the crank for each 
direction of travel. 

With inside-admission valves operated directly, the respective 
eccentrics follow the crank by 90° less the angle of advance. 

If a rocking shaft, which reverses the direction of movement, is 
interposed between the inside-admission valve and the valve gear, 
the eccentrics are set as mentioned in the first example. 

The Walschaert's Valve Gear 

With this type of valve gear the movement is derived from two 
distinct sources, as follows: — 

(a) A single eccentric or return crank, eccentric rod or return 
crank rod, expansion link and radius rod (Fig. 44) which 
provides for the movement of the valve equal to twice the 
steam port opening, the expansion link being provided for 
varying the cut-off and reversing the direction of travel. 

(b) A combination lever attached at its lower end to a union link 
which is connected to the piston crosshead, the upper end of the 
combination lever being coupled to both the valve spindle and 
the radius rod, the latter being attached above or below the 
valve rod, depending upon the use of inside or outside 
admission valves respectively. The layout of the gear for both 
types of valves is shown in Fig. 45. Variations of this gear to 



Fig. 44 



104 



operate outside cylinders with the valve gear inside as on 
former G.W.R. locomotives, also outside valve to operate 
inside cylinders as on the later builds of former L.M.S.R. 
4-6-2 are shown in Figs. 46 and 47. Another variation is that 
used on former L.N.E.R. 3-cylinder locomotives in which the 
Walschaert valve gear for the outside cylinders operate the 
inside cylinders through a system of levers (see Fig. 48). 
The point at which the radius rod is attached to the combination 
lever becomes the fulcrum of the whole motion, and the relative 
movement of the two ends of the lever must be such that the full 
movement of the crosshead imparted to the lower end of the com- 
bination lever will give a movement to the valve spindle equivalent 
to twice the steam lap plus twice the lead (Fig. 49). 

This valve gear is readily adapted to operate with outside or 
inside cylinders and with slide valves and outside or inside admission 
piston valves. 

The arrangement of the eccentric or return crank to provide 
movement to the valve beyond that already provided by the com- 
bination lever for lap and lead steam depends on whether inside or 
outside admission valves are employed. 

With inside-admission piston valves the eccentric or return crank 
is set at 90° behind the crank. With outside-admission valves the 
eccentric or return crank is set at 90° in front of the crank. 

The expansion link, suspended at its centre by trunnions is 
oscillated an equal amount forward and backward by the eccentric 
or return crank through the medium of the eccentric rod or return 
crank rod. An expansion die block slides in the expansion link and 
is attached to a radius rod which, attached at one end connects 
with the combination lever and is attached at the other end to the 
expansion die block in the link. The raising or lowering of the 
rear end of the radius rod causes the die block to be raised or 
lowered in the link. 

Normally the bottom of the link is used for fore-gear and the top 
of the link for back-gear working, giving a direct movement for 
fore gear and an indirect movement for back gear. The method of 
reversing is shown in the diagrams of the valve gear. 

When the die block is in the centre of the expansion link for 
mid-gear position, the expansion link does not transfer any move- 
ment to the rad.us rod. Intermediate positions of the expansion 
d.e block above or below the centre of the link allow for proportional 
transfer of movement from the link to the radius rod and valve. 

The combined movements of the two sections (a) and (h) of the 
gear result in a total movement of the valve equal to twice the 



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Fig. 49 COMBINATION LEVER 

ARRANGEMENT INSIDE AND OUTSIDE 

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amount of the steam lap plus twice the port opening to steam for 
each revolution of the driving wheels. 

Rotary Cam Poppet Valve Gear 

With reciprocating valve gears of the Stephenson and Walschaert's 
types, all the valve events of admission, expansion, exhaust and 
compression are interconnected, as we have previously seen and 
the evils of early exhaust and compression are always present when 
working with early cut-offs. To some extent long lap valves allow 
for short cut-off working. 

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109 



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independent of each other and substantial decrease in back pressure 
attained with fixed valve events of exhaust and compression for all 
positions of the reversing gear. The rotary cam poppet valve systems 
of steam distribution have been designed to achieve this object and 
allow for a greater expansion of steam, with exhaust and com- 
pression periods independent of all the other valve events, thus 
avoiding wiredrawing by the rapid opening and closing of the ports. 

The following is a description of the "British Caprotti" rotary 
cam poppet valve gear: — 

Poppet-type valves, two inlet and two exhaust valves for each 
cylinder, are provided instead of the normal slide or piston valve. 
The poppet valves are driven through a form of gear which is 
totally enclosed and running in oil. 

Fig. 51 shows an arrangement of the gear drive, the rotary 
movement for operating the valves being taken from the return 
crank gearbox fitted to the driving wheel crank pins. Figs. 52 and 53 
show an arrangement where the drive is taken from a gearbox fitted 
to the leading coupled wheel axle. 

In the camboxes are the means of controlling the valve events; 
Fig. 54 shows a section through the inlet and exhaust valves and a 
pair of valves are provided at the back and front of double-beat type, 
the inlet valves being 6£ in. diameter and the exhaust valves 7 in. 
diameter. Each valve is a self-contained unit within a cage, the 
exhaust valves being nearest to the locomotive main frames. The 
valves work vertically in the cages and are pushed down to open. 

The valves are operated and guided by the valve spindles on 
the top of which are caps. The valves are forced up to their 
seatings by steam acting on the bottom extension of the valve 
spindles. This steam is used to close the valves all the time the 
regulator is open and is controlled by means of a small valve in the 
regulator head. 

When the regulator is opened, saturated steam from the regulator 
head passes through the actuating pipe to the underside of the valve 
spindle extensions. 

A drain valve in the lowest portion of the actuating pipe opens 
when steam is shut off to prevent the accumulation of water and also 
to ensure that the valves drop off their seatings immediately the 
regulator is closed, thereby providing an automatic by-pass between 
both sides of the piston. 

The Cambox 

The principal components inside the cambox are the camshaft, 
with its cams, scrolls, scroll collar, inlet and exhaust levers, swing 
beams and rollers. 




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The camshaft, which rotates at engine speed, has the two sets of 
inlet and exhaust cams loosely mounted. Two separate cams operate 
through swing beams and tappets, the front and back inlet valves and 
similarly two separate cams operate the exhaust tappets. Mounted 
on the camshaft between the two sets of inlet and exhaust cams are 
two scroll nuts which can rotate and be moved longitudinally along 
the threaded portion of the camshaft. 

The locomotive is reversed by advancing or retarding the angular 
positions of the cams relative to the camshaft. Any cut-off desired 
is obtained by angular shifting round of the inlet cams in relation 
to each other. 

Reversing Gear 

Reversing is by means of a standard-type reversing screw and 
handle on footplate movement from two arms on the intermediate 
cross-shaft being transmitted by two short reversing rods to the 
gearboxes which finally transmit the reversing motion to the 
cambox on each cylinder. 



INSTRUCTIONS TO FOOTPLATE STAFF 

Method of working engines fitted with "Caprotti" valve gear 

Two things are absolutely essential in the working of these 
engines: — 

FIRST, THE REGULATORS MUST ALWAYS BE FIRMLY CLOSED WHEN 
COASTING. 

Under these conditions all the valves will fall fully away from 
their seatings and a full by-pass effect is obtained with the gear 
in any position. There is no necessity to move the gear to find the 
best coasting position. 

Coasting with a breath of steam will cause the valves to chatter, 
which will adversely affect their efficiency. 

Secondly, when reversing from any cut-off in fore gear, it is 
necessary to wind the reversing screw right back to full back gear. 
Similarly, when reversing from any position in back gear, the 
indicator must be traversed to full forward gear position. 

The engine will not reverse if the gear is set in some intermediate 
position. 

In all other respects the Caprotti valve gear can be operated in a 
normal manner, but to obtain the best results work the engine as 
much as possible with a full open regulator. 



116 



117 



Defects on the Road 

1. Complete failure of the engine. This can be caused by fracture 
of the main driving shaft or its universal joints and couplings, or 
defects in either the axle drive or in the cross-driver gearbox under 
the smokebox. 

2. Failure of one side of the engine will arise from any defect in the 
cross-driving shafts or couplings between the bevel pinions in the 
cross-driving gearbox under the smokebox and the cambox or from 
a defect in one of the camboxes. 

3. Valves sticking and blowing through may be due to: — 

(a) Valve spindles not working freely in their guides. 

(b) Broken valves and cages or defective valve seatings. 

(c) Leakage or stoppage in actuating steam pipe which supplies 
steam from the regulator head to the underside of the 
valve spindle extensions. 

Questions and Answers 

(1) Q. What operates the valves on a locomotive? 

A. The valves are operated by a valve gear which also incor- 
porates an arrangement for regulating the valve travel and 
for reversing the engine by changing the valve's position on 
the port face in relation to the piston. 

(2) Q. Name two common types of valve gears in use. 

A. The Stephenson's link motion; Walschaert's valve gear. 

(3) Q. Describe the Stephenson's link motion. 

A. This type of motion (illustrated in Figs. 41 and 42) employs 
two eccentrics for each valve, one being used for forward 
and the other for backward running. The fore-gear eccentric 
rod being coupled to the top and the back-gear eccentric 
rod to the bottom of the curved expansion link, which is 
supported by lifting links from the reversing shaft. The 
links and forward ends of the eccentric rods can be raised 
or lowered by means of a reversing gear in the cab for regu- 
lating the cut-off and reversing. 

The expansion link contains an expansion die block, which 
is coupled to the intermediate valve rod, but on some 
locomotives having inside-admission piston valves, the drive 
from the die block is conveyed to the valve spindle through 
a rocking lever which serves to alter the direction of move- 
ment of the valve in relation to the die block. 

On ex-G.W.R. two-cylinder locomotives employing out- 






side cylinders and Stephenson valve gear the valve motion is 
transmitted from inside the frame to the outside to actuate 
the piston valve by means of a "rocking shaft" (see Fig. 42). 
This shaft does not reverse the direction of movement of 
the valve and the eccentrics are set as in the case of a valve 
operating piston valves direct. 

(4) Q. Explain briefly the working of this valve gear. 

A. The forward and backward eccentrics are each mounted in 
their correct position on the axle to drive the valve for the 
corresponding direction of running, the usual setting being 
90° in advance of the crank in the direction of travel to give 
the necessary port opening plus an angle of advance equal 
to about 16° to provide a movement to correspond with the 
lap and lead of the valve. The total advance of each eccentric 
is approximately 106° in front of the crank in the direction 
of travel. 

In operating the reversing gear the expansion link is 
raised or lowered in order to bring the expansion die block 
in line with, or closer to, the backward or forward eccentric 
rod according to the desired direction of travel and the 
cut-off required. In full gear positions the expansion link 
die block will be either at the top or the bottom of the link, 
in mid gear it will be central where it is acted upon equally 
by both eccentrics and obtains a travel which is transferred 
to the valve equal to twice (lead + steam lap). 

It is to be noted that the amount of lead given to the valve 
by the Stephenson's motion is not constant in all positions of 
the reversing gear. In mid-gear the lead is increased above 
the amount obtained in full backward or full forward gear 
(see Fig. 43). 

(5) Q. Describe an eccentric. 

A. The eccentric is a form of auxiliary crank (see Figs. 35 and 
35a) used to obtain a reciprocating or to and fro move- 
ment for the valves from the crank axle or other rotating 
part. 

It consists of a circular disc called the "sheave" which is 
securely fixed to the axle so that it will rotate with it. The 
centre of the sheave does not coincide with the centre of the 
axle, the distance between these two centres being the 
amount of eccentricity of the eccentric in the same way as 
the distance between the crank-pin centre and the axle 
centre is the "throw" of the ordinary crank. 

The eccentricity of the "sheave" causes it to describe a 



118 



circular path about the axle centre, and consequently the 
eccentric strap, which encircles the sheave and works upon 
its outer surface, is also caused to follow the same circular 
path, producing a backward and forward movement at the 
front end of the eccentric rod. 

(6) Q. Describe a return crank. 

A. The action of the return crank is similar to that of the 
eccentric sheave (Figs. 35 and 44). It is in the form of an 
auxiliary crank fitted to the main crank pin at one end and 
to the return crank rod at the other. The difference between 
the centre of the axle and centre of eccentric crank pin 
being the amount of eccentricity as shown. 

(7) Q. Give a brief description of the Walschaert's valve gear. 

A. In this type of gear (Fig. 45) the valve travel is derived from 
two separate points. Movement amounting to twice the lap 
plus twice the lead is obtained from the piston rod crosshead, 
giving a constant lead for all positions of the gear, the 
remainder of the valve travel amounting to twice the port 
opening is obtained from the return crank through the 
medium of the return crank rod, expansion link, expansion 
die block and radius rod. The two movements, added 
together at the valve spindle pin in the combination lever, 
produce the full travel of the valve with the reversing gear 
in full forward or full backward position. 

When the expansion die block is in the centre of the link it 
is in line with the link trunnion pins and consequently no 
movement will be imparted to the radius rod, the reversing 
gear being in mid-position. In this position the valve travel 
is confined to the lap and lead movement obtained from the 
crosshead drive, the ports being open to the extent of lead 
only at each end of the cylinder. 

Fore-gear drive for the valve is obtained by lowering the 
expansion die block below and backward gear by similarly 
raising it above the link centre. 

Adjustment of the valve travel is controlled from the 
reversing gear by raising or lowering the expansion die block 
in the expansion link, regulating the amount and direction of 
the movement transmitted to the valve spindle from the 
eccentric or return crank. 

(8) Q. Why is Walschaert's valve gear fitted to modern locomotives? 

A. Because it possesses a number of important advantages over 

certain other types. It is readily adapted for use with inside 






119 



or outside admission valves and for inside or outside 
cylinders. It is capable of providing a long travel valve which 
makes for better steam distribution, it only requires one 
eccentric crank per cylinder and is not complicated, it gives 
greater facility to examine all parts and is much lighter than 
other gears. 
(9) Q- What special points should the Driver bear in mind when 
working a modern engine fitted with Walschaert's valve 
gear? 
A. That the long valve travel provides the means of taking full 
advantage of the benefits of expansive working, so that the 
best results may be obtained with the regulator well opened 
and the gear pulled up as far as possible, whenever the con- 
ditions of working will permit. 

(10) Q. Are cases of damaged motion or rods common on modern 

locomotives? 
A. No, but a case may arise where a knowledge of failures and 
remedies would minimise delay to a train and perhaps save 
the cost of sending for an assisting engine. 

(11) Q. How would you deal with a broken piston rod? 

A. With this failure it is practically certain that the front cylinder 
cover and piston head will be damaged, but that the piston 
crosshead, connecting rod and valve motion remain intact. 
If this is the case all that would be necessary would be to 
disconnect the valve on that side and secure it centrally over 
the ports of the affected cylinder. 

(12) Q. How would you secure the valve central over the ports. 

A. The drive must first be disconnected from the valve spindle, 
which on the Walschaert's gear is readily done by uncoupling 
the lower end of the combination lever. Uncouple the 
eccentric rod at the expansion link foot and secure it with the 
necessary freedom clear of any obstruction — see also 
Answer 16. 

Obtain wooden rail keys and insert the necessary amount 
of packing to secure the valve spindle guide blocks centrally 
in the guides. Firmly secure the bottom end of the com- 
bination lever as far forward as possible to clear the gudgeon 
pin when running. It must be noted that this prevents any 
movement of the reversing gear without first freeing the 
combination lever. 

It would not be necessary to disconnect the motion on the 
affected side from the reversing shaft. In all cases where 



120 



engine failures require the dismantling of any detail and 
securing of other parts the engine should be moved slowly 
for the first turn to ensure that everything is clear for 
running. 

(13) Q. To disconnect a valve on the Walschaert's gear is it necessary 

to remove the whole of the motion on that side? 
A. No, it is only necessary to take down the return crank rod 
and to remove the union link which connects the crosshead 
arm to the lower end of the combination lever. The whole 
of the remaining rods may be left in position, the valve 
spindle can be secured central over the ports in the manner 
described previously. 

It is unnecessary in this case to uncouple the radius rod 
from the reversing shaft arm due to the fact that the expansion 
link will be left swinging free, so that the movement of the 
reversing shaft will not be transmitted to the valve spindle. 

(14) Q. What can be done if the radius rod breaks with the 

Walschaert's gear? 

A. Disconnect the affected valve entirely by removing the 
union link from the crosshead, centralise the valve over the 
ports and secure as previously described. Tie up the broken 
portion of the radius rod clear of all moving parts, but do 
not waste time in trying to remove them. If the engine has 
not far to run, the connecting rod may be left in position and 
the cylinder cocks left open. Lubricate the piston generously 
by working the mechanical lubricator by hand before 
starting and occasionally during the journey. 

(15) Q. What would you do if the combination lever broke? 

A. Disconnect the affected valve entirely by removal of the 
return crank rod, centralise and secure the valve as described, 
then proceed as in previous question when locomotive can be 
worked on one side to nearest Motive Power Depot. 

(16) Q. What would you do if the return crank rod broke with the 

Walschaert's valve gear? 

A. Remove the rear portion of the broken rod and tie up the 
front part clear of moving parts. Disconnect the affected 
motion from the reversing shaft and then fasten the expansion 
die block centrally in the expansion link by means of 
packing. The engine may then be worked on the remaining 
cylinders with the damaged side working on lead steam only. 
In the event of the return crank rod being fitted with ball 






121 






bearings, the return crank rod would require to be removed 
complete and, as the connecting rod big end is retained in 
position by the return crank, a special washer would be 
required to be fitted to the main crank pin to retain the 
connecting rod in position. Assistance would be required 
from a Motive Power Depot. 

If it is an outside motion affected it should be noted that 
the mechanical lubricators may be put out of action if they 
are driven from the disconnected link and they must therefore 
be worked by hand. 

(17) Q. If when running in back gear the reversing rod broke, what 

would occur? 
A. In this case the motion would creep into forward gear and 
the effect noted in the action of the locomotive. 

(18) Q. If this occurred what would you do to make the engine fit to 

proceed ? 
A. If fitted with Walschaert's gear the reversing shaft arm would 
have to be levered until the expansion die blocks were raised 
to the desired position in the links and wooden packing 
should be inserted in each link below the die block to support 
it in position. The die blocks should also be packed on the 
opposite side of the link to prevent any tendency to jump 
when running. The packing pieces should be securely tied 
in position with rope or cord to prevent their working out of 

position. 

If the engine were fitted with Stephenson's link motion it 
would be necessary to lift the links by levering the reversing 
arms upward until the die blocks are set in a suitable position 
for running backwards and then to insert wooden packing 
over each die block to support the links in the desired 
position. It would be desirable to insert packing below the 
die blocks also, to prevent any tendency of the links to jump 
when running, allowing a small vertical movement for slip 
of link. 

(19) Q. If the valve spindle were broken between the heads on an 

inside-admission piston valve, what would you do? 
A. In this case the front head would be driven forward and held 
at the forward end of the steam chest by the steam pressure, 
leaving the front port permanently open to steam; probably 
the quickest remedy in such a case would be to uncouple the 
valve spindle by removal of the union link and return crank 
rod on the Walschaert's motion and to draw the rear portion 



122 



of the valve spindle right back and secure it there in order to 
open the back port to steam also. This will place the piston 
in equilibrium with steam at equal pressure front and rear 
so that the removal of the connecting rod will not be 
necessary. 

With the Stephenson link motion it will be necessary to 
uncouple the valve spindle by removing the valve link from 
the rocking or rock shaft. 

(20) Q. How would you make the engine fit to travel under its own 
power with a valve spindle broken behind the valve? 
A. In this case the valve would come to rest in its forward 
position, so that if it were of the outside-admission type the 
back port would be left open to steam, and if it were an inside- 
admission valve the front port would be left open. It would 
be necessary, therefore, to remove the connecting rod and 
place the piston at the end of the cylinder remote from the 
open steam port and to secure the piston rod in this position 
by packing with wood ropes to the slide bar. The back 
portion of the valve spindle should be pushed against the 
front portion and wedged in that position to prevent the 
valve on the port face from moving, also the valve gear, of 
whatever type, would have to be disconnected from the 
valve spindle to ensure that no movement would be imparted 
to the defective valve. 

Note: The former G.W.R. four-cylinder locomotives are 
fitted with Walschaert's valve gear between the frames and 
require to be dealt with in a slightly different manner. 

(21) Q. If one of the outside cylinder pistons became defective, 

would it be possible to work on three cylinders? 
A. Yes. Disconnect the outside valve at the knuckle joint of the 
defective side, place piston valve central and secure the 
adjusting link to prevent it striking the valve spindle. 

(22) Q. How would you uncouple one of the inside Walschaert's 

valve gears to make the engine fit to travel ? 
A. Take down the combination lever and anchor (guiding) link 
and place reversing gear in mid-gear. There are three bridle 
rods to these engines, one from the screw to the reversing 
shaft and one on each side from the reversing shaft arms to 
the valve gear. To complete the uncoupling it would be 
necessary to take down the inside bridle rod on the other 
faulty side, then using the same pin, couple the auxiliary shaft 






123 






arm to the emergency bracket fixed on the inside of the 
framing. 

(23) Q. If, when running,your locomotive suddenlylost twobeatsand 

commenced to ride somewhat roughly, but developed no 
blow from the chimney, what would you conclude had gone 
wrong and what would be your procedure under such 
circumstances? 
A. I should conclude that one valve had become uncoupled due 
to broken valve spindle, eccentric rod or other main portion 
of the motion. I should at once ease the regulator, open the 
cylinder cocks and keeping the reversing gear as near to 
mid-gear as possible (providing the trouble showed no signs 
of becoming worse) endeavour to bring my train under 
protection of fixed signals before stopping. 

(24) Q. How would you deal with a broken back-gear eccentric rod 

or strap with Stephenson's link motion ? 
A. If working in fore gear the quickest procedure would be to 
remove back-gear eccentric rod and strap, drop the reverse 
into fore gear, secure the link so that the locomotive cannot 
be reversed and proceed. 

Where the lifting link is secured to centre of expansion 
link, the bottom of the expansion link should be secured to 
the motion plate to prevent it striking. If necessary to run 
backwards, the forward eccentric rod and strap will require 
to be removed, the valve disconnected and secured in mid- 
position and the locomotive worked on one side. 

Other Running Gear Failures 

(25) Q. In the case of a broken or bent side rod, what should be 

done? 
A. Take down the broken or bent rod or section of rod and the 
corresponding rod or section of rod on other side of the 
locomotive. If the front section of six-coupled locomotive's 
coupling rods became broken or bent all side rods would 
have to be taken off; similarly, if the middle section of an 
eight-coupled locomotive's side rod broke, all coupling rods 
would have to be dismantled. 

(26) Q. For what breakdown is it necessary to take down the 

connecting rod and/or side rods? 
A. Broken connecting rod, big- or little-end straps, main crank 
pin, crosshead guide or a defective valve which cannot be 
closed. 



124 



The side rods must be taken down on both sides for 
broken main crank pin or broken side rod pin. 

(27) Q. What should be done if a bearing spring dropped, spring 
badly broken or a broken spring hanger? 
A. Bring the train under such control in order to proceed 
cautiously to the protection of fixed signals where an 
examination can be made. 

If the leading spring is broken or lost and the engine is a 
considerable distance from a Motive Power Depot, as 
quickly as possible raise the locomotive by running' the 
second pair of wheels, on the same side, on to a suitable 
packing, such as a steel chisel, coal pick or fishplate placed 
on the rail, so that the leading end of the engine will be lifted 
high enough to enable a suitable piece of packing to be 
inserted on the top of the axlebox affected, then slowly move 
off the packing on the rail and proceed at reduced speed 
until a fresh locomotive can be obtained. By this procedure 
the weight is transmitted direct to the axlebox instead of 
through the spring. In the event of driving, or any of the 
other bearing, springs being affected, run the next pair of 
wheels on to packing on the rail and proceed as for the 
leading wheel spring. 

(28) Q. When an engine or tender has been re-railed after derailment, 

what should the Driver be very careful about? 
A. He should see that the springs, pins and hangers are correct 
and that no packing has been left on the axleboxes or under- 
keeps. He should also have the wheels gauged. 

The tender, pony truck or bogie brasses must be examined 
to see that they are in their proper position and the packing 
or oil pads are in position. 

(29) Q. If you discovered that your locomotive had a hot big end and 

that there was a risk of the metal being fused, how would 
you handle the engine? 

A. I should keep a breath of steam on at all times and would 
even bring the train to rest with the regulator open slightly. 
The cut-off should be maintained as long as possible in 
order to maintain a more even pressure on the journal and 
keep the brass in contact with it. 

(30) Q. Why should you handle the locomotive in this way? 

A. Because, if the metal did fuse in the big-end brasses, the 
excessive knock might break up the bearing if the steam were 






125 



shut off. In this event it is possible that one or other of the 
cylinder covers may be fractured. By keeping a breath of 
steam on, however, the moving parts are cushioned and 
damage to the cylinder and piston may possibly be averted. 

(31) Q. What are some causes for knocks? 

A. Driving or coupled wheel axleboxes worn on the bearing or 
between the horns, worn connecting rod and side rod 
bushes, worn crossheads, piston rod loose in crosshead, 
loose piston head, fractured frame or obstruction in the 
cylinder. 

(32) Q. How may a knock be usually located? 

A. Place locomotive on top or bottom quarter on side to be 
tested. Reverse from forward to back gear with the regulator 
open, noting the movement of the axleboxes, connecting rod 
and side rod bushes, crosshead and piston rod. Ensure the 
cylinder is not working loose on the frame. 

(33) Q. What point do you regard as of special importance in 

connection with sand gear ? 
A. That the sand boxes on each side of the locomotive are filled 
and that the ends of the sand pipe nozzle are properly 
adjusted to deliver the sand between the tread of the wheel 
and the face of the rail. Both sanders must work simul- 
taneously, for if only one sander is working there is a grave 
risk of broken coupling rods and crank pins. 

(34) Q. Would you apply sand to the rail when the locomotive is 

slipping and the regulator open? 
A. No. To avoid sudden strains on the motion the regulator 
must be closed and slipping have ceased before applying the 
sand. 






126 



SECTION 7 



LUBRICATION 



Lubricating oil is used to keep the bearing surfaces apart and 
permit easy running and reduced wear and tear. This is brought 
about by forming a film or layer of oil between the bearing and 
shaft or between the sliding surfaces to prevent metallic contact. 
When oil is allowed to spread over a clean metallic surface it forms 
a thin film of great stability. This film may be only 100,000th of an 
inch in thickness, but it adheres strongly to the metal and two such 
films, one on each surface, slide over each other and protect the 
metals from contact and wear. "Oiliness" is the property of a 
liquid which enables it to form a powerful lubricating film when 
spread as a layer between the two surfaces. 

When a locomotive is working, the chief kinds of motion are: — 

(1) Rotating — as in axle and big-end bearings. 

(2) Sliding — as in pistons, crossheads and valves. 

(3) Rocking — as in parts of a valve gear and little-end bearings. 
In the first of these types it is easier to maintain a fluid film as the 

rotation assists the distribution of the oil, but in the other two cases 
it is more difficult. For example, a piston slows down and stops at 
the end of each stroke and reverses direction; again, a small end has 
only a limited amount of movement. Under these conditions, which 
are unfavourable to the maintenance of a fluid film, we depend upon 
the "oiliness" of the lubricant to prevent metallic contact. 

Methods of Lubrication 

A. Hand Lubrication 

Example: Hand brake gear, firedoor slides, screw couplings, etc. 
Description: Oil is applied by a hand oil feeder daily or as 
required. 

B. Pad Lubrication {Worsted) 

Example: Chiefly used in underkeeps of axleboxes. 
Description: The worsted pad is supplied with oil by tail 

feeders attached to the pad and dipping into a bath of oil in 

the underkeeps. 

C. Syphon Lubrication 

Example: Axleboxes, slide bars, horn cheeks, etc. 
Description: The oil is fed to the bearing or surface from an 
oil box by means of a worsted tail trimming (see Fig. 55). 



127 










Fig. 55 WORSTED TRIMMINGS 

Details of Preparation 



D. Mechanical Lubrication 

Example: Axleboxes, pistons, valves and cylinders, etc. 
Description: Lubrication is effected by means of a mechanical 
pump (see Figs. 56 and 57). 

E. Hydrostatic Sight Feed Lubrication 
Example: Valves, pistons and cylinders. 

Description: Lubricators of this type work on the principle of 
the displacement of oil by means of condensed steam (see 
Fig. 58). 

F. A tombed Lubrication 

Example: Valves, pistons and cylinders. 

Description: With both mechanical and sight feed lubricators 
the oil is atomised with steam and sprayed through a choke 



128 



before it reaches the cylinders. In some systems of mechanical 
lubrication, steam to the atomisers is controlled automatically 
from the cylinder cock gear (see Fig. 59). 

G. Rest He tor Plug Lubrication 

Example: Big ends and side rod bushes. 

Description: On revolving parts, the oil supply tube in the oil 
well is fitted with either a worsted trimming, a screwed metal 
restrictor or a needle. These devices regulate the quantity of 
oil passing down the oil tube, the oil being thrown to the top 
of the oil tube by the movement of the part concerned (see 
Fig. 60). 

H. Fountain-type Lubrication 

Example: Axleboxes on a small number of classes of 

locomotives. 
Description: This lubricator feeds oil by gravity to the axle- 
boxes and consists of an airtight oil reservoir which supplies 
oil to a feed chamber through a main shut-off valve. The 
level of the air in the chamber controls the admission of air 
to the reservoir, thereby regulating the delivery of oil from it. 
Oil leaves the feed chambers through drip nozzles, the flow 
being regulated by feed needles and passes through sight feed 
glasses into the oil pipes, thence by gravity to the axleboxes 
(see Fig. 61). 

I. Grease Lubrication 

Example: Ball and roller bearings, return crank, motion parts, 
brake gearings, water pick-up gearings, pony trucks, reversing 
screw, etc. 

Description: Grease nipples are screwed into each lubricating 
point, being sealed with a spring-loaded valve to prevent dirt 
getting into the hole. A grease gun is used to force lubricant 
through the nipples to the point of lubrication. 

Lubrication of Axleboxes 

Locomotive axleboxes can be divided into two types, viz. (a) dead 
load bearings as fitted to bogie, pony truck, bissel trucks and tenders; 
(b) dead load-power bearings, as on the driving and coupled wheels, 
which in addition to taking the dead weight are also called upon to 
transmit a considerable proportion of the piston thrust to the 
locomotive frames to form the tractive force. 

On modern locomotives the former type of bearing depends 
entirely on oil supplied by the underfeed keep pad, and care must be 



129 



taken during preparation to check the underkeep oil level. 

With coupled wheels, although oil can be supplied to the bearing 
by mechanical lubricator or trimming feed, the method of applying 
the oil to the actual bearing surface varies, but the following are in 
common use: — 

(1) By a straight oil groove cut on crown of bearing. 

(2) By oval groove on crown of bearing. 

(3) By straight oil grooves at 45° on each side of the vertical 
centre line of bearing. 

(4) By oil holes on horizontal centre line of bearing. 

(5) Plain whitemetal bearing with underfeed keep lubrication 
(latest practice). 

A number of locomotives are being fitted with roller bearings on 
all axles. The advantages of these are lower lubricating costs and 
lower resistance when starting from rest. 

Where mechanical lubrication is employed a spring-loaded back- 
pressure valve is fitted on the axlebox, whose function is to keep the 
oil supply pipe full whilst the locomotive is standing, so that the oil 
supply commences immediately the locomotive moves. 

With bearings as described in item (5) the oil supply is mechanically 
fed to the underkeep. 

Mechanical Lubricators 

The Silvertown mechanical lubricator consists of a cast-iron box 
into which is fitted a number of independent oil pumps, all of which 
are operated simultaneously. The box itself forms an oil container 
and is fitted with a hinged lid for the purpose of replenishing the 
oil, which is filtered through a fine-mesh sieve (Fig. 56). 

The supply pumps are double acting, oil is delivered on both the 
up and down movements of the pump plunger, giving a continuous 
oil supply. The lubricator is driven from some convenient point on 
the motion through a ratchet wheel which drives the shaft in one 
direction. On each end of the shaft is a cam working in slots in the 
driving frame, the latter being so arranged to slide vertically in 
guides at each end of the lubricating box. When the driving shaft 
revolves a reciprocating motion is given to the frame which is 
connected to the pump plunger by means of thimbles. 

The action of the pump is as follows: — 

On the upward movement of the plunger, oil is drawn via a small 
sieve past a ball valve, thus filling the space below the plunger. 
During the downward movement of the plunger the ball valve is held 
on its seat and the oil is forced up the passage past the ball valve, 
half of the oil filling the cavity on the top of the plunger and the 



130 



Fig. 56 SILVERTOWN MECHANICAL LUBRICATOR 








131 



A. CAVITY 

B. PASSAGE 

C. SUPPLY PUMPS 

D. PUMP PLUNGER 

E. PACKING 

F. BALL VALVE 

G. BALL VALVE 

H. DRIVING FRAME 
J. SHAFT 



K. SMALL SIEVE 

L. FINE-MESH SIEVE 

M. WARMING PIPE 

N. DRAIN PLUG 

O. DRIVING SHAFT HANDLE 

P. THIMBLES 

Q. DRIVING WHEEL 

R. FIXED WHEEL PLATE 

S. PAWL 



remaining oil being forced past the ball valve into the lubricating 
system. It will be seen that on the upward movement, in addition 
to the oil being drawn into the lower passages of the pump, the oil 
remaining in the cavity is also forced past the ball valve, during 
which operation the ball valve is held on its seat. Special packing is 
provided to prevent leakage of oil from the top side of the plunger. 

The rotary movement of the shaft is obtained by six spring-loaded 
pawls fitted to the outer case of the ratchet box and engaging in teeth 
on the outside edge of the driving wheel which is keyed to the main 
shaft, so that when the case is moving in one direction the driving 
wheel is rotated, but in the return direction is held in position by 
means of the six retaining pawls provided in the fixed wheel plate. 

Each pump feeds approximately 2 oz. per 1 00 miles. 

On the opposite end of the driving shaft a handle is fitted which 
can be turned by hand to operate the pump independent of the action 
of the locomotive. This handle should be rotated a few times before 
leaving the shed. 

These lubricators can be used to supply oil to the axleboxes or 
to the cylinders. When used for the latter purpose, as a thick oil 
is used for cylinder lubrication, it is necessary to provide means for 
preventing the oil from congealing in cold weather and this is 
achieved by fitting a warming pipe through which a supply of steam 
is passed. This supply of steam can be cut off during the summer 
weather. When necessary the oil can be drained from the lubricator 
through a drain plug. 

Hydrostatic Displacement Lubricator 

The principle of the hydrostatic displacement lubricator is the 
utilisation of condensed steam from the condenser coil, which on 
entering the oil reservoir displaces the oil causing it to overflow into 
the feed passages. Oil is controlled by the oil-regulating valve and, 
after passing this point, it rises through the water in the sight glass 
into a delivery chamber from which it is carried by steam through 
the lubricator pipes to the choke which is inserted in the lubricator 
pipe near the delivery point on the main steam pipes. The choke 
plug gives a constant resistance to the lubricator and so prevents 
the feed being affected by variations of pressure in the steam chest. 

On the former G.W.R. locomotives the oil is atomised by passing 
through a small orifice from the delivery chamber. 

The usual rate of feed should be two to three drops per feed per 
minute, according to the class of work performed. 

A Detroit hydrostatic lubricator is shown in Fig. 58. This is a 
four-feed lubricator and the working instructions are as follows: — 

To fill: Turn oil control valve to closed position. Shut water valve 



132 



and steam valve, open the drain plug in order to empty water 
from oil reservoir and release pressure, next remove filling plug 
slowly. (The reason for removing this plug slowly is to allow 
any pressure which may have built up in the reservoir to escape 
past the threads.) Close the drain plug and fill reservoir with 
clean oil; if there is insufficient oil on hand use water to fill 
reservoir completely. (Some lubricators of this type are not 
fitted with oil control valve; in this case when filling close all 
feed regulating valves.) 

To start: Fully open the steam valve and allow three or four 
minutes to elapse in which to fill the condenser and sight feed 
glasses with water, then fully open water valve, turn oil control 
valve to "open" position and regulate the oil feed valves. 

To shut down lubricator: For short stops shut down oil control 
valve only; for long stops close oil control valve, water valve, 
and lastly steam valve. 

Note: Always start the lubricator ten minutes before leaving 
the shed. 



Fig. 57 WAKEFIELD MECHANICAL LUBRICATOR 

No. 7 Pattern 

HOW THE LUBRICATOR WORKS 

When the pump plunger D and sleeve valve E are at the outer end of the 
stroke, oil flows into the pump barrel C through the ports F. As soon as the 
ports F are covered by the plunger and sleeve valve on the return stroke, the 
oil in the pump barrel is forced away under pressure to the outlets K. If the oil 
regulating plug G is screwed right down, the pumps are working at their full 
capacity. One full turn outwards of the oil regulating plug G decreased the oil 
pumped by one-fifth as follows: — 

Plug G screwed right down = full feed. 

Plug G screwed one turn out = four-fifths feed 
Plug G screwed two turns out = three-fifths feed 
Plug G screwed three turns out = two-fifths feed 
Plug G screwed four turns out = one-fifth feed 
Plug G screwed five turns out = feed cut off 

TO OPERATE 

When starting the Lubricator for the first time when newly fitted — 

(1) See that each of the oil regulating plugs G is screwed right down. 

(2) Fill the oil reservoir, taking care to pass the oil through the strainer. 

(3) Open the oil-test plug on the combined check valve and oil-test plug. 
(A) Work the Lubricator by turning the flushing wheel until the oil is seen 

at the oil-test plug. 
(5) Close the oil-test plug and work the Lubricator a few more times to 
make sure that the oil-delivery pipes are quite full. 
The above operations are essential when the lubrication is first fitted up. 
The lubrication system is then in working order. 

It is advisable before leaving the shed, with the engine going into traffic, to 



133 



examine the test plugs and make sure the oil is there by giving the flushing 
wheel a few turns. 

The level of the oil in the reservoir must never be allowed to fall below the 
ports F in the pump barrels or no oil will be delivered. 

The oil MUST pass through the sieve. It is advantageous to WARM the cylinder 
oil before filling the lubricator. 




SECTIONAL ELEVATION 



A. OIL RESERVOIR 

B. WIRE GAUZE STRAINER 

C. PUMP BARREL 

D. PUMP PLUNGER 

E. SLEEVE VALVE 

F. OIL PORTS 

G. OIL REGULATING PLUG 

H. OIL REGULATING LOCKING PEG 

J. NON-RETURN VALVE 



K. OIL OUTLETS 

L. DRIVING ECCENTRIC SHAFT 

M. OIL WARMING PIPE 

N. DRIVING ARM 

O. RATCHET DRIVE AND GEAR CASE 

P. FIXING LUGS 

Q. FLY BOLT TO SECURE LID 

R. FLUSHING WHEEL 

S. DRAIN PLUG 



NOTE. — No. 7 (a) pattern operates in a similar manner to the above, but the oil outlets K lead 
out from the sides of the oil reservoir, level with the centre of the driving eccentric shaft L. 



134 



135 












z 


* 








o 


<z 


u 


5< 


z 


3° 








z 



h 



CD 

D 

-i 

cc 

UJ 

Z 
O 

H 
< 
u. 


H 
Z 

UJ 

Z 

UJ 

O 

z 
< 

cc 
cc 

< 



06 



Fig. 58 






Fig. 59 



136 



Fig. 60 CONNECTING ROD LUBRICATION 



SYPHON PLUG 
SYPHON CORK_VoiL CUP 



BUSH 




RESTRICTOR 



OUTSIDE BIG END 



OILING WASHER 



FOUNTAIN-TYPE AXLEBOX LUBRICATOR 



INSTRUCTIONS FOR OPERATING 

TO FILL Set handle "P" in "OFF" position. 

Remove filling plug "B" and fill reservoir with clean oil. 

Replace filling plug "B" making sure that it is screwed down and air tight. 

TO OPERATE Examine needles "J" to see that they are clean, and that no foreign matter is 

accumulated around or in the nipples "V." 

Then replace needles "J" and move handle "P" to "ON" position. 

SPECIAL NOTE Handle "P" has two positions. "ON" and "OFF." It does not regulate the oil 
feed. Feed regulation is obtained by varying the size of needle "J." 
NO OIL MUST BE POURED INTO CHAMBER "F." 
Lid on chamber "F" is for inspection purposes only. 

Move handle "P" into "OFF" position when running into terminal stations, or during any lengthy 
stoppage. 

Do not move handle "P" into the "ON" position until the steam regulator is again opened. The small 
quantity of oil accumulating in each chamber "G" from feed chamber "F" flows quickly down the oil 
pipes to the journals immediately the Lubricator is set to work again. 

When shunting, operate Lubricator at intervals sufficient to maintain an oil film on the journals. 
Should an Axle-box heat, remove needle "J" of the Axle-box feed concerned to temporarily increase 
the oil delivery until conditions improve, then replace needle "J" or fit a smaller size needle. 

TO DETECT STOPPAGE IN PIPE LINE Should oil flood sight glass, it indicates that the feed 

pipe is choked between the Lubricator and the air inlet in the pipe line. 

If oil appears at the air inlet in the pipe line it denotes an obstruction in the pipe between the air 

inlet and Axle-box. 

Air inlets should be periodically examined and kept free from dirt. 



137 



HOW IT FUNCTIONS When handle "P"' is set in the "ON" position, oil from the reservoir 

"A" passes through main shut-off valve "C" and along passage "D" into feed chamber "F," where it 

rises to a level just above top of outlet passage "D" and is fed through the nozzle "L" in drops 

regulated by the needle "J" fitted in the nipple "V." 

As soon as the oil level in chamber "F" drops below top of passage "D," air enters the reservoir 

"A" through the air tube "T." destroys the partial vacuum, permits the oil to flow through until 

it again rises to a level above the top of passage "D" and cuts off the air. 

This cycle of operations is repeated the whole time the handle "P" is in the "ON" position. 

When handle *'P" is in the "OFF" position, the main shut-off valve "C" and shut-off valves "K"are 

closed, and oil in the chamber "F" continues to feed to each auxiliary chamber "G" until the oil 

level in chamber "F" falls to the level of the top of the nipple "V." 

Immediately handle "P" is set in the "ON" position the oil accumulated in each chamber "G" 

quickly flows down the pipes to the journals, while the cycle of operations between the reservoir 

"A" and chamber "F" has allowed the level in chamber "F" to rise and feed oil past the needle "J." 

The air tube "T" regulates the expansion or contraction, due to variation of temperature in reservoir 

"A." 

By strictly observing the above instructions, an appreciable economy in oil consumption will be 

effected. 



SECTION 


SECTION 


SECTION 


THROUGH 


THROUGH 


THROUGH 


Y Y 


Z Z' 


X X 



AIR INLET 




OIL DELIVERY 
TO AXLE-BOX 



A. OIL RESERVOIR 
B FILLING PLUG 

C. MAIN OIL SHUT-OFF VALVE 

D. OIL OUTLET FROM RESERVOIR 
TO FEED CHAMBERS 

E. BAFFLE 

F. OIL FEED CHAMBER 

G. AUXILIARY OIL CHAMBER 
H. AIR VENT 

J. FEED REGULATING NEEDLE 
K SHUT-OFF VALVE 



OUTSIDE VIEW 



L DRIP NOZZLE 

M SIGHT FEED GLASS 

N SIGHT FEEO FITTING 

O. OIL OUTLET 

P. OPERATING HANDLE 

O DRAIN PLUGS 

R OIL LEVEL GAUGE GLASS 

S. FIXING LUG 

T AIR INSET TUBE 

U WIRE GAUGE STRAINER 

V. FEED NIPPLE 



Fig. 61 FOUNTAIN-TYPE AXLEBOX LUBRICATOR 



138 






Roller Bearings 

With a view to obtaining economies brought about by more 
trouble-free running and increased mileages between shop repairs, 
roller bearings are being fitted to locomotives in increasing numbers, 
especially to axlebox bearings. 

Roller-bearing Axleboxes 

Fig. 62 illustrates typical inside and outside journal roller- 
bearing axleboxes. The bearings used in these axleboxes consist of 
four main components as follows: — 

1. cone (inner race). The cone is pressed on the axle and there- 
fore rotates with the axle. 

2. cup (outer race). The cup is loosely mounted in the axlebox 
body, but does not rotate. 

3. rollers. The rollers transmit the journal load of the vehicle 
from the outer to the inner race and roll along the track on the 
cone. 

4. cage. The cage ensures that the rollers are correctly spaced. 

A. This illustrates an axlebox for outside journals as used on 
certain trailing truck and tender axles. It includes a double bearing, 
which in effect is two single sets of rollers running on two single 
cones. 

B. This illustrates an axlebox for outside journals as used on 
certain tender axles. It includes a double bearing, which, in effect, 
is two single sets of rollers running on a double cone. 

C. This illustrates a cast-steel axlebox as used for inside journals 
and is known as a "cannon box". It includes two single bearings, 
one per journal, mounted in a tubular steel housing which 
entirely surrounds the axle throughout its length between the wheel 
bosses. Earlier designs of cannon boxes were made in two halves 
bolted together, but the latest type consists of a solid one-piece 
tubular casting. 

The construction of these bearings, where tapered rollers run on 
the tapered working surfaces of a cone and cup, makes it equally 
suitable for handling loads at right-angles to the axle (radial loads 
such as spring loads, brake loads and piston loads) and thrust 
loads set up along the axle when the vehicle is negotiating curves in 
the track. Only the upper rollers carry radial load, whereas all the 
rollers carry thrust load. 

The bearings are lubricated by oil which is automatically circu- 
lated in the axlebox by the action of the tapered rollers. Oil level, 
which is checked with a gauge, should be topped up with the correct 
grade. of oil when the level is down to the lower mark on the gauge. 






139 






SPRING SEAT 



ENCLOSURE 
GREASE FEED 




OIL FILLER 
PLUG 



OIL DRAIN 
PLUG 



HORNGUIDE 

HORNGUIDE LUG 

CONE SPACER 

CUP SPACER 



SPRING SEAT 



BACK COVER 




HORNGUIDE 
HORNGUIDE LUG 



CUP 



SPRING HANGER 
PIN HOLE 



WHEEL SEAT 



CONDENSING VENT 

OIL DRAIN PLUG 

Cannon Box 



HORNGUIDE LUG 
HORNGUIDE 



Fig. 62 TYPES OF ROLLER-BEARING AXLEBOXES 






140 



This work is carried out by artisan staff, but Enginemen should note 
that the entry of dirt or water into the axlebox would prove extremely 
harmful to the bearings. 

A condensing vent is cast in the inspection cover of axleboxes 
(A and B), whilst a condensing vent pipe is fitted to cannon boxes 
(C). This vent allows the axlebox to "breathe" when the air inside 
the axlebox expands and contracts. 

With a roller bearing the loads are handled on rolling surfaces 
similar to a wheel rolling on a rail, not on a sliding surface as when 
a weight is dragged along a road. This is the important difference 
between a roller bearing and a plain bearing. The friction in the 
bearing is very small and therefore the tractive resistance or 
resistance to free running is very low. At starting some of the 
power developed by a locomotive is absorbed as friction in a plain 
bearing axlebox and is lost. This loss is almost eliminated on a 
roller-bearing-equipped locomotive; it can therefore develop more 
useful tractive effort. 

Atomiser Lubrication 

From the cylinder mechanical lubricator oil is forced by the pump 
to the atomiser (Fig. 59), where it is atomised by means of a steam 
jet and then passed to the steam chest. The steam for atomisers is 
taken from the manifold. The steam pipe also includes a valve 
coupled to the cylinder cock gear, which is shut when the cylinder 
cocks are open. For this reason it is imperative that the cylinder 
cocks be left open whilst the locomotive is standing. 




141 



forming a plug, which should be a comfortable fit in the 
syphon tube, and when in position the top of the plug should 
reach a little below the top of the syphon tube to form a well 
to accommodate a small quantity of oil above the trimming. 
The extreme length of the plug should be shorter than the 
length of the tube to obviate it touching the bearing. 

Although, within certain limits, the amount of oil fed will 
vary according to the number of strands in the plug, care 
must be taken to adhere to the standard as too many strands 
may restrict the passage of oil to the bearing. 

Tail trimmings are used for non-rotating parts such as 
axleboxes, piston and valve spindle glands, etc., and they are 
made of the same material as plug trimmings, the strands 
being left of sufficient length to fit the syphon tube and hang 
into the oil box to syphon the oil from the oil chamber to the 
syphon tube when in position, the oil falling from the 
trimming in the tube by gravity to the point to be lubricated. 
The number of strands, within certain limits, will increase 
the supply of oil with the increase in strands, provided they 
are kept clean. Tail trimmings should be removed from the 
syphon tube, when not required, to avoid waste of oil. 

Other trimmings in the form of a pad are used for 
expansion die blocks, expansion link pins and side blocks; 
these pads being saturated with oil each time the locomotive 
is prepared, the oil lubricating the part slowly during the 
time of working. 



Questions and Answers 

(1) Q. Why is the cylinder Oil issued for the piston and valves of 

non-superheated engines different from that issued for 
superheated engines? 

A. The oil used in the latter for lubricating the valves and pistons 
must be able to retain its lubricating properties at higher 
temperatures than is necessary with saturated steam. 

(2) Q. Describe the use of worsted trimmings. 

A. A plug trimming is used to feed rotating and oscillating parts 
having sufficient motion to splash the oil over the end of the 
syphon tube when the locomotive is in motion. Big ends, 
outside rods, eccentrics and in small ends of older types of 
locomotives. 

A plug trimming is made by wrapping several strands of 
worsted lengthwise over a length of twisted wire and 



142 



SECTION 8 
BRAKES 

The function of the brake is to absorb by friction the momentum 
of the train; in other words, the energy stored in the moving train 
is converted to heat at the brake blocks when the brakes are applied. 

In the working of freight and mineral trains not made up of 
power-braked vehicles, the braking of the train is dependent upon 
the brakes of the locomotive together with the screw hand brake on 
the guard's brake van, supplemented on certain sections of the 
line, where there are severe gradients, by stopping the train and 
applying the hand brake on a number of vehicles before descending 
the incline. 

For the working of passenger trains it is necessary, in order to 
comply with an Act of Parliament passed in 1889, that (1) the brake 
on the train should be continuous and capable of being applied to 
every vehicle of the train; (2) be instantaneous in action and capable 
of being applied by Driver and/or Guard; (3) be self-applying in 
the event of the train becoming divided. 

These conditions are fulfilled by the two main braking systems in 
common use to-day, namely, the "automatic vacuum brake" and 
the "Westinghouse automatic air brake". 

The "automatic vacuum brake" is used almost exclusively on 
steam-hauled trains in this country and makes use of the atmospheric 
pressure. 

The system consists essentially of an exhausting device on the 
engine known as the vacuum ejector, which has a large ejector used 
to create quickly the regulation amount of vacuum in the train 
pipe, connections and reservoir and both sides of the brake cylinder 
pistons throughout the train, together with a small ejector to 
maintain the vacuum. Some locomotives are fitted with a vacuum 
pump which serves a similar purpose to the small ejector. 

The pressure of the atmosphere is approximately 15 lb. per sq. in. 
and the vacuum is measured in inches of mercury. A perfect vacuum 
corresponds to approximately 30 in. of mercury, i.e. lb. per sq. in. 
pressure. This varies slightly with the atmospheric pressure as 
measured by a barometer. Therefore, it will be evident that each 2 in. 
of vacuum represents approximately 1 lb. per sq. in. of atmospheric 
pressure. 

The regulation vacuum for working the brakes is 21 in. on all 
Regions except the former G.W.R., where the amount is 25 in. 



143 



To apply the brakes, air is admitted to the train pipe and train 
pipe connections so that the vacuum on the lower side of each 
brake piston is partially or completely destroyed. The vacuum on 
the reservoir and upper sides of the brake pistons, however, is 
retained, being sealed off by a ball valve. 

In a normal application of the brakes the Driver can admit the 
desired amount of air to the train pipe by way of the ports in the 
Driver's application valve, the quantity of air admitted regulating 
the power of the application. Full power is utilised when the vacuum 
in the train pipe is totally destroyed. 

Some arrangements of the automatic vacuum brake are worked 
in conjunction with steam brakes on the engine and tender or in 
conjunction with the steam brake on the engine only and vacuum 
brake on the tender. 

The arrangement which has been adopted on B.R. standard 
steam locomotives is shown in Fig. 63. In this arrangement steam 
brakes are fitted to both engine and tender, the combined ejector 
(Fig. 64) is separate from the Driver's brake application valve and 
is placed alongside the left-hand side of the boiler outside the cab. 
The body contains two ejectors, a large ejector and a small ejector, 
the action of the large and small ejectors is similar, the difference 
being that the large ejector uses more steam and thus is capable of 
creating a vacuum more quickly and therefore is for use when 
standing or when a quick release of the brake is essential. The small 
ejector is provided for maintaining the vacuum throughout the 
train and for overcoming the effect of leakage of air into the vacuum 
system due to faulty joints at the pipe connections, etc.. on the train. 
Each ejector is fitted with a non-return valve. These two valves, 
together with the non-return valve and drain connection (Fig. 63), 
provide an air lock so as to prevent smokebox gases being drawn 
back through the ejector exhaust. Each ejector works in the 
following manner: — 

Steam passing through the steam cone (Fig. 64) at great velocity 
is discharged into the ejector air cone where it comes into frictional 
contact with the air, the steam and air being exhausted through the 
ejector exhaust pipe and up the engine chimney via the smokebox 
elbow. 

In consequence of this action a partial vacuum is created and 
any air in the train pipe and connections, in its endeavour to 
destroy the vacuum created, lifts the non-return valves and finds 
its way to the ejector where it is discharged together with the steam 
through the ejector exhaust, thus a vacuum in the train pipe and 
connections is created. 



144 




Fig. 63 



145 




LARGE EJECTOR 
AIR CONE 



STEAM CONE 



SECT/ON DD 



SECTION &B 



Fig. 64 S.S.J. EJECTOR 



Under each ejector, ball drain valves are provided; whilst the 
ejectors are in use the ball is forced to its seating, preventing air 
entering; when the steam supply is shut off, the ball falls away from 
the seating and allows any condensation to drain away. A ball 
valve is provided so that in the event of leakage taking place in 
either of the non-return valves, the ball valve will open to the 
atmosphere and smokebox gases will not be drawn back through 
the ejectors when they shut off, but the vacuum maintained in the 
train pipe. 

Driver's brake application valve is shown in Fig. 65 and is designed 
to admit air into the train pipe so as to reduce or destroy the vacuum. 
It has only two handle positions, "off" and "on". 

Vacuum-operated graduable steam brake valve. This arrangement 
is shown in Fig. 66 and is designed to admit steam to the steam 
brake cylinders as the train pipe vacuum is reduced or destroyed 
and to release the steam from the steam brake cylinders as the train 
pipe vacuum is restored; in action the brake is applied on the engine 
and tender slightly later and released slightly earlier than the vacuum 



146 



APPLICATION HANDLE 



c 



LOCATION PLUNGER 

TOP COVER 

BOTTOM CASTING 



DISC VALVE 




Fig. 65 



DRIVER'S BRAKE APPLICATION VALVE 

B.R. Standard Locomotive 



brake on the train in order to minimise bunching of the carriages 
and strain on the engine and tender draw-gear; moreover, the 
pressure of steam in the steam brake cylinder is proportional to the 
amount by which the vacuum in the train pipe is reduced. 

Vacuum relief valve. This is provided to prevent the regulation 
vacuum being exceeded (see Fig. 63). It consists of a spring-loaded 
valve which lifts and allows air into the train pipe if the ejectors 
create more than 2 1 in. of vacuum (25 in. in the case of the former 
G.W.R.). 

Operation. The operation of brake arrangement as fitted to 
B.R. standard locomotives (see Fig. 63) is as follows: when in the 






147 



normal running position the train pipe will be registering 21 in. of 
vacuum, which will be maintained at this amount by the small 
ejector. Any over-creation which the small ejector might manage, 
if not satisfactorily adjusted, will be taken care of by the vacuum 
relief valve. There will be the normal train pipe vacuum below the 
vacuum cylinder piston (Fig. 66) due to the direct connection of the 



,rm 



TO VACUUM 
CHAMBER AND 
RELEASE VALVE 




TO AND FROM 

STEAM BRAKE 

CYLINDER 



SPRING 



TO 

VACUUM BRAKE 

TRAIN PIPE 



SPRING 




EXHAUST FROM 

STEAM BRAKE 

CYLINDER 



Fig. 66 VACUUM-OPERATED 
GRADUABLE STEAM BRAKE VALVE 
(Mark IV) 



bottom of the vacuum cylinder to the train pipe. On the upper side 
of the piston there will also be a normal vacuum due to the connection 
of the upper portion of the piston with the vacuum chamber through 
the ejector release valve, and the piston will be at its lowest position 
duo to the action of the spring. Steam at boiler pressure is supplied 
to the chamber above the two valves and the steam brake cylinders 
are empty of steam, the cylinders being open to atmosphere past the 
exhaust valve. 



148 



When the Driver's brake valve is moved towards the "on" 
position, the vacuum in the train pipe is reduced due to air being 
admitted through the brake valve. This also admits air to the 
underside of vacuum cylinder piston which moves upward, causing 
the steam brake cylinder exhaust valve to close. Further movement 
next raises the pilot valve to admit steam below the balance piston 
which causes it to lift, thus allowing the main steam valve to open 
and pass steam direct to the steam brake cylinder. This condition 
continues until the steam pressure in the steam brake cylinder, 
acting downwards on the exhaust valve, is just sufficient to 
overcome the upward pressure on the vacuum cylinder piston, 
which is then forced down until the valves close. 

Further downward movement of the air piston, when the vacuum 
in the train pipe is re-created, permits the steam brake exhaust valve 
to open and release steam from the brake cylinders to exhaust. 

Manual Operation. Manual operation of the steam brake only, 
for use when running light engine or when working an unbraked 
train, is carried out by means of a lever and quadrant incorporated 
in the brake unit. The operating lever gives movement to valves 
through the medium of a compression spring so arranged that the 
amount of steam brake application is proportional to the com- 
pression of the spring, full application of the brake is obtained when 
this lever is placed in the last notch, the spring box then being solid. 

The brake arrangement which was fitted to the former L.M.S. 
standard locomotives is very similar to the B.R. standard, except 
for the Driver's brake application valve, which is shown in Fig. 67. 
This is a combined steam and vacuum brake application valve and 
is designed to admit steam to the brake cylinders as the train pipe 
vacuum is reduced and to release steam from the steam brake 
cylinders as the vacuum is restored. The normal or "off" position 
is when the small ejector is in operation and a vacuum is main- 
tained in the train pipe and on the inner side of the air piston, the 
opposite side of the air piston being under atmospheric pressure 
entering through the hollow piston rod, the air pressure holding the 
piston in the "in" position which, through the fulcrum lever, 
maintains the steam brake supply plug in the closed position and at 
the same time allows the exhaust passage and ports to be in com- 
munication with the pipe to the steam brake cylinders. 

A movement of the application valve handle to the "on" position 
admits air into the train pipe through the holes in the application 
valve disc and to the inner side of the air piston, the air piston then 
being in equilibrium, the steam behind the steam plug exerts a 
pressure, forcing the steam plug out. The movement of the steam 
plug spindle closes the passage and ports, preventing the steam 



149 



TRAIN PIPE 




EXHAUST 
PORT 



LIVE STEAM 

SUPPLY T ° STEAM 

(Sicam pipe conncctio" BRAKE 

on remo.e ,.dc) CYLINDER 



Fig. 67 DRIVER'S BRAKE VALVE 



passing out to exhaust and at the same time, through the fulcrum 
lever, forces the air piston out. Steam from the plug passes down the 
steam pipe to the engine and tender steam brake cylinders. A cam, 
which is part of the application valve disc, ensures the positive move- 
ment of the lever to open the steam plug as the vacuum is being 
destroyed. 

Replacing the application valve to "off" position, the vacuum will 
be restored in the train pipe and inner side of the air piston. The 
atmospheric pressure acting on the outer side of the air piston will 
exert a pressure to force the piston in and through the fulcrum 
lever, close the steam plug, and allow the steam in the steam brake 



150 



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Fig. 68 



cylinders to escape to exhaust. For use when the engine is standing, 
a hook is provided to hold the fulcrum lever in the inward position, 
ensuring steam plug being held closed, avoiding the need for using 
the small ejector and resulting in a saving of steam. 

Fig. 68 illustrates a brake arrangement which is in common use 
on the large former G.W.R. locomotives. In this arrangement the 
engine and tender, in addition to the train, are provided with 
vacuum brakes. The arrangement is very similar to that previously 
described. 

The four-cone ejector is located on the right-hand side of the 
boiler outside the cab. The steam to the ejectors is provided from 
steam valves located on the Driver's brake application valve. The 
main ejector steam valve supplies steam to the three cones and the 
small valve supplies steam to the remaining single cone. The vacuum 
pump is provided to maintain the vacuum when running, and this rs 
supplemented as necessary by the single-cone ejector (small ejector). 
The three-cone ejector (large ejector) is coupled to the train pipe 
extension to the Driver's brake application valve through the check 
valves. The single-cone ejector (small ejector) and the pump are 
coupled to the train pipe at the front end of the locomotive, the latter 
by way of the retaining valve. The arrangement of these pipes is the 
result of protracted experiments to obviate the possibility of water 
which might accumulate in the flexible train pipe connections through 
condensation caused by the admission of air into the train pipe 
during cold or wet weather. The action of the small cone ejector and 
pump tends to draw any moisture towards the front end of the train 
pipe on the locomotive, thus keeping the moisture away from the 
flexible coupling of the train pipe. 

The vacuum pump (Fig. 69) consists of a piston which reciprocates 



TRAIN PIPE 



TRAIN PIPE RELIEF VALVE 

A LUBRICATOR E 

m 



PUMP 




B. INLET VALVES 
D. OUTLET VALVES 



VACUUM 
RETAINING VALVE 



AIR PUMP 



Fig. 69 VACUUM PUMP 
Former Great Western Railway Locomotives 



152 



in the cylinder, being driven directly from one of the locomotive 
piston crossheads. A chamber extends above the cylinder and flat 
clack valves (B) are fitted between the chamber and the cylinder, one 
at each end. Similar flat clacks (D) are also fitted at each end of the 
cylinders which lift to provide access to the atmosphere. Train 
pipe (A) provides communication to the retaining valve. 

As the piston travels from the left-hand cover air is induced from 
the chamber and pipe (A), past clack (B), clack (D) being held on 
its seating by the pressure of the outside atmosphere. On the return 
stroke the air previously induced into the cylinder is expelled from 
the cylinder past clack (D) into the atmosphere, valve (B) being held 
on its seating by the air being expelled. The pump is double acting 
so that when air is being induced from the train pipe on one side of 
the piston, the air induced during the previous stroke is being 
expelled at the other side. 

The retaining valve is shown in Fig. 70. Position 1 shows the 



TO TRAIN PIPE 




POSITION I 



POSITION 2 



Fig. 70 RETAINING VALVE 
Former G.W.R. Locomotives 

valve connected at (A) to the pump and (B) to the train pipe and at 
(C) to the vacuum reservoir. There will thus be always the same 
amount of vacuum above the small piston (D) and also the large 
piston (E) as in the train pipe, as the two pistons are connected by 
means of a hole through the piston rod. In the space between the 



153 






piston heads there will be the same amount of vacuum as in the 
reservoir. When running, air is extracted from the train pipe by the 
vacuum pump. 

When the brake is applied air enters the train pipe and then flows 
underneath the large piston (E) and raises the pistons to the position 
shown in Position 2. It will be noted that the piston (D) seals the 
passage (B) and being raised above the passage (A) opens communi- 
cation between the latter and the passage (C), and the effect of the 
pump being transferred to maintaining the vacuum in the reservoir. 

The vacuum relief valve or pepper-box valve on the connecting 
pipe prevents the vacuum in the reservoir from rising to an excessive 
amount and preventing the brake pistons from returning to their 
normal position when the brake is released. The relief valve is set 
to lift at 23 in. vacuum. 

Returning to Fig. 68, when the brake is applied air is admitted to 
the train pipe and from there to the undersides of the brake pistons 
on the engine, tender and train. This action of the retaining valve 
transfers the effect of the pump to the reservoir side of the brake 
cylinders, therefore maintaining the reservoir vacuum. 

When the brake is released the single-cone ejector should be used, 
whereas the three-cone ejector (large ejector) should only be used 
when it is necessary to create the vacuum quickly. By avoiding the 
use of the three-cone ejectors a considerable amount of steam will 
be saved. 

Another brake arrangement in common use is shown in Fig. 71. 

A combined ejector and Driver's brake application valve is fitted; 
this may be of the Dreadnought or solid jet type. (Fig. 72.) 

A diagrammatic view of the Dreadnought type of combined 
ejector and brake valve is shown in Fig. 73. 

The diagram illustrates the ejector in the "brake off" position, 
i.e. the brakes are being released, the cam on the main shaft being 
raised to open the large ejector steam valve and admit steam to the 
large ejector. At the same time steam passes to the small cone 
through the small ejector steam valve. This valve should be set by 
hand so as to withdraw and reduce the steam pressure to about 
120 lb., which is the pressure at which this cone is designed to give 
its greatest efficiency. 

Under the influence of both cones air is drawn rapidly from the 
train pipe past the large ejector air clack, the small ejector air clack, 
main air clack, and through cavity (D) in the air disc by way of 
ports (C and B), these ports being in full register in this position of 
the handle. At the same time air is drawn from the vacuum chambers 
on engine and tender past release valve. 



154 




Fig. 71 




155 



Boor 

AIR DISC WITH HANDLE 

SHAFT. WITH NUT AND LEVER 

LARGE EJECTOR STEAM VALVE GUIDE NUT 

LARGE EJECTOR STEAM VALVE CLACK 

LARGE EJECTOR STEAM VALVE SEATING 

LARGE EJECTOR STEAM VALVE SPINDLE 

LARGE EJECTOR STEAM VALVE PACKING BOX 

LARGE EJECTOR STEAM VALVE GLAND 

SMALL EJECTOR STEAM VALVE SPINDLE 

SMALL EJECTOR STEAM VALVE HANDLE 

LARGE CONE (INNER PART) 

LARGE CONE (OUTER PART) 

EJECTOR EXHAUST BARREL 

LARGE EJECTOR EXHAUST NOZZLE 

SMALL CONE (INNER PART) 

SMALL CONE (OUTER PART) 

LARGE CAP 

SMALL CAP 

DRIP CONNECTION. WITH NUT AND BALL 

VACUUM REDUCING VALVE COMPLETE 

AIR CLACK (BACK) 

AIR CLACK (FRONT) 

AIR CLACK GUIDE (BACK) 

AUXILIARY APPLICATION VALVE 

AUXILIARY APPLICATION VALVE CLACK 

AUXILIARY APPLICATION VALVE LEVER 

WITH PINS. LINK AND SPRING 
STEAM PIPE UNION AND RING 
TRAIN PIPE UNION AND RING 
EXHAUST PIPE UNION AND RING 
SMALL AIR CLACK GUIDE 
SMALL AIR CLACK 
RELEASE VALVE 




Fig. 72 DREADNOUGHT EJECTOR 



156 








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157 






In the "running position" of handle, the cam lowers the large 
ejector steam valve on to its seat, thus cutting off the supply of 
steam to the large ejector. The connection between the small cone 
and the train pipe through cavity (D) in the air disc remains open 
and the small ejector maintains the working vacuum whilst the train 
is running. Operation of the auxiliary application valve in this 
position admits air to the train pipe and enables light brake appli- 
cations to be made for controlling the train speed. 

As the handle is moved towards the "brake on" position the 
connection through the cavity (D) is progressively closed. At the same 
time ports (E and F) in the air disc gradually uncover ports (B and 
A) in the ejector face and air is admitted to the train pipe to apply 
the brake. This air is prevented from passing to the engine and 
tender vacuum chambers by the non-return valve in release valve. 

In the full "brake on" position ports (A and B) in the ejector 
face are completely open to atmosphere through ports (F and E) 
in the disc and the brake is rapidly applied. At the same time the 
small cone is isolated from the train pipe by the wall of cavity (D) 
and draws only on the engine and tender vacuum chambers past the 
release valve. In this way the maximum possible locomotive brake 
power is assured in emergency applications. 

The air passages in the ejector arc so arranged that, in all cases, 
air from the train pipe is drawn past two gun metal clacks before 
coming in contact with the steam. When steam is cut off from the 
cones and a vacuum is left in the train pipe, these clacks prevent 
moisture, and more especially smokebox gases, being drawn into 
the train pipe. 

The ball valve, located below the relief valve, communicates 
with the chamber between the two ejector clacks and the main clack. 
When a vacuum is created in the instrument the ball is drawn to its 
seal, but falls olfas soon as steam is shut oil" and the vacuum drops. 
Should ejector air clacks be leaking it provides an outlet for any 
vapour or steam. Should the main air claek leak, it admits air from 
the atmosphere being drawn into the train pipe and so prevents any 
tendency to draw vapour and smokebox gases through ejector air 
clacks. 

The vacuum relief valve is a spring-loaded valve which limits the 
degree of vacuum carried in the train pipe. When the point is reached 
at which it is set, atmospheric pressure above the valve overcomes 
the resistance in the spring and the valve opens to admit air to the 
space above the main clack, thus preventing the creation of a higher 
vacuum in the train pipe. 

The release valve enables atmosphere to be admitted direct to 
the vacuum chambers so that the brake can be released by hand 



Fig. 73 



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when the locomotive is uncoupled and when steam is not available. 

Fig. 74 shows a diagrammatic arrangement of the solid jet type 
combined ejector and brake valve. 

The left-hand illustration is of the ejector in "brake off" position, 
the cam on the main shaft being raised to open the large ejector 
steam valve and admits steam to the large cone. At the same time 
steam passes to the small cone through the small ejector steam valve 
which is opened just sufficiently to admit the quantity of steam 
necessary to maintain the required vacuum. 

Under the influence of both cones air is drawn rapidly from the 
train pipe past the air clacks, also from the chambers on the engine 
past the valve and the ball. 

In the "running position" of the Driver's handle, the cam lowers 
the large steam valve on to its seat and the working vacuum is 
maintained throughout the running train by the small cone only, 
which is prevented from drawing back on the exhaust branch of the 
large ejector by air clack closing down. 

The "partial application" shows the first admission of air as the 
Driver's handle is moved towards the "brake on" position. The 
finger on cam engages the lifter to open an auxiliary valve, and after 
this valve has attained its full lift the shoulders on the wing of the 
lifter come in contact with the main admission valve. 

To effect isolation of the main train pipe from the action of the 
small ejector in the full "brake on" position, the main air clack is 
provided with a spindle extension actuated by the sleeve. Bell crank, 
worked from the cam, is operated increasingly as the Driver's handle 
comes to the "full on" position. In the "full on" position illustrated 
the arm of the bell crank has fully depressed the sleeve, taking with 
it the main clack, so shutting off the small ejector connection from 
the train pipe. The actual holding down of the main air clack is 
through the compression spring, which is capable of adjustment 
as regards tension by means of the backnut. The light spring only 
serves the purpose of holding this assembly together to prevent 
chatter. 

When the brake is applied and the small ejector is left drawing 
upon the cavity below the small air clack, the large air clack remains 
closed and the main air clack is held closed by the bell crank, the 
valve lifts and connects the engine chambers to the ejector. In this 
way the maximum possible locomotive brake power is assured in 
emergency applications. To provide against the creation of an 
excessive vacuum in the top side of the brake cylinders the main air 
clack is held down by the bell crank through the tension of the 
compression spring which is so arranged that, when the brake is 
"full on" and the cavity all round the bell crank and the train pipe is 



Fig. 74 



160 



in a state of atmospheric pressure, the creation of anything exceeding 
21 in. above the main air clack will cause the atmospheric 
pressure under it to overcome the resistance of the compression 
spring and so allow the main air clack to lift, and this acts as an 
internal relief valve, obtaining its air from the train pipe which is in 
a state of atmospheric pressure due to the main admission valve 
being open. 

A ball valve is located in the cavity between the two ejector clacks 
and the main clack, and is drawn to its seat when a vacuum is 
created, but falls off as soon as steam is shut off and the vacuum 
drops. Should the small and large air clacks be leaking, it provides 
an outlet for any vapour or steam. Should the main air clack leak, 
this ball valve prevents any tendency to draw vapour and smoke box 
gases through the small and large air clacks. The ball above the relief 
valve serves to allow any moisture to escape. 

For the purpose of maintaining the brake operative on a "dead 
engine" which requires moving and may have vacuum brake 
cylinders without ball valves, the ball is provided within the ejector. 
By this means, when a vacuum is created in the train pipe, air is 
also drawn from the chambers of the dead engine, thus created in 
the train pipe; air is also drawn from the chambers of the dead 
engine, thus creating a vacuum above and below the brake pistons. 
This necessitates that the Driver's handle on the dead engine ejector 
is in the "running position". 

The vacuum relief valve is a spring-loaded valve which limits the 
degree of vacuum carried in the train pipe. When the point is 
reached at which it is set, the atmospheric pressure below the valve 
overcomes the resistance of the spring and the valve opens to admit 
air to the space below the main clack, thus preventing the creation 
of a higher vacuum in the train pipe. 

The release valve operates in the usual manner. 

Fig. 75 shows the brake arrangement on ex-L.N.E.R. A. 3 
Pacific locomotives. 

The combined ejector and Driver's brake valve is of the com- 
bined type and the vacuum brake cylinders arc of the combined 
"C" class without release valve. 

On the arrangement Figs. D and A illustrate the normal running 
position with the brakes "off" and the small ejector maintaining the 
vacuum in the train pipe and vacuum cylinder. Figs. F and B 
illustrate the position when the brake is in the "on" position. 

It will be noted that air has entered the train pipe through the 
Driver's control handle and has acted on the underside of the brake 
cylinders causing the brakes to be applied. The effect of the small 



161 









ejector has been cut off from the train pipe and its whole effect 
transferred to maintaining the vacuum in the vacuum chamber on 
the top side of the brake cylinders so as to overcome any slight 
leakages which might decrease the vacuum. 

Vacuum Brake Cylinders 

Figs. 76-79 show four types of vacuum brake cylinder which are 
in common use on British Railways. Fig. 76 illustrates the combined 
"C"-type cylinder which is in general use on carriage and wagon 
stock as no vacuum chamber is required, this being incorporated in 
the design. The piston is rendered airtight by means of a rubber 
rolling ring (9). 

Fig. 79 illustrates a similar cylinder, but the piston is fitted with a 
slipping rubber band instead of a rolling ring, and this type was 
adopted as standard for British Railways stock. 

With rolling ring cylinders the vacuum chamber side vacuum is 
obtained either through a non-return ball valve in the piston or in 
an external fitting on the cylinder. These allow air to flow from the 
chamber side and shut when the brake is applied, so as to maintain 
the vacuum in the vacuum chamber. 

The former G.W.R. slipping-band type of brake cylinder does not 
require ball valves, the air being drawn past the rubber band which, 
when the piston is right down in the "off" position, lies opposite a 
relieving groove. 

When the brake is applied, air which enters the train pipe through 
the Driver's brake application valve, or, for that matter, the Guard's 
brake application valve, passes through the brake cylinder flexible 
connecting pipe and enters into the bottom of the brake cylinder and 
at the same time forces the ball valve on to its seating on the passage 
leading to the vacuum chamber, in the case of the rolling ring 
cylinder, thereby retaining the vacuum on the top side of the brake 
piston, the air having access to the bottom of the piston only. 

When the brakes are released, the action of the ejector causes 
air to be drawn from the underside of the brake piston. When the 
vacuum reaches and commences to exceed that in the vacuum 
chamber (top side of brake piston) the ball valve lifts from its 
seating until the vacuum on both sides of the brake piston is the 
same, and being in equilibrium the brake piston drops to the 
bottom of the brake cylinder by virtue of its weight. 

With the slipping-band cylinder, when the vacuum in the train 
pipe commences to exceed that in the vacuum chamber, the brake 
piston drops to the "off" and air from the vacuum chamber is 
drawn past the rubber band opposite the relieving groove. 



162 



163 



Fig. A 

ENGINE BRAKES 
"OFF" 



Fig. 75 BRAKE ARRANGEMENT Former L.N. E.R. A.3 Pacific Locomotive 




AIR ADMISSION 
VALVE 



CAM FOR OUTER 
AIR VALVE 



SECTION THROUGH 


' t T=¥ TRAIN PIPE 




STEAM AND AIR 






ADMISSION VALVES 


•J SMALL J 






VACUUM EJECTOR 1 


WTs- v 




CHAMBER 


^^l U 




PIPE 


1 * 



RELEASE 
VALVE 



DRIVER'S 

CONTROL 

HANDLE 



VACUUM CHAMBER 
PIPE 



164 



ARROWS DENOTE 

DIRECTION OF AIR 

DURING APPLICATION 

OF BRAKE 



CYLINDER AT 
■BRAKE ON' POSITION 



PISTON 



CAST IRON 
NNER CYLINDER 




VALVE OPEN 



VALVE D GLAND 



BRAKE SHAFT 



Fig. 76 VACUUM BRAKE CYLINDER 

C. Class Combined 



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BALL AND RELEASE 

VALVE WITH 

CONNECTIONS TO 

RESERVOIR AND 

TRAIN PIPE 




BALL VALVE 




PISTON ROD 
GLAND PACKING 



Fig. 78 VACUUM BRAKE SEPARATE CYLINDER 

C. Class 



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166 




: ROLLING RING 



JOINT RING 



^CYLINDER 
PISTON ROD CASING 



REVERSIBLE 

HOSE PIPE 

CONNECTION 



PISTON ROD 



Fig. 79 VACUUM BRAKE SEPARATE CYLINDER 

F. Class 



The Westinghouse Automatic Air Brake 

This is a compressed-air brake and Fig. 80 shows a diagrammatic 
•arrangement of the system as applied to a locomotive. 

On a steam locomotive, air is compressed by a steam-driven pump 
which is automatically controlled by means of a "governor" (see 
Fig. 8 1) positioned on the pump steam supply line. The governor 
is usually set to maintain a pressure of 90 lb. per sq. in. in the main 
reservoir, which pressure is indicated by the red hand of the 
duplex air pressure gauge. 

The compressed-air supply from the main reservoir passes through 
the Driver's brake application valve (Fig. 82) into the train pipe by 
means of the feed valve (Fig. 83) which automatically maintains the 
air pressure in the train pipe at 70 lb. per sq. in. when the Driver's 
brake application valve is set in the "running" position. 

The brake equipment on the engine, tender and each vehicle of 
the train fitted with this type of brake is a triple valve, auxiliary ait- 
reservoir and brake cylinder. 




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168 



PIPE ATTACHED 
TO MAIN 
RESERVOIR 



PISTON SPRING 



STEAM 
INLET 




ADJUSTING SCREW 



REGULATING SPRING 



DIAPHRAGM 



EXHAUST 



PISTON 



STEAM VALVE 
AND ROD 




STEAM VALVE OPEN 



STEAM VALVE SHUT 



Fig.8l WESTINGHOUSE BRAKE 
AIR COMPRESSOR GOVERNOR 



TO TRAIN 
PIPE 




PISTON 



DIAPHRAGM 

Fig. 83 FEED VALVE 




169 



BRAKE RELEASE 
POSITION 



. EXHAUST 




TO MAIN / EXHAUST 

RESERVOIR 

TO BRAKE PIPE 
AUTOMATIC BRAKE 



REGULATING 

FEED 

VALVE 





Fig. 82 

DRIVER'S BRAKE 

APPLICATION VALVE 



170 



The triple valve (Fig. 84), as the name implies, has three duties to 
perform: (I) charging the auxiliary reservoirs, (2) applying the 
brakes, and (3) releasing the brakes. 

When the locomotive is coupled to the train, air is admitted to 
the train pipe after the cocks between the locomotive (tender) and 
the train have been opened. Driver's brake application valve handle 
is then placed in the "release" position (see Fig. 82) until the black 
hand of the duplex air gauge indicates that the normal train pipe 
working pressure has been reached, after which the brake valve 
handle should then be placed in the "running" position. 

The air in the train pipe passes into each triple valve (see Fig. 84) 
and forces up the piston which is connected to a slide valve. 
In this position compressed air from the train pipe charges the 
auxiliary reservoirs through the grooves until the air pressure 
equals that in the train pipe, at the same time the slide valve 
establishes communication between the brake cylinder and 
exhaust passage through the cavity. 

When the brake is applied the air pressure in the train pipe is 
reduced and the piston is moved downwards by the greater air 
pressure in the auxiliary reservoir. The piston, having a limited 
movement, without acting on the slide valve, closes the feed groove 
and at the same time moves the graduating valve from its seating, 
thus opening the port. Further downward movement of the piston 
takes with it the slide valve which closes the exhaust passage and 
brings the port into communication with the passage to the brake 
cylinder, resulting in air entering the brake cylinder from the 
auxiliary reservoir and the brakes being applied. Further downward 
movement of the piston and the slide valve is arrested with the 
decrease of pressure above the piston, i.e. in the auxiliary reservoir, 
due to the flow of air to the brake cylinder, and when the pressure 
in the auxiliary reservoir is reduced slightly below that in the train 
pipe, the piston moves up sufficiently to close the graduating valve 
(but not sufficient to move the slide valve). By further reducing the 
train pipe pressure any degree of brake pressure can be attained. 
The brakes are fully applied, however, when the train pipe pressure 
has been reduced by 25 lb. per sq. in., and any further reduction, 
under normal braking conditions, is merely a waste of compressed 
air. 

When an emergency application of the brake is made, the piston 
is forced downwards to the limit of its stroke and seals on the 
leather gasket. When this occurs, the slide valve uncovers fully the 
passage to the brake cylinder, thus allowing the air from the auxiliary 
reservoir to enter quickly the brake cylinder and apply the brake's 
with full force. 



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172 



173 






When trains are worked with two locomotives, the brakes should 
be entirely under the control of the Driver of the leading engine. 
On the train engine the isolating cock to the main reservoir pipe 
under the Driver's brake application valve must be closed and the 
brake valve placed in the "release" position. Care should be taken 
to ensure that this isolating cock is opened on the train engine 
whenever the leading engine is uncoupled. 

If the train should become divided, or a flexible coupling burst, 
the brakes will be automatically applied on both portions of the 
train owing to the reduction in train pipe pressure. The Driver, 
under these circumstances, should move his brake application valve 
to the "on" position, as when making an ordinary application. 
This will prevent the air escaping from the main reservoir and 
assist the stopping. 

The same applies when the brake is applied by the cock in the 
guard's van being opened. 

The improved triple valve is shown in Fig. 85; its object is to give 
a closer approach to simultaneous action of all the triple valves on a 
train when the slide valve is moved by applying the brakes, the bulb 
is closed to atmosphere and opened to the train pipe. The local 
reduction of the train pipe pressure thereby produced by the forward 
triple valves of a train causes an earlier action of the rearward triple 
valves, which results in a more nearly simultaneous braking effect 
being produced throughout the train in every case of first setting the 
brakes than was possible with the ordinary triple valve. 

The bulb at the bottom of the valve is made in different sizes 
proportioned to the volume of the vehicle train pipe. 

To release the brakes, air from the main reservoir is admitted by 
means of the Driver's valve into the main brake pipe where it enters 
the triple valve and forces piston and slide valve to their original 
position: the air from the brake cylinders of bulb is then discharged 
to atmosphere and the brakes released. The auxiliary reservoir is 
then recharged through the grooves, past the piston, as in the case 
of the ordinary triple valve. 

Fig. K6 illustrates the brake arrangement of a dual-fitted loco- 
motive; whilst the brakes on the engine are Wcstinghouse, it is 
possible to work coaches equipped with vacuum brakes. This is 
done by means of a proportional valve, which ensures that the 
degree of application and release of the brakes on the engine and 
train are in proportion to each other. 

Westinghouse Brake Cylinder 

The brake cylinder consists of a piston and piston rod which are 
attached to the brake gear in such a manner that the brake blocks 



BODY. 




O O O 

ooo 



Fig. 85 TRIPLE VALVE (Improved) 



are pressed against the wheels when the piston is moved in the 
brake cylinderby air pressure. A spring is fitted which is compressed 
when the brake is applied, and when the brake is released the spring 
expands and returns the piston and brake gear to their original 
position, thus releasing the brake blocks from the wheels. 

To prevent the application of the brakes, which might be caused 
by a slight leakage in the brake pipe to the brake cylinder, the brake 
cylinders are provided with a small groove which establishes 
communication between both sides of the piston when the brake 
piston is in the "oft"" position. If a slight leakage occurs theair will 



174 



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pass through the groove to the atmosphere without moving the 
piston. However, when a considerable quantity of air is admitted 
to the cylinder, as by an ordinary brake application, the piston is 
immediately forced past the groove and the escape of air sealed. 



175 



Questions and Answers 

(1) Q. How is the train pipe vacuum measured? 

A. The vacuum is measured in "inches of mercury" and the 
vacuum gauges on the engine and in the brake vans are 
graduated in inches. A perfect vacuum corresponds to 
approximately 30 in. of mercury, atmospheric pressure or no 
vacuum to zero inches. The regulation of vacuum in the 
train pipe to 21 in. of mercury, which it is important to bear 
in mind, along with other intermediate readings, is only a 
partial vacuum. Each 1 lb. pressure of air extracted is 
represented by 2 in. of vacuum on the gauge. 

(2) Q. What will be the pressure per square inch on the piston when 

the brake is applied fully if 21 in. of vacuum is recorded on 
the gauge before the application is made? 
A. 1(H lb. per sq. in. Atmospheric pressure or the weight of air 
pressing upon the earth's surface is approximately 15 lb. per 
sq. in. at sea level and it has been found that this pressure is 
sufficient to support a column of mercury nearly 30 in. high. 
Consequently every inch of mercury in the column represents 
a pressure of \ lb. per sq. in., so that 21 in. indicated in the 
vacuum gauge represents lOi lb. per sq. in. which can be 
exerted upon the piston head when the brake is applied. 
Some idea of the power available can be obtained by con- 
sidering a 20-in. diameter cylinder. The area of the piston is 
314 sq. in. and the pull produced on the brake piston rod 
would be lOi x 314 lb., which equals 3,297 lb. or more 
than 1 ton. 

(3) Q. How does the combination ejector create vacuum? 

A. A jet of steam issuing at high velocity from a cone of special 
shape within the ejector (see Fig. 64) carries the surrounding 
air forward by frictional contact through a second and 
larger cone, known as the air cone, to exhaust in the smoke- 
box. 

The removal of air in this manner from the space in the 
immediate vicinity of the steam jet sets up a partial vacuum 
inside the ejector; air, in its endeavour to fill this space, flows 



176 



past the non-return valve from the train pipe and other 
portions of the brake apparatus connected to it. 

In this way it is possible to maintain the desired amount of 
vacuum at will in the train pipe and connections so long as 
the ejector is kept at work and the brake is not applied. The 
combination ejector contains two separate ejectors con- 
structed on the above principle, each one independent of the 
other and possessing its own non-return valves. 

(4) Q. What purpose do the non-return valves serve? 

A. The non-return valves and the air lock chamber are for the 
purpose of preventing loss of vacuum through the ejector 
cones when the ejector is shut down, and also to guard 
against steam and smokebox gases being allowed to enter 
the train pipe and connections. 

(5) Q. How is the train pipe vacuum prevented from rising above 

the regulation amount of 21 in.? 

A. A vacuum relief valve is provided for the purpose. This is a 
spring-loaded valve capable of being adjusted so that it will 
open and admit air to the train pipe as soon as the regulation 
vacuum of 21 in. has been exceeded. The relief valve is 
generally mounted inside the cab in an accessible position 
and contains a fine-gauge filter to prevent entry of dust and 
dirt into the train pipe. This filter requires to be cleaned and 
examined periodically by the Shed Staff. If the filter or the 
air holes become choked with dirt or any other obstruction, 
free passage of air to the relief valve is prevented and may 
result in an excessive amount of vacuum being created in the 
train pipe. 

(6) Q. Describe one type of vacuum brake cylinder in common use. 
A. A type of vacuum brake cylinder frequently used on 

passenger and freight vehicles is illustrated in Fig. 76. 

It will be seen to consist of a vacuum reservoir and 
cylinder combined, the cylinder proper being open at the top 
and enclosed within the reservoir. The brake piston is of 
fairly deep section and is kept airtight within the cylinder by 
a rubber rolling ring nipped between the piston head and the 
cylinder wall. The piston rod passes through the bottom of 
the cylinder and is kept airtight by a gland. 

The brake cylinder is connected to the train pipe by a small 
flexible hose attached to the ball valve housing at the base of 
the vacuum chamber. 

The purpose of this ball valve is to control the movement 



177 



of the brake piston in accordance with the variations in the 
train pipe vacuum, and also to provide a means of releasing 
the brake by hand when necessary. 

This ball valve can close the vacuum chamber port, or it 
can place the lower side of the brake piston and the vacuum 
chamber in communication with each other and with the 
train pipe when off its seating. 

Running with the brake off, the ball valve is unseated, 
leaving the train pipe in communication with both sides of 
the piston, which will then be in equilibrium and resting by 
its own weight at the bottom of the cylinder. Immediately 
air is admitted to the train pipe it passes up the connecting 
pipe and forces the ball valve to its seating on the port 
leading to the vacuum chamber, thereby retaining the 
vacuum on the top side of the piston. The port to the 
underside of the piston is, however, left open, and the air 
accordingly flows into the bottom of the cylinder, lifts the 
piston and applies the brake. 

Restoration of the train pipe vacuum extracts the air from 
below the piston until the vacuum below equals that in the 
chamber above, after which the piston, being equalised, will 
sink to the bottom of the cylinder by its own weight, allowing 
the brake to release. At the same time the ball valve will 
drop away from its seating on the chamber port, leaving 
both sides of the piston in communication with the train 
pipe, ready for the next brake application. 

The hand release arrangement is effected by a ball valve 
enclosed inside a sliding cage connected to an external lever, 
as shown in Fig. 76. When the release cord is pulled, the 
cage is displaced, forcing the ball valve away from the 
vacuum chamber port, thereby placing both sides of the 
brake piston in communication with the train pipe. 

(7) Q. Passenger vehicles are fitted with a communication cord 
which, when operated, gives an indication to the Driver in 
order to stop the train in case of emergency. Describe how 
the arrangement operates. 
A. The communication cord consists of a chain passing through 
each compartment of the coach and connected at the end of 
the vehicle to the passengers' alarm valve and indicating 
disc. 

The alarm valve, when operated by the chain being 
pulled, opens and allows air to enter the vacuum train pipe, 
causing a reduction in vacuum of 5 to 10 in., which is 



178 



179 






sufficient to apply the brake with moderate force and to 
attract the Driver's attention. 

(8) Q. Describe the brake action on a train fitted throughout with 
the vacuum automatic brake. 
A. The brake is applied by the pressure of air being admitted 
through the ports of the Driver's application valve, passing 
down the train pipe from the engine to the train. 

During release, the blocks on the leading vehicles will be 
freed first and for this reason the small ejector only should be 
used for release purposes when the train is in motion, in 
order to avoid surging and shocks on the drawgear caused 
by the early release in front and continued retardation of the 
rear portion of the train, which would be intensified if the 
large ejector was used. 

(9) Q. How should the brake be handled to obtain the best results? 
A. In the case of "service application", in which full brake power 
is not called for, the Driver should begin by destroying 7 to 
10 in. of train pipe vacuum and should hold this application 
until he feels the slight check which will indicate the brake 
has taken hold. This is known as "setting the brake"; after 
this, the brake block pressure can be varied at will by regu- 
lating the train pipe vacuum to suit requirements of the stop. 
To make a full-power application, the Driver would put 
the application valve right over to "full on" position in a 
single movement, destroying all train pipe vacuum, and 
would leave it thus until speed was reduced sufficiently to 
permit the application to be somewhat eased. 

(10) Q. Name a few bad faults to be avoided when handling vacuum- 
fitted trains. 

A. Do not "see-saw" the brake handle between "running" and 
"brake on" positions several times when commencing an 
application. This practice retards the action of the brake 
cylinder ball valves and will increase the time required to 
"set" the brake. 

In all normal cases avoid the use of the large ejector to 
release the brake except when the train is stationary. 

Do not bring the train to rest with all the train pipe 
vacuum destroyed and the brake applied with full power. 

Ease the application in the final stages by allowing the 
train pipe vacuum to build up slowly to about 12 in., which 
will prevent complete release of the engine brake and also 
the risk of locked wheels on the train. 



(11) Q. How would the Driver carry out his test of the brake on an 

engine fitted with the automatic steam and vacuum brake? 

A. He would test for obstruction in the engine train pipe by 
applying the large ejector with first the front and then the 
rear hose bag off the stopper; in neither case should the 
vacuum gauge show more than 3 in. of vacuum. If the 
gauge shows an appreciable amount of vacuum with either 
pipe off the plug, an obstruction in the train pipe is indicated 
and must be located and removed. Having replaced the 
hosebags on the stoppers he should then create the full 21 in. 
of vacuum in the train pipe, using the small ejector for the 
purpose; shut off the ejector and note the time taken for the 
vacuum to fall to 12 in. on the gauge. 

If this is less than 20 seconds the train pipe leakage is 
excessive and should be located. 

The large ejector should be tested and the brake worked 
once or twice by the application valve to prove the 
mechanical parts of the apparatus. 

(12) Q. If bad leakage on the train pipe is indicated by this test, what 

points should be looked at to find the fault? 
A. See that both vacuum hose pipes are properly on the stop 
plugs and that the rubber washers are good. Test the drip 
valves for leakage and all joints in the train pipe, using the 
torch-light flame for the purpose. See that the disc of the 
application valve is not sticking away from the face and 
check all the train pipe connections on the footplate. If no 
leakages are disclosed, suspect the non-return valves in the 
combination ejector. Whilst making the above test the small 
ejector should be kept at work and the brake valve should be 
left in "running" position. 

(13) Q. How would you test engines fitted with the vacuum brake 

before leaving the shed ? 
A. Examine the flexible train pipes and see that the couplings fit 
properly on the plugs. Then put the brake handle to the 
"on" position, close the auxiliary release valve and open the 
small ejector steam valve slightly. This will extract air from 
the top sides of the pistons and admit air to the bottom sides 
and train pipe and will also deposit in the smokebox any 
water which may be in the exhaust pipe instead of throwing 
it out over the boiler, as may be the case if the large ejector 
was suddenly opened after the engine had been standing for 
some time. Close the small ejector and watch the chamber 



180 



side needle on the gauge, which will fall if the ball valve 
leaks. If the needle remains stationary, then test the train 
pipe side by creating 21 in. with the application valve in 
"running" position, close the steam valve and watch the 
gauge. If the vacuum is rapidly destroyed, the defect must 
be located and made good. 

The large ejector must be tested separately, preferably 
outside the shed, whilst the small ejector remains shut. Then 
test the train pipe on the engine by taking first the front 
hosepipe and afterwards the rear hosepipe off the plugs 
separately, and opening the large ejector fully and then 
closing it; if any vacuum is registered on the train pipe side 
of the gauge when the ejector is closed whilst either of the 
hosepipes is off the plug, a stoppage or obstruction in the 
train pipe is indicated, which must be put right. 

(14) Q. On engines fitted with vacuum brake only, how would you 

decide if a chamber-side leakage was internal or external? 

A. Create a vacuum on both sides, close the small ejector and 

leave the application valve in "running" position. If the 

chamber-side pointer should fall it will be an external leakage. 

(15) Q. How would you test for a faulty ball valve, burst diaphragm 

or faulty rolling ring? 

A. Create 21 in., close the small ejector and apply the brake 
quickly, returning the application valve into "running" 
position. A fault will be shown by the chamber-side needle 
falling and the train pipe needle rising until equal. 

(16) Q. Is it possible to have a defect without indication on the 

engine vacuum gauge? 

A. Yes, an obstruction in the train pipe might prevent the 
creation of vacuum in the train, but the engine gauge would 
show the correct amount of vacuum. It would be necessary 
to test the engine with the vacuum hosepipe off the plug, as 
previously explained. (It should be borne in mind that the 
vacuum gauge shows the degree of vacuum but can give no 
indication of the quantity of air the ejector can eject to 
overcome leakage. The small ejector may maintain 21 in. 
of vacuum on the engine alone, but when coupled to the 
train is unable to create or maintain the requisite vacuum. 
The test for this is by the use of a disc with a standard size 
leak-hole; this is carried out by the Fitting staff at the shed 
or by C. & W. staff when in traffic. See General Appendix 
and Supplement "Working of Vacuum Brake".) 






181 






(17) Q. How should the brake be operated when two engines, 

coupled together, are attached to a vacuum-fitted train ? 
A. It is the duty of the Driver of the leading engine to create and 
maintain the vacuum and to operate the brake. The ejectors 
on the second engine must be kept closed, but the Driver of 
the second engine is not relieved from responsibility of the 
due observance of all signals affecting the working of the 
train and in case of need he must apply the brake. 

(18) Q. How does the compressed air used in the Westinghouse 

brake system apply the brake? 

A. By the air being admitted to a brake cylinder and forcing the 
piston out, which by means of connecting rods and levers 
forces the brake blocks against the wheels. 

(19) Q. What essential parts of the brake are fitted to engine and 

tender carriage or other vehicle? 

A. An auxiliary reservoir, triple valve and brake cylinder. 

(20) Q. Where is the pressure which supplies the brake cylinder 

stored ? 

A. In the auxiliary reservoir under each vehicle fitted with the 
brake. 

(21) Q. How much main reservoir pressure should be carried? 
A. 90 lb. per sq. in. 



182 



183 



SECTION 9 
AUTOMATIC TRAIN CONTROL 

Automatic train control is the name given to the various systems 
which give an audible and, in some cases, a visual indication in the 
engine cab of the position of a distant signal, followed by a brake 
application where necessary. There are three systems in operation in 
this country: — 

(a) The former Great Western Railway system in use on the 
Western Region (Fig. 87). 

(b) The system in use on the Eastern Region (London, Tilbury 
and Southend section) (Fig. 88). 

(c) The British Railways system (Fig. 89). 

The B.R. system which has been developed during the past five 
years will be adopted as the standard for use on all British Railways. 

The methods of operation of the three systems are described in the 
following pages, but it may be helpful to outline the main features 
of each arrangement. 

Former Great Western Railway System 

In this system a fixed ramp about 44 ft. long is situated in the 
4-ft. way. This makes contact with a shoe on the locomotive, and 
when the distant signal is at Caution the ramp lifts the shoe operating 
a switch on the engine, causing a siren to sound in the cab and 
applying the brake after a short delay. The indication can be can- 
celled by the operation of a handle. When the distant signal is in 
the Clear position the ramp is electrified. The lifting of the shoe 
operates the switch as before, but the current picked up from the 
electrified ramp causes a bell in the cab of the engine to ring for a 
short period instead of the siren and without any subsequent brake 
application. 

Eastern Region — London, Tilbury and Southend System 

This is operated by magnetic induction. When the distant signal 
is at Caution a permanent magnet in the 4-ft. way operates the 
apparatus, sounding a horn and applying the brakes after a short 
delay. Cancelling or acknowledging by means of a handle provided 
changes the visual indicator from black to yellow. If the distant 
signal is at Clear, an electro-magnet is energised which cancels the 
effect of the permanent magnet, allowing the horn to sound for a 
short time only and with no subsequent brake application. 



British Railways System 

The British Railways system also works on the principle of 
magnetic induction. When a distant signal is at Caution, the 
permanent magnet operates the receiver on the locomotive, sounding 
the horn and applying the brake after a short delay. Cancelling or 
acknowledging the indication by means of a handle provided changes 
the visual indicator from all black to black and yellow. If the distant 
signal is at Clear an electro-magnet is energised which cancels the 
effect of the permanent magnet and causes a bell to ring in the 
engine cab for a short period. 

FORMER GREAT WESTERN RAILWAY SYSTEM 

General Description 

The primary object of this system is to give audible warning on the 
engine when the train is approaching a distant signal, or passing a 
lower distant signal fixed below a "Stop" signal, and the distant 
signal being in the "On'" (proceed with caution) position, also, in the 
event of this warning being disregarded, to apply the brakes auto- 
matically, so as to ensure the train being pulled up before it reaches 

the home signal. 

Another and distinctive audible indication is also given on the 
engine when the distant signal is "Off" (proceed). 

The audible signals given are the sounding of a siren, indicating 
"be prepared to stop at the appropriate 'Stop' signal", and the 
ringing of a bell, indicating "proceed normally". 

The point at which the audible signals are given is usually about 
440 yd. (200 yd. in multiple aspect signalling areas) before the distant 
signal is reached. Where, however, the distant signal is a lower arm 
on a "Stop" signal, the audible signals are given just as the "Stop" 
signal is passed. 

The apparatus fixed on the permanent way for operating the 
audible signals on the engine is a ramp about 40 ft. long, which is 
fixed between the running rails and is made up of a steel i bar 
mounted on a baulk of timber. The lamp at its highest point is 3£ in. 
above rail level. 

A telegraph wire connects the ramp with a switch in the Signal 
Box through a contact attached to the distant signal arm. 

This switch is attached to the lever controlling the distant signal, 
so that when the lever is operated to place the distant signal to the 
"Off" (proceed) position, an electric battery is connected to the ramp, 
provided the signal has correctly responded to the movement of the 
lever. 



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When the lever is replaced to restore the signal to the "On" 
(proceed with caution) position, the battery is disconnected from the 
ramp. 

The ramp is, therefore, electrified when the distant signal is "Off". 

When the distant signal is "On", the ramp is electrically "dead", 
as is also the case in the event of the battery failing, or the arm not 
responding correctly to the lever, or the telegraph wire breaking. 

The apparatus on the engine comprises a contact shoe with switch, 
an electrically-controlled combined brake valve and siren, and 
an electric bell, in the engine cab. 

The contact shoe is fixed in the centre line of the engine and 
projects to within 2-£ in. above rail level, in which position it is held 
by gravity assisted by a powerful spring. It is capable of being raised 
vertically, and being in line with the ramp it is lifted 1 in. whenever 
a ramp is passed over. This lift of 1 in. is utilised for effectively 
opening a switch attached to the contact shoe. The switch is con- 
nected with the electrically-controlled brake valve and siren in such 
a way that whenever it is opened it results, except as hereafter 
described, in air being admitted through the siren and the brake 
valve to the train pipe, sounding the siren and applying the automatic 
brake on the train. This happens when an engine passes over an 
unelectrificd ramp. The Driver, by acknowledging the warning given 
by the siren, can stop the siren sounding and stop the application of 
the brakes. This he does by raising a handle provided for the purpose. 

When the ramp is electrified by the distant signal being placed in 
the "Off" (proceed) position, the brake valve is not released by the 
engine passing over the ramp, but the bell on the engine rings instead. 
The contact shoe is lifted as before, but the current is picked up from 
the electrified ramp, the effect of which is to cut out, or render 
inoperative, the switch attached to the contact shoe; so that although 
the switch is opened it does not release the valve admitting air 
through the siren to the train pipe. 

When an engine is at a stand and remains thus for more than half 
an hour, the automatic battery switch operates and cuts the battery 
off from the cab apparatus, thus economising battery power. This 
battery switch is operated by the vacuum maintained in the engine 
reservoir or train pipe. When the vacuum is restored by the Engine- 
man the automatic switch pulls up and closes the battery circuit and 
energises the cab apparatus. 

In the event of a failure to pick up the electric current when a 
ramp is passed over, the effect on the engine apparatus is the same 
as though the ramp was not electrified, that is, the valve admitting 
air through the siren to the train pipe is opened, and the automatic 



Fig. 87 



186 



187 



brake is applied on the train, thus ensuring that any failure of the 
electrical apparatus shall produce the warning indications irrespec- 
tive of the position of the signals. 

EASTERN REGION, 
LONDON, TILBURY AND SOUTHEND SYSTEM 

Track Equipment 

Two magnets are fixed in the centre between the rails, 10-15 yd. 
apart and approximately 200 yd. on the approach side of a distant 
signal (or outer signal only when more than one is provided). The 
first contains a horizontal permanent magnet with its north pole at 
the trailing end and the second contains an electro-magnet. The 
electro-magnet is "dead" when the distant signal(s) is at Caution 
and "alive" with its south pole at the trailing end when the signal(s) 
has been pulled to Clear. The tops of the magnets are 1 in. above 
rail level. 

In addition to these, permanent magnets are provided in the outlet 
roads from sheds to test the equipment before going into service. 

Engine Equipment 

The equipment consists of a magnetic receiver, horn valve, 
vacuum horn, brake valve, re-setting magneto and indicator. 

The receiver is operated magnetically from the track magnets, its 
internal permanent magnet changing its position and operating an 
air valve as it passes over the north pole of the permanent magnet or 
the south pole of the electro-magnet. The re-setting magneto is 
provided to change it from the position taken up after passing a 
permanent magnet if the electro-magnet is "dead", as at a Caution 
signal. 

The admission of air through the valve in the receiver operates the 
horn valve which connects the horn to the vacuum reservoir and 
causes it to sound and admits air through a restriction to the timing 
reservoir and lower side of the brake valve. 

The upper side of the brake valve is connected to the train pipe so 
that the valve is normally balanced and kept closed by a spring. The 
admission of air to the under side upsets this balance and, after 
3 seconds, the valve opens to admit air to the train pipe, lowering 
its vacuum, and the valve assumes a new position of balance such 
that the fall in vacuum in the train pipe corresponds to the fall in 
vacuum in the timing reservoir. The fall of vacuum in this reservoir 
is calculated to reach 5 in. in about 15 seconds. 

This action occurs whenever the distant signal is at Caution and 








Fig. 88 



188 



189 



the receiver can be re-set to close the air valve by pulling the handle 
of the magneto. 

If the distant signal is at Clear and the electro-magnet "alive" 
this would be reached before the brake application started and the 
act of passing over the electro-magnet would close the air valve in 
the receiver to silence the horn. 

In addition to the audible signals of the horn a visual indicator is 
provided above the magneto. When a permanent magnet is passed 
the indicator turns to, or remains, black, but on pulling the handle 
of the magneto after passing the magnets at a Caution signal the 
indicator is turned to black and yellow. 

Summary of Indications Received 



Distant signal at 
Caution 



Distant signal at 
Clear 



Indicator black. 

Horn sounds. Brake application starts after 

3 seconds. Re-setting changes indicator to 

black and yellow. 
Indicator black. 
Horn sounds for short time. 

BRITISH RAILWAYS SYSTEM 



Track Equipment 

Two magnets are fixed centrally between the rails, 2 ft. 6 in. apart, 
generally 200 yd. on the approach side of a distant signal. The first 
contains a permanent magnet with its south pole uppermost and the 
second is an electro-magnet. The electro-magnet is "dead" when the 
distant signal is at Caution and "alive" with its north pole uppermost 
when the signal has been pulled to Clear. The tops of the magnets 
are at rail level. 

In addition to these, permanent magnets are provided in the outlet 
roads from the sheds to test the equipment before going into service. 

Engine Equipment 

The A.T.C. vacuum reservoir is exhausted from the ejector 
through a non-return valve and isolation cock which is sealed open. 
An electric switch operated by the vacuum connects the battery to 
the electrical circuits. The horn is connected to atmosphere through 
an electrically-operated valve in the Driver's control unit, and the 
under side of the brake valve and the timing reservoir are similarly 
connected to the vacuum reservoir. The upper side of the brake 
valve is connected to the train pipe. The brake valve is balanced by 
vacuum on both sides, but is kept closed by a spring. If air is 



• 




O 

cc 
h- 
Z 

o 

u 



< 
cc 

H 

U 

< 
Z 

o 

D 
< 



co 



00 



CO 



M* 



Fig. 89 



190 



191 



admitted to the under side of the valve, the balance is upset and the 
valve lifts to admit air to the train pipe. The brake valve is sealed 
open, but can be closed by a screwed plug in emergency. 

The receiver consists of a permanent magnet carrying contacts 
which act as a two-way switch, one contact being closed when the 
receiver has passed over a permanent magnet and the other contact 
being closed when the receiver has passed over an "alive" electro- 
magnet. 

When running normally the receiver contact closes a circuit to the 
electrically-operated valve in the Driver's control unit which controls 
the vacuum and air as described above. When the receiver passes 
over a permanent magnet the contact opens and after 1 second 
the solenoid is de-energised and the valve operates to connect the 
horn to the vacuum reservoir and cause it to blow and also to admit 
air through a restriction to the timing reservoir and brake valve. 
This occurs whenever the distant signal is at Caution. The brake 
valve opens to admit air to the train pipe and assumes a new position 
of balance such that the drop in vacuum in the train pipe corresponds 
to the drop in vacuum in the timing reservoir. The size of the 
restriction and capacity of the timing reservoir are calculated to 
reduce the vacuum to 5 in. in about 15 seconds. The horn can be 
silenced and the brake application cancelled by pulling the re-set 
handle, which re-sets the solenoid and restores the normal contact 
on the receiver. 

If the distant signal had been Clear the receiver would pass from 
the permanent magnet to the "alive" electro-magnet in less than 
1 second (when travelling at more than 2 m.p.h.). In this case the 
receiver contacts would change over as before on the permanent 
magnet and change back again on the electro-magnet. As less than 
1 second has elapsed the solenoid would not be de-energised to 
sound the horn or apply the brakes, but the changeover of receiver 
contacts picks up relays to ring the bell for 2 seconds. 

In addition to the audible signals of horn or bell a visual indicator 
is provided in the Driver's control unit. When the receiver passes 
over a permanent magnet, current passes to the indicator to turn it 
to, or keep it at, black. If the distant signal is at Caution and the 
re-set handle has to be pulled to silence the horn, the indicator 
changes to black and yellow. The indicator always continues to 
show the colour set up at one set of magnets until the next set is 
reached. 

Two points should be noted: 

(1) Pulling the re-set handle when not required to silence the 
horn will apply the brakes. 




(2) Pulling the re-set handle will only change the indicator 
from black to black and yellow after passing the magneto 
at a Caution signal. 

Summary of Indications Received 



Distant signal at 
Caution 



Distant signal at 
Clear 



Indicator black. 

Horn sounds after 1 second. Brake application 

starts after 3 seconds. Re-setting changes 

indicator to black and yellow. 
Indicator black. 
Bell rings for 2 seconds. 



Note. — On both the L.T. & S. Section and British Railways 
systems the complete magnet and housing which actuate the 
receiver on the locomotive is referred to as an "inductor". 



192 



SECTION 10 
THE RULE BOOK 

Rules are drawn up for the purpose of ensuring method and order 
in all movements and operations. 

method and order provide safety. 

We all know the story of the man who observed two trains 
approaching one another on the same line, his comment being that 
it seemed to him a funny way to run a railway! 

Railways are the safest means of transport. 

The Rule Book has been compiled on the basis of long experience 
and of common sense. Most of the rules have come into existence 
on the "case" method, that is, as the result of mishaps and of near- 
mishaps. 

If you find the Rule Book hard to digest you must apply the case 
method to your study. Visualise a station with which you are 
familiar, for instance, and imagine a derailed wagon blocking one 
line. What should be done to ensure protection of the line and how 
do the rules apply ? 

It is an axiom that it takes two people's mistakes to create a 
dangerous situation. Rules aim at preventing misunderstandings. 
Each man concerned has a definite duty laid down for him to 
perform. 

Any subject may be considered dull when studied in textbooks. 
Interest is aroused when your reading can be applied to real life 
and to real situations. Firstly, then, be prepared to visualise. 

Secondly, it is helpful to have a proper arrangement in one's 
mind of the various groups of rules. Sub-divided in this way the 
Rule Book will appear less formidable and the rules applying to 
one's particular calling, such as that of Enginemen, can be given 
special attention. 

We can proceed to divide the groups of rules as follows:— 

Rules 1 to 16 cover matters of discipline and procedure. Discipline 
implies a standard of behaviour which is essential to good order in 
any organisation. 

Rules 17 to 33 cover the working of stations. 

Rules 34 to 49 describe the various patterns of fixed or permanent 
signals. Their working and application are, of course, an important 
part of an Engineman's knowledge. 



193 



Rules 50 to 54 lay down the authorised hand signals. Hand 
signals must be properly given and properly interpreted to avoid 
misunderstandings. 

Rules 55 and 56 are very important safety rules, to ensure that a 
train standing on a running line is not forgotten. 

Rules 57 to 60 cover the use of detonators, which are a form of 
audible warning signal used where other methods of attracting a 
Driver's attention arc not practicable or need supplementing. A 
supply of detonators must be on every engine, with two red flags 
(see Rule 127). 

Rules 61 to 76, covering the working of points and signals, must 
be understood by Enginemen, as they have a joint responsibility in 
their correct operation. Note Nos. 69 and 70 (b), (c). 

Rules 77 to 80 refer to precautions imposed when signals are 
under repair, etc., and Rules 81 to 83 cover similar precautions 
when points and signals are defective. Certain paragraphs are 
directly applicable to Enginemen. 

Rules 84 to 95 ensure the running of trains in safety under the 
adverse weather conditions of fog and falling snow (see also the 
special instructions issued in a separate booklet to the staff). 

Rules 96 to 98 apply to the movements at stations. 

Rules 99 to 107 apply to the working of level crossings. 

Rules 108 to 118 cover shunting, where a thorough knowledge of 
hand signals is essential. Enginemen must observe certain pre- 
cautions when not accompanied by a Shunter. 

Rules 1 19 to 125 cover the use of lamps. Enginemen are respon- 
sible for headlamps and disc-boards and for tail-lamps when light 
engine. 

Rules 126 to 176 cover the normal working of trains. Nos. 126, 
127 and 128 are especially directed to Enginemen. Being train- 
operating rules, the whole of this group concerns Enginemen in 
their everyday duties. 

Rule 177. Reporting of Accidents. This rule introduces the 
section of the rule book dealing with abnormal occurrences and 
requires careful study. 



194 



195 



Rules 178 to 188. When the abnormal occurs, it is vital to 
preserve order in the face of emergency. Hence : — 

Rules 178 to 181 set out the system of protection. 

Rule 182 deals with "Trains divided." 

Rules 183 to 185 deal with the systematic removal of an 
obstruction. 

Rules 187 to 188 cover defects on a train. 

Rules 189 to 208 deal with the setting up of single-line working. 
Great care is necessary in this operation and Enginemen should 
note particularly Nos. 192, 196, 197, 202, 203, 204 and 206. 

Rules 209 to 239 cover the precautions to be taken when work is 
done on the line by the Civil Engineering staff. Enginemen must be 
familiar with Rule 216, Ballast Train Working, and Rules 217 and 
218 in regard to speed restrictions. 

Rule 240 should be studied, having in mind the fact that Engine- 
men, as well as others, are concerned with the conveyance of 
dangerous traffic. 

Certain of the rules are amplified by instructions in the General 
Appendix, which should be carefully studied. 



INDEX 

(NOTE: Typical questions and answers are placed at the 
end of each section — these are not covered in the Index.) 




Air brake, Westinghouse, 142 

Air, composition of, 23 

Air, primary and secondary, 25, 27 

Angle of advance, 85, 86, 103 

Anti-vacuum valves, 89 

Arch, brick, 46 

Ashpan, 17, 19 

Ashpan, hopper, 19, 46 

Atomiser, lubrication, 140 

Automatic Train Control systems:— 
Former G.W.R. system, 182, 183 
LT. & S. system, 182, 186 
B.R. system, 182, 188 

Automatic vacuum brake, 142 

Axleboxes, lubrication of, 129 

Axleboxes, roller bearing, 138 



Baffle plate, firehole, use of, 33 
Blast pipe, 44, 45 
Blowbacks, 31 
Blowdown valves, 69 
Blower valve, 53 

Boilers, mountings and details, 37 
Boilers, types of, 37 
Book, Rule, 192 
Brakes, 142 

Brakes, cylinder, vacuum, 161 
Brakes, graduable steam and vacuum, 

145, 149 
Brick arch, 46 
Bricks, broken, use of, 17 
B.R. Automatic Train Control 

System, 188 
British Thermal Unit (B.T.U.), 24, 34 



Cambox, HO 

Caprotti valve gear, 110, 115 

Carbon (see Combustion), 23, 25 

Carriage warming valve, 70 

Cleaners' duties, 16 

Coal, composition of, 23 

Coal, size of, 17, 32 

Combination lever, 103, 104 

Combustion, 23, 25 

Conduction, 34 

Convection, 35 

Crank, return, 103 

Cylinders, drain cocks, 89 

Cylinders, vacuum brake, 161 

Cylinders, Westinghouse brake, 173 



Dampers, use of, 33 
Defects, reporting of,. 18, 20 
Detonators, 17 
Diaphragm plates, 40 
Disposal duties, engine, 20 
Door, firehole, 46 
Door, mudhole, 53 
Drain cocks, cylinder, 19, 89 
Drivers' duties, 18 
Drop grates, 46 

Eccentric, 98 

Ejector, Dreadnought, 153, 157 

Ejector, vacuum, B.R. type, 

"S.S.J.", 143, 147 
Ejector, vacuum, G.W.R. types, 151 
Ejector, vacuum S.J. type, 159, 160 
Engine, disposal, 20 
Enginemen's duties, 17, 18 
Equipment, engine, 19 
Examinations, oral and practical, 16 
Exhaust injectors, 61 
Expansion link, 98, 103, 104 

Fire, preparing the, 28 

Firebox, 25 

Firebox, types of, 37 

Firehole, baffle plate, 33 

Firehole doors, 46 

Fire-irons, 17, 33 

Firemen, examinations, 16 

Firemen under control of driver, 22 

Firemen's duties, 17, 20, 28 

Firing, 26, 28, 29 

Firing, shunting locomotives, 32 

Foundation ring, 37 

Fusible plugs, 18, 52 

Gauges, pressure, 52 
Gauges, water, 18, 49, 51 
Gears, reversing, 115 
Gears, valve, 98 
Grates, drop, 46 
Grates, rocking, 46 
G.W.R. former, Automatic Train 
Control, 183 

Heat loss, 25 

Heat transfer, 34 

Heat, Unit of (B.T.U.), 24, 34 

Hopper ashpan, 19, 46 






196 



Injectors, exhaust, 61 
Injectors, failures, possible causes, 69 
Injectors, live steam, 57, 61 
Injectors, principles of, 56, 57 
Injectors, working of, 18, 33 



Lamps, 19 

Lap, 81, 88 

Lead, 81, 88, 101 

Locomotive, shunting, firing of, 32 

Locomotive, turning the, 21 

L.T. & S.— Auto. Train Control, 186 

Lubrication, 126 

Lubrication, axleboxes, 128, 129 

Lubrication, grease, 128 

Lubrication, hydrostatic, 131 

Lubrication, mechanical, 129 

Lubrication, methods of, 126 



Mechanical lubrication, 129 
Mudhole doors, 53 



Nitrogen, 25 
Notices, Permanent, 15 



Oxygen, 23 



Palm stays, 37 

Pipe, blast, 44 

Piston, 80, 88 

Piston valves, 86 

Plugs, fusible, 52 

Plugs, washout, 53 

Poppet, rotary cam, valve gear, 108 

Ports, steam exhaust, 80 

Preparing the fire, 17, 28 

Pressure gauge, 52 



Radiation, 35 

Radius rod, 103 

Regulator valve, double beat, 55 

Regulator valve, horizontal dome, 54 

Regulator valve, smokebox, 54 

Regulator valve, multiple, 56 

Regulator valve, slide, vertical, 53 

Repair Cards, 21 

Return crank, 103 

Rocking grate, 46 

Roller bearings, 138 

Rotary cam, poppet, valve gear, 108 

Rules, 15, 192 



Safety precautions, 19 

Safety valves, 48 

Saturated steam, 35 

Smoke, 28, 29 

Smokebox, self-cleaning, 40 

Stays, boiler, 37 

Steam heating apparatus, 18 

Stephenson valve gear, 98 

Sulphur, 25 

Superheated steam, 36 

Superheater, 40, 44 



Thermal unit, British (B.T.U.), 34 

Thermic Syphon, 40 

Train Control, Automatic, 182 

Train, starting away with the, 29 

Train working, 19 

Transfer, methods of heat, 34 

Triple valve, 166, 170 

Tubes, boiler, 37 

Turning the locomotive, 21 






NOTES 






Union link, 103 

Unit, British Thermal (B.T.U.), 34 

Vacuum brake, automatic, 142 

Vacuum ejector, 142, 151, 161 

Vacuum gauge, 142 

Vacuum pump, 151 

Valve gear, Bulleid, 86 

Valve gear, Grcslcy, 104 

Valve gear, rotary cam poppet, 108 

Valve gear, Stephenson, 98 

Valve gear, Walschaert's, 103 

Valves and pistons, 80 

Valves, anti-vacuum, 89 

Valves, auxiliary shuttle, 61 

Valves, blowdown, 69 

Valves, blower, 53 

Valves, carriage warming, 70 

Valves, events, 80 

Valves, regulator, 53 

Valves, safety, 48 

Valves, steam brake, 145 

Valves, steam controlled, exhaust 

steam, 61 
Valves, steam controlled, water, 65 
Volatile matter, 24, 27 






Walschaerts valve gear, 103 
Washout plugs, 53 
Water gauges, 18, 49, 51 
Water pick-up gear, 18 
Water valve, steam controlled, 65 
Westinghouse air brake, 142, 166 
Westinghouse brake cylinders, 173 
Whistle sounding, 19