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LOCOMOTIVE COMPOUNDING
AND SUPERHEATING.
H practical
FOR THE USE OF RAILWAY AND LOCOMOTIVE
ENGINEERS, STUDENTS, AND DRAUGHTSMEN.
BY
J. F. GAIRNS.
W
TOtb ^frontispiece an& H8 otber ^lustrations.
LONDON:
CHARLES GRIFFIN & COMPANY, LIMITED,
PHILADELPHIA : J. B. LIPPINCOTT COMPANY.
1907.
[All Rights Reserved.]
PREFACE.
IT is now just upon thirty years since the first practical compound
locomotives were built, but even yet the compound locomotive does
not occupy the universally accepted position which theory would
suggest that it should do. But whereas in the early years of its
existence as a definite feature of locomotive engineering practice it
was looked upon in most quarters with disfavour and distrust, and
the engineers first concerned with the design of such engines had to
contend against prejudice and opposition, and had no easy task to
obtain even a trial of their systems, now the position is far more
favourable, and compound locomotives according to many different
systems are to-day in use to the number of many thousands in various
parts of the world. In fact, it is not claiming too much to say that
the compound locomotive occupies to-day an assured position, and it
is probable that before many years have passed it will become a
standard feature of locomotive engineering in all countries.
As regards compounding for locomotives, Great Britain has main-
tained its reputation for conservatism, for its record in this respect is
not a very satisfactory one as compared with the experimental and
original work to be attributed to foreign locomotive engineers ; but
this is largely the result of different circumstances and policy.
In this country the Locomotive Superintendent or Chief Mechanical
Engineer of a railway is responsible for the design and efficiency of
large numbers of locomotives doing very hard and greatly varied
work ; but he is not encouraged to experiment or to depart radically
from standard methods : and in most cases he has to design engines
which are developments of previously existing designs, each class
being somewhat more powerful, more reliable, and yet more simply
and cheaply constructed proportionately than its predecessors. The
engines are also generally required to be capable of doing much work
for which they are not specially designed. Consequently, actual
novelties are few in British locomotive history, and notable experi-
ments and changes in methods of design occur only once or twice
during, it may be, a long term of service of a particular engineer as
locomotive chief. Individual originality of persons not occupying
principal positions has very little opportunity in this country, rightly
vii I
viii PREFACE.
so in view of the important interests at stake when a change of
engineering policy may entail the expenditure of many thousands of
pounds, probably with no satisfactory benefit, but unfortunately also
with the loss of much valuable experimental work, which, even if a
failure, may add greatly to engineering knowledge.
In the case of British locomotive building firms little scope is pro-
vided for original work on their part, though, as they deal with many
railways both at home and abroad, their experience and opportunities
are, in some ways, more extensive than in the case of the railway
officials ; but as a rule they are employed to build engines to designs
provided by the railway officials, and such an occurrence as the
building of an engine by the Vulcan Foundry Co., Ltd., to their own
designs, for the Great Northern Railway, in 1905, is very rare
indeed.
Abroad, however, the Chief Mechanical Engineers or Motive
Power Superintendents are in many cases responsible principally
for the maintenance and repair of locomotives, and the design of
new engines is largely the duty of superior engineers retained by
the railway, or of consulting engineers whose position is more
independent than our own Locomotive Superintendents, while the
various locomotive building firms are encouraged to introduce
novelties and to experiment in new directions, sometimes in
competition with one another ; their orders being, in many instances,
to provide engines which are capable of doing certain work with
the greatest efficiency, the builders having, in a large measure, a
free hand. As an example of this may be mentioned the official
competition instituted in Germany at the beginning of 1905, when a
number of locomotives designed wholly by individual firms, and in
several cases embodying radical departures from ordinary methods,
were officially tested, a number of similar engines being afterwards
ordered for regular service in two or three instances, though not all
the competing engines were successful.
On the other hand it must be remembered that Great Britain is
only a small country, without an extensive assortment of varying
circumstances and conditions of work, while Europe comprises many
countries of large area which provide almost every conceivable set
of conditions to be provided for by locomotive engineers. There is
therefore much greater justification for special and unusual loco-
motive design abroad than in Great Britain, where, generally
speaking, all requirements can be met by locomotives of selected
standard classes.
The foregoing remarks will, it is thought, go far to explain the
fact that, as regards the compound use of steam for locomotives, three
or four names only can be mentioned as of special note among
British engineers in this respect, whereas thirty or forty engineers
and firms require corresponding mention in connection with Conti-
nental and American practice, while, as regards the use of superheated
steam, the credit must almost entirely be divided between German,
Canadian, American, and Belgian engineers.
PREFACE. ix
Having thus provided some explanation of the fact that in this
work about 80 per cent, of the matter included relates to the work
of foreign engineers, a few notes regarding the scheme followed by
the writer in its preparation will be in place.
The subject of compounding for locomotives has received frequent
attention in the technical press of this and other countries, articles
in some cases being fairly comprehensive within their scope, and
containing much valuable information as regards technical and
theoretical matters ; but, so far as the present writer is aware, only
three really technical publications may be considered as being
properly indicative of the world's practice. These are:
(1) The late Professor Wood's book on Compound Locomotives,
published in the United States in 1892-3.
(2) Mons. Edouard Sauvage's articles, which appeared in 1897 in
La Revue des Mecaniques.
(3) Herr E. Briickmann's paper, which appeared in 1896 in Der
Zeitschrift des Vereines deutscher Ingenieure.
As will be seen, none of these are sufficiently up to date to cover
recent practice, and although Mons. Sauvage has to some extent
noted later development by many contributions to the French
Engineering Press, and by papers presented to our own Institution
of Mechanical Engineers, it is correct to state that no approximately
thorough review of locomotive compounding has ever been published
in this country, nor has any work of this kind been published for
many years in any country.
To provide a substantially complete and systematic work on this
subject has been the object of the writer, who, in addition to his
own very considerable knowledge of the world's locomotive practice,
has been favoured with private information from locomotive engineers
and locomotive building firms. Articles which have appeared in
technical magazines and journals, as well as papers read before
engineering societies, have also been carefully considered, and general
acknowledgment is hereby made of such assistance. Specific
reference is gratefully made to the following gentlemen, firms, and
journals in particular :
(a) Messrs A. Mallet, A. G. de Glehn, C. Baudry, G. du Bousqiiet,
Walter M. Smith, S. M. Vauclain, F. J. Cole, the late A. von Borries,
K. von Golsdorf, A. Lindner, A. Brunner, etc.
(b) The firms of Alsatian Works, Hanover Engine Works, Saxon
Engine Works, Baldwin Locomotive Works, American Locomotive
Co., Rogers Locomotive Works, A. Borsig, J. A. Maffei, C.
Breda, etc.
(c) The chief engineers of the French State, Eastern and
Southern Railways, and of the Hungarian and Swedish State
Railways, etc.
(d) The Proceedings of the Institutions of Mechanical and Civil
Engineers, the American Master Mechanics' Association, the French
Institution of Civil Engineers, The Engineer, Engineering, La Revue
Generate des Chemins de Fer, Railroad Gazette, Locomotive Magazine^
X PREFACE.
and Cassier's Magazine. In the latter case, some extracts are included
from the writer's own articles in that magazine.
In a few instances where the illustrations are reproduced directly
from the publications named, acknowledgment is specially made.
As a rule, however, the illustrations are merely adapted where
private drawings were not available. The photographs reproduced
are all from official sources.
Acknowledgment must also be made of the loan of several blocks
by the Baldwin Works and the American Locomotive Company.
The author has not devoted much space to the theoretical and
highly technical aspects of locomotive compounding and superheating,
partly because the late Professor Wood has provided a work of this
character which can never be quite out of date^ in this respect, but
principally because it seemed preferable to present a review of
practice and methods of applying compounding and superheating to
locomotives, together with a general consideration of the peculiar
problems which complicate these subjects as applied to locomotive
engineering as compared with compounding and superheating for
other steam engines. Consequently the early portion of this book
contains only a glossary of terms, an introductory chapter, a chapter
dealing with the special conditions governing the application of
compounding and superheating to locomotives, a chapter on the
classification of compounding systems, and a brief historical chapter,
the remaining chapters being devoted to special divisions of our
subjects and dealing with past and present practice, though some
argumentative and technical matter is included.
As regards the use of superheated steam for locomotives, the
subject is of such recent importance that a collection of matter
relating to the various apparatus in use has not hitherto been
presented in any technical book on the locomotive engine, and this
work provides a convenient and suitable opportunity for presenting
a general review of this branch of locomotive engineering.
J. F. GAIRNS.
LONDON, Jan. 1907.
OF THE
UNIVERSITY
OF
CONTENTS.
CHAPTER I.
INTRODUCTORY.
The Compound Use of Steam The Objects of Compounding Two-stage
Expansion versus One-stage Expansion Division of Work between
two Cylinders Cylinder Condensation and Re-evaporation Cylinder
Heating and Cooling Uniformity of Thrust and Pull transmitted
through Piston Rod The Use of Superheated Steam in Engines The
Objects of Superheating ......... 1
CHAPTER II.
THE COMPOUND USE OF STEAM FOR LOCOMOTIVE ENGINES.
General Remarks Comparison of Locomotive and other Steam Engines
as regards Compounding Reasons for and against Compounding for
Locomotives Adaptation of Locomotive Engines for greatly varying
Conditions of Work Direct and Indirect Economy due to Com-
pounding - Mechanical Advantages obtained by Compounding
Additional First Cost and Complication The Influence of Com-
pounding on the Fireman's Work .......
CHAPTER III.
A CLASSIFICATION OF COMPOUND SYSTEMS.
Principal Features of Classification Cylinder Arrangements for (1) Two-
cylinder Systems ; (2) Three-cylinder Systems ; (3) Four-cylinder
Four-crank Systems ; (4) Four-cylinder Two-crank Systems ; (5)
Tandem Systems; (6) Articulated Engines Cylinder Ratios-
Receivers and Receiver Capacities Arrangement of Cranks, Division
of Power, Balancing Valves, Valve Gears, Independent Adjusta-
bility of Valve Gears for High- and Low-Pressure Cylinders,
Character of Steam Distribution Starting and Intercepting Valves 15
Xll CONTENTS.
CHAPTER IV.
THE HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE.
PAGE
The earliest Suggestions The Nicholson-Samuel "Continuous-Expan-
sion " System The Sutcliffe and Salmon Proposals E. Kemp's
Tandem Single-acting System Joy's Four-cylinder Suggestion
Morandiere's suggested Three-cylinder Engine Weir's Three-
cylinder System Fairlie Double-bogie Type Dawes' suggested
Four-cylinder Arrangements Hudson's proposed Arrangement-
Mallet's first Engines Andrade's Three-cylinder Design Holt's
Designs for Compound Tramway Engines The Struwe Three-
cylinder Design Mallet's suggested Schemes Von Berries' first
Engines Worsdell's first Engines Webb's first Three-cylinder
Engines Sandiford's Experiments in India The Du Bousquet
Tandem System in France The Dunbar Tandem System The
Nisbet and Great Western Tandem Experiments Mallet's Articu-
lated System Brief Review to Date 28
CHAPTER V.
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
The Mallet System Worsdell-von Borries-Lapage Non-automatic System
Batchellor System Colvin System Worsdell-von Borries-Lapage
latest System Landsee Asynometric System Mallet Two-cylinder
Tandem System Brunner System Starting Arrangements on
Eastern Railway of France Rogers Non-automatic System Two-
cylinder Compound Locomotives (Non-automatic) on the Hungarian
State Railway Schenectady Non-automatic System Vauclain Two-
cylinder System The Cooke System Nadal System The Dultz
System Two-cylinder Compound Engines in Italy .... 42
CHAPTER VI.
TWO-CYLINDER AUTOMATIC SYSTEMS.
The Worsdell-von Borries-Lapage Systems Mr Worsdell's Practice
Herr von Berries' Practice Joint Practice Automatic Starting and
Reducing Valves for Hungarian State Railway Systems The
Schenectady (Pitkin) System The Vauclain Automatic System
The Dean System The Player System The Rogers Automatic
System ............ 67
CHAPTER VII.
SEMI-AUTOMATIC SYSTEMS (LINDNER TYPE).
The Lindner System Modifications of the Lindner System The Maft'ei
System Two-cylinder Swiss System The Cooke Starting Mechanism
Golsdorf System 83
CONTENTS. xiii
CHAPTER VIII.
THREE-CYLINDER COMPOUND SYSTEMS.
PAQK
General Remarks Methods of Compounding with Three Cylinders
Webb Three- cylinder System for Passenger and Tank Engines The
Webb System as applied to Goods Engines The Riekie Three-
cylinder System The Sauvage System The Swiss System^The
Smith System 91
CHAPTER IX.
FOUR-CYLINDER TWO-CRANK SYSTEMS (TANDEM CLASS).
General Remarks The Du Bousquet "Woolf" System The Brooks
System The Vauclain Tandem System The American Locomotive
Company's System The Sondermann System Mallet Tandem
System in Russia Tandem Compounds for Hungarian State Rail-
waysThe new Du Bousquet Tandem System . . . . . 101
CHAPTER X.
FOUR-CYLINDER TWO-CRANK SYSTEMS (OTHER THAN TANDEM).
The Vauclain Superposed Cylinder System The Johnstone Annular
Cylinder System 114
CHAPTER XI.
FOUR-CYLINDER BALANCED SYSTEMS.
Introductory Remarks The Webb Four-cylinder System The Golsdorf
Four-cylinder System Four-cylinder Italian System Smith Four-
cylinder System Von Borries Four-cylinder System Maffei
Compound Engines Compound Locomotives on the Lancashire
and Yorkshire Railway Balanced Compound Locomotives on the
Hungarian State Railways 122
CHAPTER XII.
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
General Remarks The de Glehn System Vulcan Foundry Engine (de
Glehn System) for Great Northern Railway De Glehn Compound
Engines for Portuguese Railways, built by A. Borsig The Henri-
Baudry System The Vauclain Balanced System The Cole System
Ivatt's Compound Engine for Great Northern Railway Compound
Engines in Belgium . . ... . ... 131
Xiv CONTENTS.
CHAPTER XIII.
ARTICULATED COMPOUND ENGINES.
PAGE
Articulated Engines The Mallet System Mallet Compound Engines for
St Gothard Railway Mallet Compound Engines for Russia Mallet
Compound Engines in the United States The Meyer-Lindner
System Compound Fairlie Engines The Johnstone Articulated
Engine The Du Bousquet Articulated System .... 148
CHAPTER XIV.
TRIPLE EXPANSION LOCOMOTIVES COMPOUND RACK RAILWAY
LOCOMOTIVES CONCLUDING REMARKS CONCERNING COM-
POUND LOCOMOTIVES.
Mallet's Triple-expansion Engine Riekie's Triple-expansion Scheme
Compound Rack Locomotives with Four and Six Cylinders Con-
cluding Remarks concerning Compound Locomotives The Future
of Compounding for Locomotives 159
CHAPTER XV.
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES.
General Remarks The Advantages and Economy of Superheating for
Locomotives A short History of the Schmidt Superheater as applied
to Locomotives The Schmidt Superheater, Smokebox Type The
Schmidt Superheater, Smoketube Type Schmidt Superheaters in
Belgium The Pielock Superheater The Cole Superheater Super-
heating Apparatus on the Lancashire and Yorkshire Railway The
Cockerill Superheater The New Century Engine Company's System
Superheating Apparatus in New Zealand . . . . . 1 63
INDEX 187
LIST OF ILLUSTRATIONS.
FIG.
1. Two-cylinder System Inside Cylinders,
2. ,, ,, Outside ,,
3. Three-cylinder System (1 H.P. and 2 UP.),
4.
5. Webb Three-cylinder System, .
6. Three-cylinder System (2 H.P. and 1 L.P.),
7. Four-cylinder Balanced System,
9
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
to 12. Four-cylinder Divided and Balanced System, . . .
Tandem Cylinders,
,j ,, ..........
Tandem Cylinders with Three Piston Rods, . . . . ' .
Superposed Cylinders Vauclain System, . . ...
Johnstone Annular System, . . ...
Articulated Compound System, . . . . . . .
Nicholson- Samuel System (1850),
Single-acting Four-cylinder Scheme (1860), . . .
Morandiere Three-cylinder System (1866), . . .
Four-cylinder Tandem System (1872)
,, Four-crank System (1872), . .
,, System Oscillating Cylinders, . . . . .
Mallet Compound Locomotive View of, . . ...
,, ,, ,, Cross-section, ..... . .
Proposed Three-cylinder System (1879), . . .
First von Berries Two-cylinder Compound Engine (1880), .
Worsdell Two-cylinder Compound Engine (1884), . ' . .
First Webb Three-cylinder Compound Engine, .
Mallet Articulated Compound Engine, ......
One Form of Mallet Intercepting Valve,
Worsdell- von Borries-Lapage Non-automatic Starting and Intercepting
Valve,
Rhode Island (Batchellor) System General Arrangement, .
}J ,, ,, Intercepting Valve,
Mellin Starting and Intercepting Valve,
Colvin ,, ,,
PAGE
17
17
17
18
18
19
19
19
20, 21
21
21
21
22
22
22
22
30
31
31
32
33
33
34
35
36
37
37
39
40
43
44
46
46
48
48
XVI
LIST OF ILLUSTRATIONS.
FIG.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
Worsdell - von Borries - Lapage Improved Non- automatic Starting
Valve, 49
Mallet- Brunner Tandem System, . . 51
Starting Mechanism for Brunner System, 52
Rogers Non-automatic Starting Mechanism, 54
Hungarian State Railways Non-automatic Starting and Intercepting
Valve, 55
New Schenectady Starting and Intercepting Valves, . . . . 57
M Non-automatic System General Arrangement, . 58
Vauclain Two-cylinder System Position of Valves when working
Single Expansion, . .59
Vauclain Two-cylinder System Position of Valves when working
Compound, 59
Vauclain Two-cylinder System Cylinder and Smoke-box Arrangement,
Cooke Starting and Intercepting Valve Compound Position, . - .
,, ,, Non-compound Position,
Nadal System High-pressure Cylinder and Connections, .
,, ,, Low-pressure ,, ,, ...
,, ,, General Arrangement,
Dultz Starting and Intercepting Valve, 66
Worsdell System General Arrangement first employed, ...
,, Starting and Intercepting Valve (early Form),
Von Borries System Starting and Intercepting Valve (early Form), .
j> > t> >
,, ,, Further Construction of Valve,
Worsdell-von Borries -Lapage System recent Design of Starting and
Intercepting Valve,
Hungarian State Railways General Arrangement of Starting Mechanism,
60
61
62
63
64
65
Intercepting Valve, .
Starting Valve,
, , Mechanism,
Driver's Starting Valve,
Intercepting Valve, .
Schenectady System Early Form of Starting and Intercepting Valves,
Vauclain (Baldwin Works) Automatic System,
Dean Starting and Intercepting Valves, ......
Player System (Brooks Locomotive Works) Starting and Intercepting
Valves,
Rogers Locomotive Works (Automatic) System,
,, Detail View,
Lindner System Regulator and Starting Valve (original Design),
,, ,, Slide Valve and Steam Ports, .....
,, ,, Starting Mechanism (Improved Form), .
,, - ,, (modified), Diagrammatic Arrangement, .
Maft'ei System Starting Mechanism
,, ,, Detail of Mechanism,
Golsdorf System Slide Valve and Auxiliary Steam Ports, .
J> ) >l 5 ...
,, General Arrangement,
68
68
69
70
71
71
72
73
74
74
76
77
77
77
78
78
79
80
81
82
84
85
86
87
88
89
89
90
90
LIST OF ILLUSTRATIONS. XV11
FIG. PAGE
84. Smith Three-cylinder System Starting Valve, .... 98
85. ,, ,, ,, Pressure- regulating Valve, . . 99
86. ,, ,, ,, General Arrangement, . . . 100
87. Du Bousquet (Woolf) Tandem System, 102
88. ,, Starting Mechanism, . . 103
89. Player Tandem System (Brooks Locomotive Works) Section of
Cylinders and Slide Valves, 104
90. Player Tandem System (Brooks Locomotive Works) Starting
Mechanism, 105
91. Vauclain Tandem Compound System Section of Cylinders, . . 106
92. American Locomotive Company's System Section of Tandem
Cylinders, . . . . 107
93. American Locomotive Company's System Starting Valve, . . 108
94. Sondermann System Section of Cylinders, . . . . . 110
95. Mallet Tandem System Section of Cylinders, . ... . 110
96. Hungarian State Railways Section of Tandem Cylinders, . . Ill
97. Du Bousquet (New) Tandem System Starting Mechanism, . . 112
98. Vauclain Compound Compressed-air Mine Locomotive, . . . 115
99. ,, ,, Locomotive Front View, .... 116
100. 101. Vauclain Compound System Cylinder Castings, . . . 117
102. ,, ,, ,, Cylinders and Fittings, . . 117
103. Vauclain Four-cylinder Compound System Steam Distribution, . 118
104. ,, Compound System- Starting Valve, . . . . 119
105. 106. Starting Cock for Vauclain Compound System, . . . 120
107. Modified Starting Valve for Vauclain Compound System, . . 120
108. Johnstone Annular System Section of Cylinders, . . .. . 121
109. Webb Four-cylinder System Slide Valves, ...... 123
110. Golsdorf Four-cylinder System Cross- section, .... 125
111. Italian Four-cylinder Compound System Cylinders and Valve
Chests, 126
112. Von Borries Four-cylinder System Valve Chests and Starting
Valves, 128
113. Maffei Four-cylinder Compound Locomotive Cross -section, . . 129
114. De Glehn Four-cylinder Compound Express Locomotive Cross-
section; . 132
115. De Glehn Four-cylinder Compound Express Locomotive Sectional
Plan, . . , . 133
116. De Glehn Compound System Diagram of, . . . . 135
117. ,, Intercepting Valve Detail View, . . . .136
118. ,, System Eastern Railway of France, ... 137
119. .... 138
120. ,, Intercepting Valve and Operating Mechanism (Borsig), .
121. Vauclain Balanced System Cylinder and Valve Castings, . . 140
122. Steam Distribution in Balanced Compound Cylinders, ... 141
123. Vauclain Divided and Balanced System Cylinders and Motion, . 142
124. Cole System Divided and Balanced Compound System, ... 144
125. Belgian State Railways Diagrammatic Plan of Balanced Compound
Locomotive, ,...... 1^6
126. Belgian State Railways Diagrammatic Plan of Divided and
Balanced Engine, . . . . . . 147
127. Mallet Articulated Compound Engines Comparison, . . . 150
xviii LIST OF ILLUSTRATIONS.
M . PAGE
128. Mallet Articulated Locomotive Moscow- Kazan Railway, . . 153
129. ,, ,, Cross-section through H. P. Cylinders, 154
130. ,, L.P. ,, 155
131. Johnstone Annular System Mechanism for Annular Compound
Double Locomotive, 156
132. Articulated Tank Engine Northern Railway of France, . . . 157
133. Mallet's Suggested Design for Triple Expansion Locomotive, . . 160
134. Riekie's Proposed ,, ,, ,, 160
135. Compound Hack Locomotives, 161
136. Schmidt Superheater Smoke-box Type, 167
137. ,, Smoke-tube Type 171
138. Pielock Superheater, . . ... . . . , . 174
139. ,, detached, 175
140. ,, ,, detached from Boiler, and showing Boiler Tubes, 176
141. Cole Superheater Smoke-box Arrangement, 178
142. .179
143. ,, System Closed Ends of Superheater, 180
144. ,, ,, Modified Arrangement of Superheater, . . . 180
145. Experimental Superheating Apparatus ; fitted by John Cockerill
Company Belgian State Railways, . . . . . . 182
146-148. New Century Engine Company's Steam and Compressed Air
System, 184, 185
GLOSSARY OF TERMS.
MOST of the technical terms which will be used in this book are common to all
branches of steam engineering, and are fully explained in any text-book dealing
with steam and the steam engine ; but for the benefit of general readers and for
completeness, this glossary of terms is presented in introduction, the explanations
being couched in some cases in language particularly appropriate to the subjects
under consideration. As a rule, the glossary is based upon that provided in
Professor Wood's book referred to in the Preface, though amplified. Only the
most important terms are, however, included, terms which explain themselves
being generally omitted.
Back Pressure. In a compound engine, as the steam from the exhaust side
of the high-pressure piston passes to the steam side of the low-pressure piston it
exerts pressure for a time in two directions, for while it tends to force the low-
pressure piston forwards, it also tends to force the high-pressure piston backwards
against the pressure of steam on the steam side. This backward pressure is
generally referred to as "back pressure"; and while the two cylinders are in
communication, the actual work being done in the high-pressure cylinder is only
the difference between that done on one side of the piston by the boiler steam and
that on the other side by the low-pressure steam.
The term is also used generally to indicate any pressure which acts oppositely
to the steam pressure, due to the ' ' choking " of the exhaust steam in consequence
of the ports or passages through which it escapes being restricted, or from other
causes.
By- Pass Valve. A valve which, when opened, allows communication through
a pipe or passage between the two ends of a cylinder.
Compound Engine. An engine wherein the steam is used in one cylinder for one
stage of expansion, and is then passed to a second cylinder for a second stage of
expansion. Strictly, there are only two stages of expansion in a compound engine,
though the term is sometimes used loosely to describe any engine wherein ex-
pansion is carried out in stages. Properly speaking, however, three-stage ex-
pansion engines should be described as "triple-expansion engines," four stage
engines as "quadruple-expansion engines," and so on.
Compounding. This term is employed to describe the general principle of
expansion by stages, whether in two, three, four, or more stages.
Continuous Expansion. In many cases steam cannot be passed directly from
one cylinder to the other in a compound engine, owing to the fact that the pistons
of the respective cylinders do not reach the ends of their strokes at the same
time ; but in other cases they do so, and the steam can therefore pass from one
cylinder to the other unchecked. The term "continuous expansion" is some-
times used to describe the latter method of working, but it is not very generally
employed. An example of its use in another connection is given in Chapter IV.
Cut-off. The point where the admission of steam to a cylinder is cut off. It is
XX GLOSSARY OF TERMS.
generally expressed at so much per cent., or as a fraction of the stroke, though
occasionally, where the length of stroke is known, it is stated as so many
inches. For example, if the stroke is 24 inches and steam is admitted for a
quarter of the stroke, the ratio of cut-off may be expressed as "25 per cent.," or
"at quarter-stroke (|)," or "at 6 inches," the first of these is, however, most
general, unless the cut-off can be expressed by a simple fraction, as "quarter-
stroke," "one-third stroke," etc.
Cylinder Condensation. The condensation or deposition of moisture that is
suspended in the steam owing to the fall in pressure and temperature of the steam,
or in consequence of contact of the steam with the cylinder walls when they are
colder than the steam.
Cylinder Re-evaporation. The re- evaporation of condensed water resulting
from cylinder condensation in a cylinder on the entrance of a fresh steam supply
from which the necessary heat is extracted for the purpose.
Exhaust Pressure. The pressure at which the steam, after use, leaves a
cylinder, either to pass away to the atmosphere or a condenser, or to another
cylinder for compound working.
Expansion. The increase in volume of steam enclosed in a cylinder after cut-
off. As the steam expands, it forces the piston along, increasing in volume and
losing pressure as it does so.
Final Pressure. The pressure of the steam when exhausted from the low-
pressure or last cylinder in compound working.
High-Pressure Cylinder. The cylinder in which the first stage of expansion is
carried out in compounding. In this work the abbreviation " H.P. cylinder"
will often be employed.
Initial Pressure. The pressure of steam at the beginning of a stroke. In
connection with compounding, the term is often used to indicate the pressure at
which steam is admitted to the high-pressure cylinder, in contrast to " terminal"
or final pressure, which indicates the pressure at which steam is finally exhausted
from the last or low-pressure cylinder of a series of cylinders.
Indicator Diagram. The diagram obtained by means of an instrument known
as an "indicator," whereby the variation of steam pressure in the cylinder
throughout a stroke is indicated in the form of a curve, from which the amount
of work being done can be computed.
Intercepting Valve. A valve whereby communication may be closed between
the respective cylinders of a compound or multiple -expansion engine when re-
quired, so that the cylinders can be operated independently with boiler steam, as
at starting in the case of a compound locomotive engine, or for the temporary
exertion of very great power. In many cases the intercepting valve also governs
a passage whereby the exhaust steam from the high-pressure cylinder or cylinders
of a compound locomotive can pass to the chimney when boiler steam is being
used in the low-pressure cylinder or cylinders.
Intercepting valves are constructed in many different forms, but they can all
be classed as "automatic" or "non-automatic." In the former case they are
operated or moved from one position to the other according to which side the
steam exerts the greatest pressure ; in the latter case they require to be mechani-
cally operated.
Intermediate Cylinder. In triple-, quadruple-, or other multiple-expansion
engines, the first and last cylinders are referred to as high- and low-pressure
cylinders, the cylinder or cylinders between being known as the intermediate
cylinder or cylinders, or as the first, second, etc. intermediate cylinders when
there are two or more of them.
Low- Pressure Cylinder. The cylinder in which the last stage of expansion
is carried out in compounding. In this work the abbreviation " L.P. cylinder "
will often be employed.
Multiple Expansion. Expansion in more than two stages, as in a triple- or
quadruple-expansion engine.
Mean Pressure. The average pressure of steam which is exerted in an engine
cylinder during a stroke.
Non-compound Engines. Engines wherein steam is expanded in one stage only,
compounding not being employed.
GLOSSARY OF TERMS. XXI
Non-Receiver Engines. Engines for which no receiver or steam-storage chamber
is employed between high- and low-pressure cylinders, the steam passing directly
from one cylinder to the other. The term is to some extent synonymous with
" continuous expansion."
Ratio of Cylinders. The relative proportions of the volumes of the respective
cylinders of a compound or multiple-expansion engine.
Ratio of Expansion. The ratio which the admission pressure of steam bears
to the exhaust pressure in one cylinder, or which initial pressure bears to final
pressure in a compound or multiple-expansion engine.
Receiver. The chamber or space wherein steam is contained before passing
from one cylinder to the next in a compound or multiple-expansion effgine. The
term is generally used to describe a chamber or length of piping specially
provided in order to receive steam from one cylinder when it is not able to pass
at once to the next cylinder.
Receiver Engine. A compound or multiple-expansion engine having one (or
more) receivers.
Re-evaporation. See "Cylinder Re- evaporation."
Saturated Steam. Steam as generated in contact with water, as in a boiler,
so that it holds water in suspension, wet steam. Under ordinary conditions all
steam is saturated steam.
Sequence of Cranks. The order in which the cranks of the respective cylinders
of an engine follow one another in rotation.
Simple Expansion. The same as non-compound.
Single Expansion. The same as non-compound.
Superheating. The heating of steam after generation for the purpose of
evaporating moisture contained there and for increasing its temperature and
volume.
Tandem Compound Engine. An engine wherein cylinders are placed one
behind the other, the respective pistons being mounted on the same piston rod,
or in an equivalent manner.
Terminal Pressure. The same as "final pressure."
Total Expansion. The ratio between initial steam pressure and the terminal
or final pressure in a compound or multiple-expansion engine.
Wet Steam. See "Saturated Steam."
Wiredrawing. The throttling of steam through a small aperture ; a reduction
of pressure by restricting the flow of steam.
LOCOMOTIVE COMPOUNDING
AND SUPERHEATING.
CHAPTER I.
INTRODUCTORY.
CONTENTS : The Compound Use of Steam The Objects of Compounding Two-
stage Expansion versus One-stage Expansion Division of Work between
two Cylinders Cylinder Condensation and Re-evaporation Cylinder Heat-
ing and Cooling Uniformity of Thrust and Pull transmitted through. Piston
Rod The Use of Superheated Steam in Engines The Objects of Superheating.
The Compound Use of Steam. The compound use of steam in
steam engines has been known for more than a hundred years, and
it has been a standard feature of steam engineering, except for
locomotive engines, for at least forty or fifty years, while it is now
almost universal for large marine and stationary engines.
The Objects of Compounding. The objects of compounding are
(1) To enable the power represented by the steam generated under
pressure to be applied in such a manner that full advantage can
be obtained from expansion without incurring the disadvantages
which become serious if too great an expansion is attempted in one
cylinder.
(2) To allow of a greater range of expansion being utilised than
is practically possible by non-compound methods, and so to more
efficiently and economically use the steam before it is discharged.
(3) To maintain a more uniform pull or thrust upon the piston
rod throughout the stroke than is possible when steam is cut off
early in the stroke in a non-compound engine.
(4) To obtain mechanical advantages by the use of a multiplicity
of cylinders without imposing additional strain upon the boiler.
(5) To allow of high-pressure steam being used with full advantage.
Unless extended expansion can be carried out, the higher the initial
pressure, the higher will be the exhaust pressure, so that part of the
gain due to the use of high-pressure steam cannot be fully realised
unless compounding is resorted to.
Two-stage Expansion versus One-stage Expansion. Division of
Work between two Cylinders. These objects are attained by using
1
2 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
the steam in stages, first in one cylinder, where it does a certain
amount of work, and then in another cylinder, or two or more
cylinders successively, where it does further work before it is finally
passed away to the atmosphere through the chimney, or to a condenser.
In a steam engine cylinder the steam is admitted for part of the
stroke only, and the steam supply is then cut off, the steam working
during the remainder of the stroke by expansion, though as it
expands it loses pressure, owing to the fact that it occupies a
gradually increasing space. Thus, for example, steam at 180 pounds
per square inch may be admitted for one-third of the stroke, after
which it is allowed to expand, doing further work, but of gradually
lessening amount, until it is permitted to "exhaust" at a pressure
of, say, 80 pounds per square inch.
It is bad practice to allow steam to pass away at a pressure which
indicates that there is still much working power remaining, and to
exhaust at 80 pounds per square inch is clearly wasteful ; it is
therefore desirable that as much of the expansive power of the
steam shall be utilised as possible.
Theoretically, this can be done in one stage by cutting off very
early in the stroke, say at 5 per cent., so that the steam pressure
may fall from admission at 180 pounds per square inch to exhaust
at 10 pounds or less ; but in practice this becomes well-nigh impossible
because of other considerations, and for that reason the work is
best divided over two (or more) cylinders, thus constituting a
compound engine.
Cylinder Condensation and Re-evaporation. Cylinder Heating
and Cooling. Of these considerations, the principal is "cylinder
condensation." This occurs owing to the fact that as the pressure
falls the temperature falls also ; and as boiler steam always contains
a considerable amount of suspended moisture, while its capacity for
holding such moisture decreases with the temperature, it follows
that not only do the cylinder walls become cooler to a greater or
less extent by the time a stroke has been completed, but some of
the suspended moisture becomes deposited as water. When a second
supply of steam is admitted to the cylinder for the next working
stroke, it meets the cylinder walls, whose temperature is less than
that of the entering steam, and an interchange of heat units takes
place to equalise matters. This causes the steam to lose some of its
heat, and therefore to lose some of its pressure, before it can do
any useful work, and a certain amount of its moisture is deposited.
But this moisture, together with that remaining from the previous
stroke, requires to be evaporated before work can be commenced,
and there is a further loss of heat and pressure, so that some of the
gain due to expansive working is negatived, owing to the cylinder
walls being alternately heated and comparatively cooled, and the
condensation and re-evaporation of the deposited moisture.
The cooling and reheating of cylinder walls, and cylinder con-
densation and re-evaporation, must always occur, though, by using
superheated steam, or by providing the cylinder with a jacket in
INTRODUCTORY. 3
which steam or furnace gases circulate, these results are lessened ;
if, however, an extensive range of expansion is attempted, these
effects become serious, and there is therefore a practical limit to
the cut-off ratio that can be satisfactorily employed. It will be
seen, then, that by ordinary methods it is not possible to utilise all
the work contained in the steam.
Another result attending early cut-off is a want of uniformity in
the thrust or pull transmitted through the piston rod owing to the
fact that there is great difference between the steam pressure at
the commencement of the stroke and that at the end of the stroke.
There are also other difficulties, such as the necessity for a special
valve gear, whereby satisfactory steam distribution can be obtained
at all times whether the cut-off is late or early.
Uniformity of Thrust and Pull. By compounding, however, the
work is distributed, the steam being use<l first in one cylinder
with a late or reasonable cut-off, where it works under satisfactory
conditions with limited cylinder condensation, and giving a fairly
uniform thrust or pull upon the piston rod ; it is then passed to
another cylinder, or to two or more cylinders in series, where
further work is done under satisfactory conditions.
As a result, steam can be expanded to a degree that is impossible
when all the work has to be done in one cylinder, and this is
effected without the incidental disadvantages of one-stage expansion
with an early cut-off.
Another possibility which is sometimes very valuable is due to
the fact that as more than one cylinder is necessarily employed,
more driving impulses per revolution can often be obtained,
although, were this attempted by merely multiplying cylinders, it
would be difficult to maintain sufficient steam supply therefor
without introducing extravagant methods of working.
It will therefore be seen that compounding is desirable for all
steam engines, and is practically a necessity when high steam
pressures are employed if economy is to be obtained ; and this fact
is appreciated in marine and stationary steam engineering, in
connection with which it is well-nigh universal ; but when its
employment for locomotive engines is in question, although there
is no doubt whatever as to its desirability, other considerations
complicate matters to a great extent, as will be set forth in the
next chapter.
The Use of Superheated Steam in Engines constitutes a means
for obtaining nearly the same objects as those achieved by com-
pounding, but it differs therefrom principally in that by this
method of working extended expansion can be carried out in one
cylinder, though in some cases superheating is used in connection
with compounding.
Objects of Superheating. In superheating, the steam is heated
in a chamber or in passing through tubes exposed to the effect of
4 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
furnace gases (usually the waste gases from the boiler furnace, so
that heat is utilised that would otherwise be wasted), whereby its
temperature is raised above that proportionate to the pressure at
which it is generated (its volume also becomes increased to some
extent) ; and the moisture suspended in the boiler steam (generally
referred to as " saturated " steam) becomes evaporated, so that the
effects of cylinder condensation are minimised, and there is a reserve
of heat available for reheating the cooled cylinder walls as steam is
admitted to the cylinder, and for re-evaporating water of condensation
if any is present in the cylinder. By its use, therefore, steam can
be very efficiently utilised either for single-stage expansion or in
compound working, though, rather curiously, in locomotive engineer-
ing, the trials which have been conducted in various parts of the
world, notably Germany and Canada, have shown that there is
comparatively little advantage by combining compounding and
superheating, thus indicating that in large measure they constitute
equivalent methods of using the steam.
The fact that the volume of the steam is also increased is also the
cause of economy, as a greater quantity of steam at the required
pressure is therefore available at the cylinders than is actually
generated by the boiler, the necessary additional work units
represented thereby being obtained by the utilisation of heat from
the furnace gases before they finally pass away, and after they have
passed through the boiler fire tubes.
CHAPTER II.
THE COMPOUND USE OF STEAM FOE
LOCOMOTIVE ENGINES.
CONTENTS : General Remarks Comparison of Locomotive and other Steam
Engines as regards Compounding Reasons for and against Compounding for
Locomotives Adaptation of Locomotive Engines for greatly varying Con-
ditions of Work Direct and Indirect Economy due to Compounding
Mechanical Advantages obtained by Compounding Additional First Cost
and Complication The Influence of Compounding on the Fireman's Work.
General Remarks. The question of the advantages, or otherwise, of
compounding for locomotives has provided subject-matter in past
years for some of the most heated controversies ever conducted in
the technical press, and even to-day, after nearly thirty years of
practical use of compound locomotives, the engineering world is not
yet altogether decided as to whether compounding for locomotives is
really satisfactory for all-round miscellaneous work. Compound
locomotives are to-day in use to the number of many thousands, and
about thirty systems of compounding have been introduced, on a
more or less large scale ; but for one locomotive engineer who favours
compounding, at least two can be cited who do not consider com-
pounding really satisfactory, or who, in their practice, continue to
design non-compound engines. Moreover, if one deletes from a list of
engineers in favour of compounding the names of those who are actually
connected with a particular system, the balance of opinion, as evidenced
by practice, becomes still more pronounced against compounding.
As an example showing the great diversity of opinion which exists
among responsible locomotive engineers, it may be mentioned that
the writer recently received letters from, among others, the Chief
Locomotive Engineers of three important American railways, wherein
statements were made which substantially amounted to (1) "I have
no compound locomotives, and do not desire any"; (2) "I have a
large number of compound locomotives, but found them unsatis-
factory until important alterations and modifications had been
made " ; and (3) " I have a large number of compound locomotives,
and as I find them eminently satisfactory, I do not intend to revert
to the employment of non-compound engines."
In Great Britain the compound locomotive appears to be in
5
6 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
particular disfavour, for, except for a few desultory experiments,
only two railways, the London and North- Western and the North-
Eastern, have ever introduced compound locomotives in large
numbers ; and on both of these lines many such engines have been
scrapped or converted to non -compound, and superseded by simple
engines, while on other lines, until the past two or three years, the
few compound engines have all been converted to non-compound,
with the exception of the Belfast and Northern Counties and the
Belfast and County Down Railways in Ireland. Recently, however,
engines have been built which indicate a revival of interest in
locomotive compounding, and a number of modern compound engines
are to-day in use on the North-Eastern (one three-cylinder engine
and two new four-cylinder engines), Midland (about forty three-
cylinder engines), Great "Western (three four-cylinder de Glehn
compound engines, purchased in France), Great Central (two three-
cylinder engines, just introduced), Lancashire and Yorkshire (two
experimental four-cylinder engines), and Great Northern (two engines
of different four- cylinder systems) Railways. On the Belfast and
Northern Counties Railway (now amalgamated with the English
Midland Railway) a few two-cylinder engines have been built since
the commencement of the twentieth century, and these are the only
recently built two-cylinder compound engines in Great Britain.
Some of the Webb compounds on the London and North-Western
Railway are of recent date, but otherwise the above list of new
engines represents the total number of modern compound locomotives
used in Great Britain at the time of writing (October 1906).
This can hardly be considered as a strong argument in favour of
compounding for locomotives, though recent work provides, to some
extent, an indication that British engineers are more dissatisfied
with compound systems than with compound locomotives. On the
other hand, it must be remembered that many British engineers
prefer to work on non-compound lines, and to design engines which
can do all and any work required of them, than to introduce new
features or special classes of engines merely because of economy,
coupled, perhaps, with a want of elasticity for varied service.
Abroad, however, the compound locomotive is in many cases
regarded with great favour, though in numerous instances the
situation is very similar to that existing in this country. In France
and Austria all the important railways now employ compound
locomotives almost exclusively, while in Germany, Italy, Hungary,
Russia, Norway, Sweden, Switzerland, and America (North and
South) there are large numbers of compound locomotives in use ;
but in Belgium (the year 1905 has witnessed the introduction of a
number of compound trial engines), Holland, Denmark, Spain and
Portugal, Canada, Australia, India and New Zealand, compound
engines are used in small numbers, or they exist only according to
old designs, being superseded by modern non-compound engines, or
all engines are non-compound.
It will thus be seen that, to account for this diversity of opinion
THE COMPOUND USE OF STEAM FOR LOCOMOTIVE ENGINES. 7
and practice among locomotive engineers, it must be allowed that
compounding for locomotives is not nearly so advantageous as
compounding for other steam engines, or else there must be special
reasons why compound locomotives should be so largely regarded
with disfavour, though where they are used extensively one hears
nothing but praises of their performances and economy ; and, as a
first step towards the elucidation of the complicated problem thus
presented, it will be most satisfactory if the main conditions of
marine and stationary steam engineering, and of locomotive
engineering, as regards compounding, are stated side by side, for
purposes of comparison.
Comparison of Locomotive and other Steam Engines as
regards Compounding :
For Marine and Stationary
Steam Engines :
(1) The range of pressure
rendered available for useful
work by compounding extends
from boiler pressure down to
atmospheric pressure, or to about
10 or 12 Ibs. per square inch
below when a condenser is
employed. Thus, if the initial
pressure is 180 Ibs. per square
inch, and by ordinary one-stage
expansion this can be reduced to
60 Ibs. per square inch, the final
pressure may (by compounding)
be as low as 5 Ibs. per square
inch, or as low as - 10 Ibs. per
square inch, a gain of 55 or 70
Ibs. of steam pressure.
For Locomotive Steam Engines :
(1) The range of pressure
rendered available for useful
work by compounding extends
from boiler pressure down to (at
least) 20 Ibs. per square inch, if
not a higher pressure, as no
condenser can be employed, and
a sufficient final pressure must
be maintained for blast purposes.
Tims, if the initial pressure is
180 Ibs. per square inch, and by
ordinary one-stage expansion this
can be reduced to 60 Ibs. per
square inch, the final pressure may
(by compounding) be about 20 or
25 Ibs. per square inch, so that
the possible gain is an additional
40 or 35 Ibs. of steam pressure.
It will therefore be seen that
the possible advantages due to
compounding may not be much
more than half that possible
with other types of engines,
particularly those working with
a condenser. When high initial
pressures are used, however,
unless very early cut-off is used,
which may be unsatisfactory, it is
only compounding that will en-
able sufficiently extended expan-
sion to be carried out, to avoid the
exhaust steam being discharged
at a wastefully high pressure.
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
(2) The speed of running is
almost invariable.
(3) The amount of work being
done is nearly constant.
(4) The engine is designed
and specially adapted for given
conditions.
(5) The engine runs for long
periods under specified and
almost invariable conditions.
(6) The engine is usually
controlled by a governor, or is
controlled in such a way that
the individual methods of the
engineer in charge are not mat-
ters of great importance.
(7) The engine works under
favourable circumstances, and it
can be designed, as regards
dimensions, without very severe
restrictions.
(8) Valve gear is adjusted for
the best and most satisfactory
steam distribution, and when
adjusted, is rarely varied. If
desirable, complicated and special
(2) The speed of running is
continually varying.
(3) The amount of work being
done is continually varying, with-
in wide extremes.
(4) The engine is designed so
as to be suitable and satisfactory
for extreme variations of working
conditions.
(5) The engine rarely runs for
many minutes without the condi-
tions and requirements varying,
owing to change of grade,
increase or decrease of speed,
curves, weather conditions, etc.
Moreover, a particular engine has
to meet requirements which vary
with every train it works, and
from day to day, even when the
same train is worked over the
same road.
(6) The engine is controlled
arid adjusted, as conditions and
requirements vary, by a driver
who cannot be expected to work
the engine in the best and most
economical way at all times.
Moreover, the methods of a
particular driver are important
matters, one driver working an
engine so as to give very good
results, while another driver will
work the same or a similar
engine with only average or
with unsatisfactory results.
(7) The engine often works un-
der unfavourable circumstances,
and its design is usually con-
trolled by dimensional limitations
and other considerations. The
engine is, moreover, subjected to
severe strains, owing to the fact
that it forms part of a travelling
power station.
(8) A simple form of valve
gear must be employed, and it
must be capable of an extensive
range of adjustment, in all cases
giving a fairly good steam distri-
THE COMPOUND USE OF STEAM FOR LOCOMOTIVE ENGINES. 9
valve gears can be conveniently
employed.
(9) Various refinements of
design can be employed, such as
expansion gear, governors, etc.
(10) The boiler has to provide
a regular supply of steam with
little variation ; and once the rate
of steam generation required to
supply the engine is settled, it
works with regular strain and
under favourable conditions.
bution, while the engine rarely
works for long under conditions
for which the valve gear will
give a really economical steam
distribution.
(9) Simplicity and general
reliability are far more important
features than refinements of
design, and special devices can
rarely be employed.
(10) The boiler has to be a
rapid steam generator, and able
to supply sufficient steam to
meet greatly varying require-
ments, and sometimes to meet
special strain. It therefore
follows that it cannot always
be operated in an economical
manner.
When the above comparisons are carefully considered, it will be
seen that the operation of steam in the locomotive engine is
necessarily controlled in so variable a manner, and the conditions of
work vary so greatly, that it is not surprising that in many cases the
greater proportion of any gain which should result from compounding
is neutralised by other considerations, and that at times the non-
compound engine may be more suitable for the required conditions
than the compound engine.
It must, however, be understood that in thus presenting the case
for the compound locomotive, the writer does not wish to infer that
compounding is not satisfactory for locomotives, for experience has
shown that compounding can be and is satisfactory and advantageous,
but rather to explain why it is that the gain is not so great as
it should theoretically be, and why the compound locomotive in
many instances has shown little apparent advantage for very varied
duty.
So far, compounding for locomotives has been considered merely
as a principle, but it is applied in many different ways, and it is
sometimes employed in such a way that mechanical and other
advantages are incidentally obtained ; and as a second step in
argument, the principal reasons for and against compounding for
locomotives will now be considered.
Reasons for and against Compounding for Locomotives. When
two cylinders only are employed, one high-pressure and the other
low-pressure, the engine depends for its efficiency as a compound
principally on its economy, though there are also advantages due to
the uniformity of pull and thrust transmitted through the piston-
rods, and in many systems provision is made for working non-
compound to provide additional power on occasions. The latter
10 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
considerations are not, however, of very great importance in the
case of two-cylinder engines, apart from economy.
Adaptation of Locomotive Engines for varying Conditions of
Work. For starting, a two-cylinder engine must have means for
working the low-pressure cylinder with boiler steam, for otherwise,
should it stop when the high-pressure crank is on a dead centre, or
the slide valve be closing both steam ports, the engine would be
unable to start if such means were not provided ; and in many cases
this provision is utilised to enable the engine to work non-compound
for some time after starting, or, on other occasions, to overcome
temporary difficulties. The presence of devices for this purpose
starting and intercepting valves constitute the usual arrangements^
either automatic or under the driver's control introduces complica-
tion and adds to the number of fittings which can get out of order,
while, if not intelligently controlled by the driver (if under his
control), the engine may operate unsatisfactorily, and when not
under his control, the driver may be more or less seriously handicapped
in operating the engine to suit all sorts of work. In fact, what is
termed a want of " elasticity " is one of the principal reasons which
have caused the rejection of two-cylinder compound locomotives in
many cases.
A compound engine with two cylinders only generally requires to
be kept fairly closely to the work for which it is designed. It may
be able to exert very great power at times, and in many instances,
when a long steady pull with a heavy train over several miles of
rising gradient is necessary, a compound engine can keep a train
moving, owing to the uniformity of its effort, when a non-compound
engine would be " stalled " ; but against this must be set the fact
that if non -compound working is maintained for long, the steam may
become choked or be used in a very extravagant manner, so that the
advantage of compounding at other times is more than counter-
balanced.
Furthermore, if a late cut-oif is employed for the high-pressure
cylinder, it is generally necessary to cut off fairly late in the low-
pressure cylinder also ; and when the engine works for a considerable
time the division of work between the two cylinders may be very
unequal, so that the engine works not only uneconomically but
unsatisfactorily, whereas a non-compound engine may work at its
best under these conditions as regards power, although it is, of course,
temporarily extravagant.
Therefore, if a two-cylinder compound engine for express passenger
service can be always employed on fast work, or a goods engine
be always used with heavy trains for long distances, both work-
ing over fairly level lines with long hauls, it may be taken as a
foregone conclusion that it will prove satisfactory and economical as
compared with a non-compound engine ; but when the duty is varied,
one trip express, the next with frequent stops ; one day with heavy
long-distance trains, the next with a light short-distance train ; one
turn requiring the engine to work over severe gradients, another
THE COMPOUND USE OF STEAM FOR LOCOMOTIVE ENGINES. 11
entailing a long easy journey ; then it is hardly to be wondered at
that the advantage obtained in some cases is neutralised by weakness
or extravagance in other cases. For tank engines with frequent stops
and short runs, and with very miscellaneous duties, two-cylinder
compound engines are rarely quite satisfactory, though many of them
are in existence and do good work.
In countries where fuel is very expensive, it may be that two-
cylinder compound engines provide sufficient economy to justify their
extensive use, but where the advantage in this direction is less, as it
is in this country, the comparative disadvantages due to causes above
specified may justify a preference for non-compound engines.
Moreover, British non-compound locomotives are well known to be
economical in coal consumption, so that the compound locomotive
has less opportunity to show its superiority than in some other
countries.
It must also be remembered that where work is greatly varied, the
personal equation of the driver is a most important factor; and one
British locomotive superintendent once stated that he could obtain
greater economies by selecting his drivers than were claimed for
compounding, while another engineer, himself the introducer of one
of the most widely-used systems of two-cylinder compounding, stated
that a principal reason for his adoption of compounding was the
endeavour to force the drivers to work their engines economically,
whereas they often worked somewhat extravagantly when they
possessed the free hand given by simple working.
Mechanical Advantages obtained by Compounding. When more
than two cylinders are employed, compounding introduces other
possibilities besides that of direct economy, and there is little
question that it is because of these that compounding is now
regarded with greater general favour than formerly, though many
three- and four-cylinder compound locomotives have been in use
for a number of years.
In all multi-cylinder compound engines there is a balance of parts,
the cylinders being similarly arranged on either side of the longi-
tudinal centre-line, and therefore, no matter how the work is divided
between high- and low-pressure cylinders, it is distributed nearly
equally for the longitudinal halves of the engine, whereas a two-
cylinder engine has two cylinders of different sizes, and the steam
distribution cannot always be arranged so that the forces upon the
two cranks are equal, or nearly so.
It therefore follows that in a three- or four-cylinder engine it is not
absolutely necessary that the work of the respective cylinders be
equally divided, though it is advisable that this be so, and under
average working conditions it is necessary for efficiency.
With tandem and other two-crank systems the chief advantages
are the same as those obtained by two-cylinder compounding, together
with a few other advantages due to the multiplicity of cylinders;
but with three- and four-crank systems various mechanical and other
advantages may also be obtained, which advantages are in some cases
12 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
of greater importance than direct economy of fuel and steam con-
sumption.
One of these advantages is that the cranks can be so arranged that
they follow one another with a more frequent crank sequence than
is the case with two cranks at right angles, as in two-cylinder or two-
crank engines, thus dividing the work up more equally, and giving a
more regular turning-moment, while balancing is assisted. These
matters are dealt with more fully in the next chapter.
Another advantage is that the work can be distributed over separate
axles when three or four cylinders are employed, and parts can be
made lighter and the strains due to the momentum of moving bodies
reduced, while the division of work sometimes enables wheel arrange-
ments to be used which are not possible satisfactorily when all the
work is transmitted through one axle which is coupled with all other
driving wheels.
Direct and Indirect Economy due to Compounding. But a princi-
pal advantage attending the use of three or four cylinders consists in
the fact that while direct economy may be obtained by the compound
use of steam under favourable circumstances, indirect economy may
be obtained at other times, owing to the fact that it is possible to
arrange for greatly augmented power by working non-compound
temporarily, whereby the engine is enabled to deal with trains which
would otherwise require an assisting engine, possibly only necessary
for a small section of a total journey, though such assisting engine
may, for traffic reasons, have to go the whole or a large portion of a
trip ; or to do work for which another engine would be severely
handicapped. The provision of such facilities may also render very
fast bookings with heavy trains practicable, owing to the fact that
the engine is able to exert abnormal power at times, as for obtaining
rapid acceleration, so that temporary extravagant working is really
synonymous with valuable indirect economy.
It will be gathered from the foregoing that the writer is more in
favour of compounding with three or four cylinders operating three
or four cranks than with two-cylinder or two-crank systems, and
this seems to be borne out by recent practice and the performances
of recent locomotives in all parts of the world ; but it has to be
acknowledged that, when conditions are favourable, two-cylinder
compound engines can and do work very satisfactorily, and four-
cylinder two-crank engines must be ranked between the two-cylinder
and the four-cylinder four-crank engines for efficiency.
The advantages thus briefly reviewed are not in all cases obtained
with every system of the class, as some systems possess features which
either render them specially satisfactory or militate against their
success in work ; but, as general statements, the above may be said
to be fairly accurately descriptive of the main divisions of practice.
The principal advantages which can or should be obtained by
compounding may be briefly stated as follows :
(1) Two-Cylinder Systems.
(a) Economy of fuel and steam consumption.
13
(b) Uniformity of pull and thrust.
(c) Temporary augmentation of power by using boiler
steam (generally proportionately reduced in pressure
for use) after starting, according to many systems.
(2) Three- or Four-Cylinder, Three- or Four-Crank Systems.
(a), (b), and (c) as above.
(d) Regular turning-moment due to use of three or four
cranks.
(e) Partial balancing.
(/) Large reserve of power by non-compound working, which
may be continued for comparatively long periods.
(g) Division of work over two driving axles (some systems
only).
(3) Four-cylinder Two-crank Systems.
(a), (b), and (c) as above.
(d) Incidental advantages due to multiplicity of cylinders.
Before concluding this chapter, reference must be made to first
cost arid complication, and to the matter of compounding in reference
to the work of the fireman.
Additional First Cost and Complication. At one time very great
objection was raised to compound locomotives, especially those having
three or four cylinders, on the score of increased first cost and
constructional complication ; but it has been shown by practice that
these matters are by no means so serious as they might appear to be.
With two cylinders these items are comparatively small, the only
features whereby such engines are differentiated from non-com-
pound engines being (1) the use of a small and a large cylinder,
and (2) the provision of starting and intercepting valves or equivalent
devices, and mechanism for controlling them (if not automatic),
complication relating only to such valves and mechanism.
With four-cylinder two-crank systems there are necessarily
additional cylinders, pistons, valves, etc., but additional valve gears
and motion are not required, and the starting arrangements may be
of a simple character.
With four-cylinder four-crank engines and with three cylinders,
each cylinder requires a complete set of motion, though two valve
gears can be made to control the steam distribution of four cylinders,
and the additional first cost may be considerable, though starting
arrangements are usually simple ; but experience has shown that this
is more than repaid by increased efficiency, and the fact that there
are additional parts liable to failure and increased complication is
not so serious as it might appear to be. Indeed, some engineers
argue that to attempt to economise by using two valve gears only
or by arranging all cranks on one axle is not the best policy, and
that the increased complication, if it tends to efficiency, is most
advantageous in the long-run.
The Influence of Compounding on the Fireman's Work. In the
case of a simple engine the blast is usually somewhat violent, and
waste of fuel sometimes results because incompletely consumed coal
14 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
is drawn through the boiler tubes and ejected before it has been
properly burnt. This occurs particularly when the engine is
working hard, and just at the time when the strain upon the boiler
is most severe, owing to the necessity for a large supply of rapidly
generated steam ; and at other times the intense blast may tend to
"drag the fire to pieces," as it is termed.
With a compound engine, however, the blast is usually a soft
one, owing to the large volume and low pressure of the escaping
steam, and in some engines there are only two exhausts per revolution
instead of four as usual. Consequently the fuel is not so often, if
at all, ejected from the chimney or drawn through the tubes half
consumed, although no difficulty should be experienced in main-
taining steam when the fireman has learnt how to fire under
these circumstances, and thus economy results quite apart from
the compound use of steam.
CHAPTER III.
A CLASSIFICATION OF COMPOUND SYSTEMS.
CONTENTS : Principal Features of Classification Cylinder Arrangements for (1)
Two-cylinder Systems ; (2) Three-cylinder Systems ; (3) Four-cylinder Four-
crank Systems ; (4) Four-cylinder Two-crank Systems ; (5) Tandem Systems ;
(6) Articulated Engines Cylinder Ratios Receivers and Receiver Capacities
Arrangement of Cranks, Division of Power, Balancing Valves, Valve Gears,
Independent Adjustability of Valve Gears for High- and Low-Pressure
Cylinders, Character of Steam Distribution Starting and Intercepting Valves.
Principal Features of Classification. The various systems which
have been, or are now, employed for compound locomotives may be
classified in several ways, and the following sets forth the principal
features upon which any classification must be based :
(1) The number of cylinders employed.
(2) The location and character of the cylinders.
(3) The ratio between high- and low-pressure cylinder volumes.
(4) The number of axles directly driven from these cylinders.
(5) The arrangement, or not, of the cylinders, motion, and cranks
to facilitate balancing.
(6) The provision, or not, of a receiver, and the ratio of receiver
to cylinder volume.
(7) The relative angles at which the cranks are placed (for three-
or four-cylinder systems only).
(8) The employment of one slide or equivalent valve to control
the steam distribution of each cylinder, or of each pair of cylinders,
one high- and one low-pressure.
(9) The employment of two, three, or four sets of valve gear for
two or four, three or four cylinders respectively, and the provision, or
not, of means whereby the high- and low-pressure valve gears can be
independently adjusted, or whereby the high-pressure valve gear
can be adjusted while the low-pressure valve gear maintains a
constant cut-off ratio.
(10) The nature and design of starting and intercepting valves.
(a) Automatic, the engine starting with boiler steam (generally
at a reduced pressure) in the low-pressure cylinder or cylinders, and
the valve or valves closing automatically as soon as the high-pressure
exhaust attains sufficient pressure for working in the low-pressure
15
16 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
cylinder or cylinders. The change from non-compound to compound
working usually takes place after three or four strokes only, so that
engines having valves of this class cannot be worked non-compound
even temporarily. In fact, the principal reason for fitting starting
and intercepting valves is to enable the engine to start with the
low-pressure cylinder (in the case of a two-cylinder engine) when
the high-pressure crank is on a dead centre.
(b) Under driver's control, so that the engine can be worked with
boiler steam in the low-pressure cylinder or cylinders for as long as
required at starting, or temporarily at other times.
(c) Combined automatic and under driver's control, automatic
working resulting immediately after starting, unless the driver has man-
ipulated a device whereby he can continue non-compound working.
(d) In several systems no starting valve, and sometimes no inter-
cepting valve, is fitted, starting being provided for otherwise, or the
engine being confined to compound working.
Starting valves and intercepting valves can also be classified, as
will be seen in subsequent chapters, according to their types flap,
piston, double piston, slide or lift valve and according to whether
they are separate valves, or whether one valve serves both purposes.
They can also be classified according to whether the intercepting
valve is automatic in operation, the starting valve being non-
automatic, or whether both are automatic or both non-automatic.
Strictly speaking, the construction, arrangement, and operation of
the starting and intercepting valves, or other starting devices or
means for working non-compound, constitute the principal features
whereby the various systems are differentiated, for other features
are more or less dependent thereupon.
In practice, however, it is not convenient to classify the systems
so elaborately as in the foregoing list of divisions, and therefore a
simpler classification will be followed in this chapter, as under:
(A) The number, location, character, and relative proportions
of cylinders.
(B) The use or non-use of a receiver, and the ratio of receiver to
cylinder capacity.
(C) Crank angles, number of cranks, division of power over two
axles, balancing, etc.
(D) Slide valves, number of sets of valve gear, relative adjusta-
bility of high- and low-pressure valve gears, character of
steam distribution, etc.
(E) Starting and intercepting valves or equivalent devices.
A. I. Two-cylinder Systems. Most of the earlier compound
locomotives had two cylinders only, a primary object of their de-
signers being to adapt engines of existing types and designs for
compounding with as little alteration and as much simplicity as
possible, while in many instances old engines were adapted as com-
pounds for experimental purposes. Provision had also to be made
in some cases for the easy conversion of compound engines to non-
A CLASSIFICATION OF COMPOUND SYSTEMS.
17
FIG. 1. Arrangement of Inside Cylinders
Two -cylinder Systems.
compound engines in the event of their proving unsatisfactory.
During succeeding years two-cylinder compound locomotives were
introduced in all parts of the world ; and although three- and four-
cylinder engines have been built in large numbers for many years,
it is probable that the two-
cylinder engines still out-
number all other compound
locomotives.
In all two-cylinder com-
pound locomotives the high-
pressure cylinder has a dia-
meter about equal to that
of a corresponding non-com-
pound engine, and the low-pressure cylinder has a considerably
larger diameter, the proportions being such that the work done in
each cylinder shall be about equal under average conditions.
In consequence of their similarity to ordinary engines, two-
cylinder compound locomotives rarely differ to any appreciable
extent, except in respect of the
starting arrangements and the
fact that one cylinder is larger
than the other; and there-
fore, for present purposes, no
more need be said than to
refer to figs. 1 and 2, which re-
present diagrammatically the
FIG. 2. Arrangement of Outside Cylinders cylinder arrangement for an
Two-cylinder Systems. inside-cylinder and an outside-
cylinder engine respectively.
II. Three -cylinder Systems One High-pressure and Two Low-
pressure Cylinders. Two systems are, or have been, in use, having
the three cylinders thus distributed, though similar systems have
been proposed, some of them in the very early days of compounding
for locomotives. Both of these systems are, or have been, applied
according to two methods (1)
the three cylinders all actuat-
ing the same axle (fig. 3), or
(2) the high-pressure cylinder
driving one axle and the two
low-pressure cylinders driving
another axle (fig. 4).
The system identified with
the Swiss Locomotive Works
of Winterthur has been applied
somewhat extensively in past years, almost exclusively, however,
for engines for Swiss railways, but is now largely superseded by
four-cylinder systems.
The Smith system, of British origin and use, is, on the other hand,
essentially a recent one, and it appears probable that its use will be
FIG. 3. Arrangement of Cylinders Three-
cylinder Systems (one H.P. and two L.P.).
18
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
largely extended in the near future. At present, all of these engines
(with the exception of two) have the three cylinders driving the
same axle, but the system can be equally well applied so that the
work is distributed over two axles. The system appears to indicate
that the compound locomotive may have an important future quite
irrespective of direct economy, for in actual use its chief advantage
seems to lie in the fact that it provides for a great and yet variable
FIG. 4. Arrangement of Cylinders Three-cylinder Systems
(oneH.P. and two L. P.).
reserve of power, which can be drawn upon to surmount gradients
or to deal with very heavy loads.
III. Three-cylinder Systems Two High-pressure and One Low-
pressure Cylinders. These systems, two in number, are both of
British origin, and each of them admits of the driving of one axle
only, or of two, by the cylinders.
The Webb system, used so largely on the London and North-
Western Railway at one time, is now superseded, and the seventeen
similar engines supplied to France, South America, India, and the
United States many years ago, were never multiplied ; but this some-
what paradoxical system constitutes one of the most important links
in the development of the compound locomotive.
In the case of the passenger and tank engines (fig. 5), the system
FIG. 5. Arrangement of Cylinders Webb Three-cylinder System.
was applied so that coupling rods could be dispensed with, the two
H.P. cylinders driving one pair of wheels and the single L.P.
cylinder driving another axle ; but in the case of a numerous series
of eight-coupled mineral engines the three cylinders actuated one axle
(fig. 6), and the wheels were necessarily coupled.
The Riekie system, also indicated by fig. 6, has been experimentally
fitted to converted engines in India, but has not been applied other-
""<"" It is, however, possible that it will be applied in British
wise.
A CLASSIFICATION OF COMPOUND SYSTEMS.
19
practice at an early date. Its principal characteristics are (1) the
arrangement of the cranks at angles of 120 apart; (2) the non-
provision of any special starting means ; and (3) the fact that the
high-pressure cylinders are designed to operate in exactly the same
way as the two cylinders of a
non-compound engine, cutting
off early in the stroke, the
function of the low-pressure
cylinder being to enable fur-
ther work to be extracted from
the steam before it is exhausted
up the chimney This system ^ 6 ._ A ent of Cylinders _ Three-
has been applied with the cylinder Systems (two H.P. and one L.P.).
cylinders all driving one axle,
but it can be applied with the H.P. cylinders driving one pair of
coupled wheels, and the L.P. cylinder driving another pair of wheels.
IV. Four-cylinder Balanced Systems. Engines having four
cylinders actuating separate cranks on one axle are generally
termed "balanced" compound engines, as there is always one
piston working in exactly oppo-
site phase to another, so that
balancing by counterweights on
the driving wheels is largely
reduced. Several sj'stems of
this class are in extensive use.
As a rule, the high-pressure
cylinders are placed outside the
frames (fig. 7), but in some
cases the low-pressure cylinders
According to most systems, the pistons
FITT:
FIG. 7. Arrangement of Cyli
Four-cylinder Balanced Sys
linders
ystems.
occupy that position (fig. 8).
of adjacent high- and low-pressure cylinders always move oppositely,
so that steam can pass directly from one to the other, the cranks of
the two cylinders on one side of the centre line being arranged 180
apart, while the cranks of the other two cylinders are at right angles
to the first-mentioned cranks,
but at angles of 180 to each
other. In fig. 7 the cranks at
each side are at angles of 90,
and in fig. 8 they are arranged
as mentioned.
V. Four - cylinder Divided
and Balanced Systems. Sys-
tems of this class provide for
two pairs of coupled driving
wheels, one pair being operated
FIG. 8. Arrangement of Cylinders
Four-cylinder Balanced Systems.
by the high pressure cylinders and the other pair by the low-
pressure cylinders. As the wheels are coupled, these systems pro-
vide for balancing, but the work is divided over two axles ; hence
the usual descriptive term "divided and balanced."
20
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
In fig. 9 the outside high-pressure c} T linders are set back on the
frames and drive the rear pair of wheels. Occasionally the positions
of the respective cylinders are reversed. In fig. 10 the four cylinders
are placed in line, the outside cylinders having long connecting rods.
FIG. 9. Arrangement of Cylinders Four-cylinder Divided and
Balanced Systems.
Fig. 11 corresponds to fig. 10, but low-pressure cylinders are placed
outside the frame. The arrangement shown by fig. 12 has only
been used for a few engines, but it is worthy of note. In this case
the high-pressure cylinders are set back between the frames, and are
FIG. 10. Arrangement of Cylinders Four-cylinder Divided and
Balanced Systems.
placed at an angle so that their rods can pass over the front coupled
axle to drive cranks on the second coupled axle.
Most of the compound systems which are being applied for recent
engines on a large scale, such as the de Glehn, von Borries, Gdlsdorf,
and Vauclain, together with other recent systems, such as the Webb,
FIG. 11. Arrangement of Cylinders Four-cylinder Divided and
Balanced Systems.
Cole, Ivatt, etc. systems, belong to one or other of these two four-
cylinder classes, as will be seen hereafter.
VI. Four-cylinder Two-crank Tandem Systems. Experimentally,
the use of four cylinders arranged tandem fashion dates back right
to the early days of compounding for locomotives, for it has the
A CLASSIFICATION OF COMPOUND SYSTEMS.
21
advantage that only two sets of motion are employed, and ordinary
locomotives can be fairly easily adapted by using the original
cylinders for low-pressure, and fitting smaller high-pressure cylinders
in front, the pistons of each pair being upon the same rod. About
1886 and 1887 there were several experiments carried out in Great
Britain with such engines, and for some dozen years or so they have
been built occasionally in the United States, a few of the engines
being recent and notable machines. Their principal employment
FIG. 12. Arrangement of Cylinders Four-cylinder Divided and
Balanced Systems.
has been, however, in Hungary and Russia, and in the history of
French locomotive development they are to be found as far back as
1882 and as recently as 1905, all of the engines being still in
service.
Tandem compound locomotives can be divided into two main
divisions: (1) where each pair of cylinders (one H.P. and one L.P.)
are closely connected, one slide valve controlling the steam distribu-
tion ; and (2) where the cylinders are separated, each having its own
FIG. 13. Arrangement of
Tandem Cylinders.
FIG. 14. Arrangement of
Tandem Cylinders.
FIG. 15. Arrangement of Tandem Cylinders with three Piston Rods.
slide valve, though necessarily the two slide valves of each side of
the engine are fitted on the same valve rod. These features are
dealt with specifically in Chapter IX.
In fig. 13 the high-pressure cylinder is placed in front of the
low-pressure cylinder ; in fig. 14 the arrangement is reversed. The
arrangement shown in fig. 15 has been employed in a few cases, the
low-pressure piston having two piston rods, which pass one on either
side of the high-pressure cylinder, so that there are three piston rods
connected to each crosshead.
22
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
VII. Four-cylinder Two-crank Systems (other than Tandem). In
this division two systems are included, so far as actual practice is
concerned.
According to the Vauclain system (used very largely in America),
there is a high- and a low-pressure cylinder superposed at each side,
the piston rods of each pair being connected to the same crosshead,
FIG. 16. Arrangement of Superposed
Cylinders Vauclain System.
FIG. 17. Arrangement of Superposed
Cylinders Vauclain System.
so that the engine corresponds in other respects to an ordinary two-
cylinder non-compound engine. The steam distribution of each pair
of cylinders is controlled by one special piston valve. In fig. 16
the high-pressure cylinder is uppermost, and in fig. 17 the low-
pressure cylinder occupies that position. The former arrangement
is generally employed for passenger engines and the latter for goods
engines.
The Johnstone system has
been employed for about a
dozen engines in the United
States. According to it, each
high-pressure cylinder is sur-
FIG. 18. Arrangement of Cylinders
Johnstone Annular System.
rounded
by an annular low-
pressure cylinder which has
two piston rods, the three piston rods being connected to one
crosshead (fig. 18).
VIII. Four-cylinder Articulated Systems. Locomotives compounded
in this fashion have the coupled wheels arranged in two distinct sets,
two cylinders driving one set of coupled wheels and two cylinders
driving the other set of coupled wheels. In most cases the Mallet
FIG. 19. Arrangement of "Wheels and Cylinders Articulated
Compound System.
system is employed, according to which the rear coupled wheels are
operated by the high-pressure cylinders and the front coupled wheels
are mounted in a pivoted frame and operated by the low-pressure
cylinders (fig. 19). The Meyer-Lindner system sometimes includes
this cylinder arrangement, but, as a rule, the cylinders are located
between the two sets of coupled wheels, one pair driving towards the
front of the engine and the other pair towards the rear. In some
A CLASSIFICATION OF COMPOUND SYSTEMS. 23
instances both sets of coupled wheels and cylinders are mounted on
pivoted bogie trucks.
It is believed that compounding has also been applied for double
bogie Fairlie engines, with one high-pressure and one low-pressure
cylinder operating each set of coupled wheels.
A few other cylinder arrangements have been proposed, and in one
or two instances actually applied, but these can only be referred to
in subsequent chapters incidentally.
Cylinder Ratios. Strictly speaking, the relative diameters of the
high- and low-pressure cylinders should be such that, under average
conditions, the amount of work done in the respective cylinders is
approximately equal; otherwise the division of the work will be
unequal, and injurious strains will be set up. This is particularly
important in the case of two-cylinder compound locomotives, for if
the work done in one cylinder exceeds that done in the other cylinder,
there will be a tendency to twist the engine laterally. But although
this equal division of power is very desirable, it cannot be fully
obtained in practice, for circumstances and requirements vary to so
great au extent that attention has to be paid to average conditions
of work, and it is never possible to adapt an engine so that it shall
be equally satisfactory under all conditions. Thus, if the cylinders
are suitably proportioned for a 40 per cent, cut-off in the high-
pressure cylinder and an 80 per cent, cut-off in the low-pressure
cylinder, the Hnking up of the H.P. valve to a 30 per cent, cut-off
will at once throw the L.P. steam distribution out of proportion.
Means have been provided in connection with some two-cylinder
systems whereby the valve gears for the two cylinders can be inde-
pendently adjusted, and this facility is a common feature of many
four-cylinder s} r stems now in use, but the provision of such means
is only a partial solution of the difficulty, and, as a rule, a suitable
medium is selected to govern design.
It therefore follows that the cylinders must be proportioned to
give the most satisfactory all-round results in this respect, and the
question of cylinder ratios is one to be decided more by experience
than by calculation. It is therefore not surprising that the practice
of different engineers presents considerable variation, and it will be
most satisfactory if the cylinder ratios generally employed are
specified.
For two-cylinder compound locomotives the ratio is usually about
1 : 2 or 1 : 2'25, though it is occasionally 1 : 2'5 or 1 : 2'75, or
even 1 : 3.
For three-cylinder compound engines, if only one H.P. cylinder is
employed, the three cylinders have about the same diameter, or the
L.P. cylinders are slightly larger, so that the proportion is 1 : 2 or
1 : 2'25. For example, the Smith compound engines on the Midland
Railway have a 19-in. H.P. cylinder and two 21-in. L.P. cylinders.
For engines such as the Webb three-cylinder locomotives, the
diameters have been 15 in. or 16 in. and 30 in., giving the ratio of
1 : 2, or slightly less.
24 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
In the case of four-cylinder compound locomotives the cylinders
are designed, according to various systems, with a wide range of
ratios, from as low as 1 : 1*7 to as high as 1 : 3. When the low
ratio is employed there is generally some special reason therefor,
such as, in the case, for example, of Webb four -cylinder engines, the
need for having H.P. cylinders sufficiently large for starting a train
unaided. When three or four cylinders are employed, it is not,
however, so important to have the work evenly divided between
high- and low-pressure cylinders as it is in the case of two-cylinder
engines.
In a few cases the H.P. and L.P. cylinders do not have the same
stroke, but such instances must be regarded rather as curiosities
than as examples of practice. When this occurs, the ratios have
to be computed by cylinder-volume instead of by cylinder-diameter.
B. Receivers and Receiver Capacities. For practically all com-
pound locomotives in which steam cannot pass directly from a H.P.
to a L.P. cylinder it is necessary to employ a receiver, or an
equivalent therefor, into which the exhaust steam from a high-
pressure cylinder passes and remains for a short period until it can
be admitted to a low-pressure cylinder. The provision of a receiver
is a necessity for two-cylinder compound engines, but in most three-
or four-cylinder engines it can be dispensed with, though one is
employed according to many such systems.
In all systems wherein a high- and a low-pressure piston move
together, as in tandem, annular and superposed cylinder arrangements,
a receiver is not necessary, as steam can pass directly from one
cylinder to the other ; and in other four-cylinder systems it is often
arranged that corresponding high- and low-pressure pistons shall
always move oppositely, their cranks being 180 apart. When, how-
ever, the H.P. and L.P. cranks are 90 or 135 or an indefinite angle
apart, as in Webb three-cylinder and other non-coupled engines, a
receiver is necessary.
As a rule, the receiver is constituted by the piping by which a H.P.
cylinder is connected with its corresponding L.P. cylinder, and the
requisite volume is obtained by coiling this pipe round the interior
of the smokebox. This method also possesses the advantage that
the steam is slightly reheated before it enters the low-pressure cylinder
or cylinders.
The receiver also acts in large measure as a reservoir, whereby any
inequalities of the pressure of steam entering from the H.P. cylinder
or cylinders is more or less compensated for in the receiver, which
acts to some extent as a storage chamber.
Receiver capacity is usually estimated in terms of the volume of
the H.P. cylinder or cylinders, but the practice of various designers
shows considerable variation. The most usual proportion is three or
four times the volume of the H.P. cylinder or cylinders, but it is
sometimes less, especially when more than two cylinders are em-
ployed, though two and a half times is about the minimum, and
some engineers recommend a capacity of five or six times.
A CLASSIFICATION OF COMPOUND SYSTEMS. 25
Receiver space is sometimes provided in the castings of the cylinders,
and in other cases large steam chests for the low-pressure cylinder or
cylinders and large or extended H.P. exhaust ports serve the same
purpose.
The study of the influence of the receiver in compound locomotives
is, however, a complicated one, and for extended consideration the
reader must be referred to Professor Wood's book already mentioned.
In most cases the receiver is fitted with a safety valve, which blows
off in the event of the steam pressure therein rising unduly. A
usual lifting pressure for such valves is about 80 Ibs. per square inch,
this being a very common admission pressure for use in the low-
pressure cylinder or cylinders.
C. Arrangement of Cranks, Division of Power, and Balancing.
For two-cylinder and two-crank compound engines the cranks are
always arranged at angles of 90, this corresponding with ordinary
non-compound practice ; but when there are more than two cranks,
various crank dispositions are used.
The usual arrangement for three-cylinder compound engines is to
place the two L.P. cranks (for Webb three-cylinder engines it is the
two H.P. cranks) at right angles, and the other crank bisects the
obtuse angle between them, being at 135 with respect to each of
the other cranks. Mr Riekie, in his system, however, advocates the
arrangement of the three cranks at angles of 120.
For four-cylinder four-crank systems the most common arrange-
ment is to dispose the cylinders in pairs, there being a high- and a
low-pressure cylinder on either side of the longitudinal centre-line
of the engine, the cranks of which are 180 apart, so that the re-
spective pistons are always moving oppositely, while the cranks of
one pair of cylinders are placed at right angles to those of the other
pair of cylinders. Consequently there are four cranks, driving at
angles of 90 around the circle of revolution, or, as it is sometimes
expressed, "four cranks quartering."
Occasionally this practice is departed from, such angles as 165
being employed between the cranks of each pair of cylinders, so that
the cranks are unevenly disposed. This is, however, unusual ; and
where it has been employed, this method has, so far as the writer is
aware, been discontinued.
In systems such as the Webb three-cylinder non-coupled and the
Mallet and Meyer-Lindner articulated systems, according to which
the high- and low-pressure cylinders drive separate non-connected
wheels or sets of wheels, the two sections of the engine can operate
for a few revolutions independently, but it is found that they quickly
adjust themselves, owing to the excess or shortage of steam from
the H.P. cylinder or cylinders, and when the engine is well under
weigh they work practically synchronously.
With three or four cylinders it becomes possible to divide the
work over two separate axles or two sets of coupled axles, and this
possibility is realised according to several systems, one or two
cylinders driving one axle and the other cylinder or cylinders
26 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
actuating the other axle. According to several systems, now dis-
continued, two pairs of uncoupled driving wheels are driven by
independent cylinders, H.P. or L.P. as the case may be; but in
present practice it is universal to coiiple them, so that the various
cylinders always operate in fixed relation, and if there is a tendency
for one pair of wheels to slip, or there is a loss of power for some
reason, that pair of wheels is assisted or kept in proper relation
by means of the coupling rods. When there are more coupled
wheels than the coupled driving wheels, they receive power from
both H.P. and L.P. cylinders.
When the power is thus divided between the cylinders, the parts
can often be made of lighter construction than when all the work is
transmitted through one axle.
An important advantage that results from three- or four-crank
compounding is the fact that balancing is greatly assisted because of
the multiplicity of cranks distributed fairly equally round the circle
of revolution, the moving parts of one set of motion being largely
counterbalanced by the moving parts of another set of motion.
With three cranks, arranged more or less evenly apart, the turning-
moment is very regular ; and the same occurs when there are four
cranks on one axle, or two each on coupled axles, arranged "quarter-
ing " or nearly so.
D. Slide Valves, number of Sets of Valve-Gear, relative Ad-
justability of High- and Low-pressure Valve Gears, character of
Steam-Distribution. With two cylinders only the question of valve
gears does not require extended consideration, for, as a rule, the
gears employed correspond generally to ordinary practice, except
that they will usually be adjusted to give proportionately corre-
sponding cut-off ratios in the two cylinders, instead of the same ratio
in each cylinder. According to a few systems, however, means are
provided whereby the two valve gears can be adjusted together or
independently, or the low-pressure valve gear maintains a fixed
expansion ratio.
With four cylinders, however, practice may be divided into two
main classes :
(a) Having separate valve gears for every cylinder ; and
(b) Having two valve gears, each governing the steam distribution
of two cylinders.
All three-cylinder compound engines have separate valve gears,
and, as a rule, they are each complete, though in a few cases some
of the Webb three-cylinder compound engines for example one of
the valve gears is of a simple type, and is dependent for its operation
on the working of other valve gears.
Four-cylinder compound locomotives are about equally divided
between the two classes.
When four cranks are employed, as in balanced, divided and
balanced, and articulated engines, it appears to be preferable to fit
each cylinder with its complete valve gear, although such practice
introduces complication and adds to first cost, as by so doing the
A CLASSIFICATION OF COMPOUND SYSTEMS. 27
valve gears can be independently adjusted, and in the hands of a
capable driver this facility allows of the steam distribution being
regulated proportionately in the high- and low-pressure cylinders,
according to varying conditions of work and requirements. In
some instances, however, especially those of recent date, although
both sets of valve gear can be operated together for reversal, it is
only the high-pressure gear that can be varied, the low-pressure
gear providing a fixed expansion ratio.
When two sets of valve gear only are employed, the cut-off ratios
are necessarily varied in fixed relation, as two valves, one for a high-
pressure cylinder and one for a low-pressure cylinder, have to be
operated from one set of valve motion. Usually, one valve is operated
directly in the usual way, and the other is operated either directly
or through a lever of the first order, whereby the valve is moved in
opposite phase from the first-mentioned valve. In a few instances
the motion comprises special elements, whereby provision is made for
adjusting the relative cut-off ratios of the two valves, although the
movements of both are derived from the same gear.
In some designs the steam distribution of a high- and a low-pressure
cylinder is controlled by one valve working over specially arranged
ports.
In the case of four-cylinder two-crank compound engines it is
usually possible to employ one valve for controlling the steam dis-
tribution of aH.P. and a L.P. cylinder, or to arrange two valves on
one valve spindle.
Instead of providing independently adjustable valve gears, it has
been also proposed to provide means whereby the admission steam
pressure for the low-pressure cylinder can be varied according to
working requirements by means of an adjustable safety valve fitted
upon the receiver, or by providing for a supply of boiler steam at
variable reduced pressure to the receiver for reinforcing the low-
pressure steam when necessary.
In most cases the cut-off ratios of high- and low-pressure cylinders
differ considerably, and as a rule the variations of cut-off permis-
sible are less than those possible in non-compound locomotives.
It may be stated as fairly descriptive of general practice that the
H.P. cut-off can be varied between 25 and 75 per cent, of the
stroke, while the L.P. cut-off can be varied only between 50 and 90
per cent, of the stroke. As mentioned, in many systems the L.P.
cut-off cannot be varied, and in such cases it will usually be fixed
at about 75 or sometimes 80 per cent, of the stroke.
E. Starting and Intercepting Valves. The last division neces-
sarily entails detailed technical description, and therefore it will not
receive consideration in this chapter, as most of the succeeding
chapters relate to its subject-matter in large measure. Sufficient
has already been said in the way of classification of starting and
intercepting arrangements for present purposes.
CHAPTER IV.
THE HISTORY AND DEVELOPMENT OF THE COMPOUND
LOCOMOTIVE.
CONTENTS: The earliest Suggestions The Nicholson-Samuel "Continuous-
Expansion" System The Sutcliffe and Salmon Proposals E. Kemp's
Tandem Single-acting System Joy's Four-cylinder Suggestion Morandiere's
suggested Three-cylinder Engine Weir's Three-cylinder System Fairlie
Double-bogie Type Dawes' suggested Four - cylinder Arrangements
Hudson's proposed Arrangement Mallet's first Engines Andrade's Three-
cylinder Design Holt's Designs for Compound Tramway Engines The
Struwe Three-cylinder Design Mallet's suggested Schemes Von Berries'
first Engines Worsdell's first Engines Webb's first Three-cylinder Engines
Sandiford's Experiments in India The Du Bousquet Tandem System in
France The Dunbar Tandem System The Nisbet and Great Western
Tandem Experiments Mallet's Articulated System Brief Review to Date.
The earliest Suggestions. The Nicholson-Samuel Continuous-
expansion System. Strictly speaking, the building in 1877 of
three two-cylinder compound tank engines according to Monsieur
Anatole Mallet's designs, for use on the Bayonne and Biarritz Railway,
a small line in the South of France, marked the commencement of
the history and development of the compound locomotive, for before
that date no compound locomotives for railway use had been actually
tried, though reference is made below to the Nicholson-Samuel
"continuous-expansion" system of 1850-2, and it is possible that
two or three compound tramway locomotives antedate the first
Mallet engines by two or three years (the writer has been unable
to confirm this) ; but particulars had been published concerning a
number of schemes for compounding locomotives, and many patents
granted in connection therewith, for at least twenty-five years
previously, some of which published schemes and patents require to
be briefly noticed, partly for completeness and because of their
interest, but principally in order that development may be correctly
traced.
It is sometimes stated that the first suggestion for applying
compounding to locomotives can be dated as far back as 1834, but
the writer has been unable to ascertain the correctness or otherwise
of this. According to a proposal published about 1845, a four-
cylinder system was proposed having two high-pressure and two
28
HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 29
low-pressure cylinders, one of each being arranged on either side of
the engine, one cylinder above the other, the connecting rods of
each pair driving on to the same crank pin.
In 1850 Mr J. Nicholson, an employee of the Eastern Counties
(now Great Eastern) Railway, devised a scheme which is closely
related to compounding, though it is generally described as a " con-
tinuous-expansion " system, and two engines were experimentally
adapted by Mr J. Samuel, the Locomotive Superintendent of that
railway, in 1852, one engine being a passenger and the other a goods
engine. This system had for its object to utilise the expansive
power of steam to an extent that was unknown at the period when
steam pressures were low and points of cut-off late in the stroke,
but it can hardly be called a compound system, though closely
allied thereto.
According to this system, steam was admitted to one cylinder for
half the stroke, and communication was then opened between the
two cylinders so that the steam could expand, not only for the
remaining half of the stroke in the first cylinder, but also for the
whole of the stroke in the second cylinder, the piston of which
would, of course, be just commencing its stroke at the time of
admission. It therefore followed that for half a stroke one piston
was subjected to full pressure, and for the remainder of the stroke
to a diminishing expansion pressure ; and in the second cylinder
steam at correspondingly diminishing pressure would act on the
piston for half of its stroke, after which the first cylinder would be
cut-off, and the steam then expanded still further for the remaining
half of the stroke. The two cylinders, which were of equal size,
operated alternately as first and second cylinders for the above-
described cycle of operations.
To enable the required steam distribution to be obtained, there
were two slide valves for each cylinder, four in all.
The general arrangement is shown by fig. 20, reproduced from a
diagrammatic drawing published by Monsieur Mallet many years
ago for comparison with his system. As will be seen, steam admission
has just been cut off in the left-hand cylinder, and communication
has just opened to allow steam to pass also into the right-hand
cylinder.
It was stated at the time that this curious method of working
proved very satisfactory, but after extended trial the engines were
converted back to their original condition. It is believed that an
engine was also adapted according to this system on the then
London and Brighton Railway.
The Sutcliffe and Salmon Proposals. In 1853 a Mr J. Sutcliffe
patented a curious three-cylinder compound system, according to
which two outside high-pressure cylinders operated the driving
axle directly, and a single inside low-pressure cylinder actuated
an axle which was geared by 2 to 1 gearing with the driving axle.
The low-pressure cylinder was supplied from both the high-pressure
cylinders, the low-pressure piston working at double the speed of the
30
LOCOMOTIVE COMPOUNDING AND SUPEBHEATING.
high-pressure piston, so as to use the exhaust steam from both of
them alternately. Owing to this peculiarity, the system fails to be
an anticipation of the well-known Webb three-cylinder system, for it
is really the equivalent of a four-cylinder system, the one low-pressure
cylinder serving the purpose of two.
In 1859 a four-cylinder system was patented by Mr P. Salmon, of
Glasgow, in which the two high-pressure cylinders were arranged at
the firebox end of the engine and adapted to drive the leading pair
of wheels, while the two low-pressure cylinders were located at the
smokebox end and drove the rear pair of driving wheels, so that the
respective connecting rods crossed one another, of course in separate
planes.
According to a modification, it was proposed that a high- and a
low-pressure cylinder should be placed one over the other at about
the centre of the engine, the pistons of the respective cylinders driving
FIG. 20. Arrangement of Cylinders and Valves Nicholson -Samuel
" Continuous expansion " System, 1850-2.
in the one case to the front of the engine, and in the other case to
the rear of the engine.
Other modifications suggest (1) the use of four cylinders placed in
line, the low-pressure cylinders being between the frames and all
connecting rods driving on to one axle ; (2) the fitting of the cylinders
in pairs outside the frames, the connecting rods at either side driving
on to the same crank pins ; (3) the use of one high-pressure cylinder
and two low-pressure cylinders, all acting on the same axle ; and (4)
what is practically the ordinary two-cylinder system, with inside
cylinders.
No details are given as to special starting arrangements, and it is
rather curious that the two-cylinder system is placed last, being
referred to almost as an afterthought, for the inventor evidently
believed three or four cylinders to be really necessary for compound-
ing, and this opinion seems to have been held by a number of the
early inventors who dealt with compounding for locomotives.
HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 31
E. Kemp's Tandem Single-acting System. A strange four-
cylinder system was proposed somewhere about 1860, and this may
have been actually tried, though very few particulars are available.
It represents a suggestion by Mr Ebenezer Kemp, and fig. 21 shows
the proposed cylinder arrangement. In this case the cylinders
were to be single-acting, the steam acting first upon the plunger
piston to force it in one direction, and then passing to the low-
FIG. 21. A Single-acting Four-cylinder Scheme, suggested about 1860.
pressure cylinder for acting upon the annular piston therein for the
return stroke.
Joy's Four-cylinder Suggestion. In 1866 provisional protection
was granted to the late Mr David Joy for a scheme according to
which the high-pressure cylinders were to actuate a pair of small
wheels and the low-pressure cylinders to drive a pair of larger wheels,
the different speeds of the two sets of driving wheels compensating
for the difference in working pressure of the steam in each case.
Morandiere's suggested Three-cylinder Engine. At the period
when the design of suitable locomotives for working traffic on the
FIG. 22. Three-cylinder System, suggested in 1866 by
Monsieur Jules Morandiere.
London Underground railways was attracting considerable attention,
Monsieur Jules Morandiere, of the Northern Railway of France,
proposed a three cylinder compound design, in which a single high-
pressure cylinder drove one set of four-coupled wheels and two low-
pressure cylinders drove another set of four-coupled wheels. The
general arrangement, as published in Engineering, is shown in fig. 22.
About 1870 several tandem arrangements were proposed in
England and in America, but none of them possess sufficient interest
for detailed reference.
32
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
Weir's Three-cylinder System. In 1871 a Mr J. Weir patented a
three-cylinder system, comprising the use of one high-pressure and
two low-pressure cylinders, all, however, operating upon the same
axle ; but though it is believed that the system has been actually
employed for stationary engines, there is no record of its use for
locomotives.
Fairlie's Double-bogie Type. In 1872 four patents were granted
in this country for compound locomotives, but only two of these are
worthy of notice. In Mr Fairlie's scheme an articulated locomotive
of the well-known Fairlie double-bogie type is fitted with tandem
compound single-acting cylinders.
Dawes' suggested Four-cylinder Arrangements. The other patent
mentioned (No. 1857, of 1872, granted to William Dawes) is by far
the most important of any before the actual commencement of the
practical era of the compound locomotive, for it discloses the general
features of most of the four-cylinder compound systems which have
been since employed, and also includes one or two which have never
gone beyond the suggestion stage.
FIG. 23. Four-cylinder Tandem System, suggested 1872.
Fig. 23 shows a tandem arrangement with the cylinders inside the
frames, the low-pressure cylinders being in front, two sets of valve
gear only being employed to control the steam distribution of the
four cylinders. A four-cylinder arrangement, wherein the high- pressure
cylinders are outside the frames and the low-pressure cylinders
between the frames, is shown in fig. 24. The four cranks are 90
apart, and two sets of valve gear only are provided. This arrange-
ment is characteristic of a good many of the systems now in use.
The arrangement shown in fig. 25 is somewhat notable, except
that the cylinders are of the oscillating type, because it sets forth
the division of work over two axles which are uncoupled, though this
feature also occurs in several proposals already referred to.
The specification does not describe any particular construction of
starting valve, but it is suggested that live steam can be admitted to
the low-pressure cylinders for starting or when required by valves
which can only be operated through the reversing gear when in the
extreme positions of full-forward or full-backward gear ; this feature is
comprised in several later systems which have been actually employed.
HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 33
Mr Hudson's proposed Arrangement. In 1873 Mr Hudson, then
Chief Engineer of the well-known Rogers Locomotive Works (U.S.A.),
patented a two-cylinder compound system for American locomotives.
A simple valve provides for admitting live steam to the low-pressure
cylinder at starting. This also was never carried into practice, and
it was many years before this firm commenced building two-cylinder
compound locomotives according to their now well-known system,
described later.
A British patent of this year suggests the fitting of a low-pressure
FIG. 24. Four-cylinder Four-crank System, suggested 1872.
engine upon the tender of a locomotive; and a patent of 1874
granted to an American engineer is notable for the fact that, besides
compounding, it also sets forth the use of superheated steam.
Mallet's first Engines. It was in 1874 that Monsieur Anatole
Mallet patented his two-cylinder system in France, though it was not
until 1876 that it was actually realised; and a few notes concerning
the early work of this gentleman, which entitles him to be described
as " the father of the compound locomotive," will be in place at this
FIG. 25. Four-cylinder System with Oscillating Cylinders, suggested 1872.
juncture, for the Mallet system is one of the two main systems from
which all the two-cylinder systems since introduced may be considered
to be derived.
The Mallet system is the original of the now extensive list of
systems according to which the driver is given complete control over
the use of boiler steam in the low-pressure cylinder, the Worsdell-
von Borries system (introduced 1880-1885) being correspondingly the
original of systems by which, after starting, an engine is automatically
converted to compound working.
Monsieur Mallet believed that the driver should be able to work
3
34
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
non-compound for as long as he deemed necessary at starting, and
not merely for a few strokes as in automatic systems ; and that, if
required, the driver should be able to work non-compound at other
times to overcome temporary difficulties.
The Bayonne and Biarritz Railway, a short line in the South of
France, opened in 1877, and depending largely on pleasure traffic for
its business, was the scene of work of the original Mallet compound
locomotives. For the opening of this railway three small six-wheeled
tank engines were designed by Monsieur Mallet, and built in 1876 by
Messrs Schneider & Co. of the well-known Creusot Works. In
designing these engines provision was made for their easy conversion,
FIG. 26. One of the first three Compound Locomotives Mallet System.
if necessary, to non-compound, but their record was so satisfactory
that the need never arose ; and although other engines were added
in succeeding years, this railway had the distinction of being the
only line in the world possessing none but compound locomotives,
which distinction was, it is believed, retained until the railway lost
its identity and became merged in one of the large railway systems
of France.
Fig. 26 illustrates one of the three original engines for this line,
and fig. 27 is a cross section thereof.
In 1878 several six-coupled engines were added, one of which was
exhibited at the Paris Exhibition of that year.
It may be mentioned that all these engines had very long chimneys,
owing to the fact that the carriages then in use were largely of the
HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 35
"double-decker" type, and the extended chimney carried the smoke
and steam sufficiently high to clear the upper storeys to a great extent.
As some recognition of his services to locomotive engineering,
Monsieur Mallet was awarded in 1877 the Fourneyron Prize for
Mechanics by the Institute of France ; and he has also since received
several other prizes and decorations of considerable value and
importance in the engineering world.
Andrade's Three-cylinder Design. In 1875 a French patent was
granted to Monsieur Andrade, with which scheme it is believed that
Monsieur Mallet had something to do, setting forth the use of three
cylinders, one high-pressure and
two low-pressure.
Holt's Designs for Com-
pound Tramway Engines. Two
patents were granted in 1876
to Mr H. P. Holt, a well-known
British engineer, concerned large-
ly with tramway engineering, for
a two-cylinder compound system
intended for tramway locomo-
tives. It is believed that com-
pound tramway locomotives were
actually built according to this
system.
The Struwe Three-cylinder
Design. In 1879 particulars
were published of a three-cylinder
design prepared by Monsieur
Struwe, of the Kolomna Engine
Works (Russia). In this arrange-
ment an open-work piston-rod
framing had to be employed for
the inside high-pressure cylinder,
in order to operate past the lead-
ing coupled axle, the second
coupled axle being driven by all
cylinders.
A curious scheme is covered by a patent of 1881. This suggests
the use of an injector between the high- and low-pressure cylinders
for the purpose of relieving the back pressure upon the H.P. piston
when specially great power is required. Whether this would prove
satisfactory in practice is a moot question.
Mallet's suggested Schemes. In 1879 Monsieur Mallet published
particulars of several suggested schemes for compounding locomotives
with four cylinders arranged in various ways. One of the proposals
related to a tandem arrangement of cylinders, and this was carried
into practice in 1891 on the South- Western Railway of Russia,
according to the instructions of Monsieur Borodine, one of the chief
locomotive officials of the Russian railways, and formed the com-
FIG. 27. Cross Section of Mallet's
first Compound Locomotives.
36
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
mencement of a long series of tandem compound locomotives
employed in Russia, Monsieur Mallet being associated with Monsieur
de Glehn in the design of these engines.
Monsieur Mallet also proposed a three-cylinder system wherein
two low-pressure cylinders are superposed at one side of the engine,
their piston rods being connected to the same crosshead, as shown by
fig. 28. This system, which had for its object to allow of large low-
pressure cylinder volume being employed without the cylinder
projecting unduly from the frames, and which is, therefore, strictly
the equivalent of a two-cylinder system, has never been carried out.
It was also proposed by Mr Lapage in 1889 in connection with
another scheme.
The von Berries first Engines. The Worsdell-von Borries-Lapage
system, with its variations according to the individual practices
of the three engineers whose names are generally placed together
in referring thereto, is the principal and original of two-cylinder
automatic systems wherein the starting valve allows of the use of
u ui
FIG. 28. Proposed Three-cylinder or Double Low-pressure System (1879).
boiler steam in the low-pressure cylinder only until the high-pressure
exhaust attains sufficient pressure for working in the low-pressure
cylinder, which occurs usually after three or four strokes.
The first work was done by Herr von Borries, then in charge of
the locomotives of the Hanover section of the Prussian State
Railways, and was originally applied in 1880 to two small tank
engines. Fig. 29 is a line engraving showing one of these engines.
After extended trial, the system was applied to several other small
engines, and in 1882 to two large goods engines; and during
succeeding years the system was applied to engines of other
railways, since which date locomotives compounded according to the
von Borries system have been applied extensively on the Continent
Worsdell's first Engines. In 1884-5 Mr T. W. Worsdell applied
his system, which corresponds in main features to that of Herr von
Borries, to express locomotives of the Great Eastern Railway, of
which line he was then Locomotive Superintendent. An outline
engraving of one of these engines, which had inside cylinders 18
and 26 in. in diameter, is shown in fig. 30. In the latter year Mr
Worsdell transferred his services to the North-Eastern Railway, on
HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 37
which line these compound locomotives were introduced in large
numbers, eventually to a total of several hundreds of various types
single-driving and four-coupled express engines, six-coupled goods
engines, and six-coupled goods tank engines. At a later date the
Worsdell system was also applied to locomotives of the Belfast
FIG. 29. First von Borries Two-cylinder Compound Engine (1880-1).
Reproduced from Verein Deutsche Ingenieure.
and Northern Counties Eailway of Ireland, and it is curious to
note that Worsdell compound locomotives on this line are among
the last to be introduced in Great Britain, some of them within
the last two or three years.
After a few years of independent work the two gentlemen named
n
FIG. 30. Diagram of first Worsdell Two-cylinder Compound Locomotive,
Great Eastern Railway (1884).
joined forces, as their individual systems corresponded so closely;
and as Mr Lapage, a Westminister consulting engineer, largely
concerned with the design of locomotives for Colonial and South
American railways, was also introducing the Worsdell-von Borries
system, with modifications of his own, the later arrangements have
been patented jointly in the three names, and, except for the early
38 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
work, the system requires to be described as the Worsdell-
von .Borries-Lapage system, in \vhich form it has been applied to
many thousands of locomotives in all parts of the world.
The extremely divergent ways in which the system is estimated is,
however, a fit subject for a few remarks.
On the Great Eastern Railway the whole of the compound loco-
motives were converted to non-compound by Mr J. Holden, who suc-
ceeded Mr Worsdell as Locomotive Superintendent, but not until
that gentleman had conducted further experiments by adapting a
goods engine according to the Worsdell system.
On the North-Eastern Railway, Mr Wilson Worsdell, brother and
successor to Mr T. W. Worsdell, has converted the majority of the
compound engines to non-compound.
In Continental countries, however, the Worsdell- von Borries engines
are still in use in very large numbers, and there have been only a
few instances of their conversion ; in this respect Continental practice
contrasts strikingly with the fate of British engines. For Colonial
and South American railways the system is represented by many
hundreds of engines; and although in many cases compound engines
are not now built, there are other instances of new engines according
to this system which have been quite recently supplied, many of
them designed and built in this country.
The system has also been applied to many engines for use in India,
United States, and other countries, quite independently of any of the
engineers named ; but, as a rule, and in the United States particularly,
the two-cylinder systems employed of an automatic character are
really developments or variations of the Worsdell- von Borries-Lapage
system.
Webb's First Three-cylinder Engines. The late Mr F. W. Webb,
for so many years the well-known Chief Mechanical Engineer of the
London and North-Western Railway, commenced experimenting in
connection with the compounding of locomotives in 1878 by con-
verting an old engine to a two-cylinder compound engine according
to Monsieur Mallet's system, and in 1881 the first of his own
three-cylinder compound engines was placed in service. It will
therefore be seen that to Mr Webb must be credited the honour
of being one of the pioneers of locomotive compounding.
In the original engine, appropriately named "Experiment, "as well
as for over a hundred subsequent engines, the peculiar plan was em-
ployed of using two comparatively small high-pressure cylinders
driving by cranks at right angles one pair of driving wheels, there
being a single large low-pressure cylinder actuating another driving
axle, the two pairs of driving wheels being uncoupled. Moreover,
Mr Webb did not provide any means for admitting boiler steam to
the low-pressure cylinder at starting, the small high-pressure cylinders
being forced to start a train unaided until the low-pressure cylinder
could receive steam from them. This engine is shown in fig. 31,
which has been reproduced from Engineering.
As might be expected, the appearance of the first of these engines
HISTOKY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 39
not only attracted attention from engineers all over the world, but
provided material for one of the most heated controversies which
have ever appeared in the pages of an engineering journal, for letters
from amateur and practical engineers appeared week after week for
several months in the pages of Engineering, the writers endeavouring
to prove and disprove that Mr Webb was altogether wrong, both as
regards his system and as regards the design of the engine. It must
be remembered that in those early days there were very few engineers
who would admit that locomotive compounding could be satisfactory
at all, and the opposition to Monsieur Mallet and to Mr Webb was in
some quarters of an extreme character.
However, Mr Webb disposed of his opponents, who said in effect
that ' ' he did not know his business," by building more and more of his
three-cylinder compound engines, and showing their capabilities in
working the express traffic of the London and North- Western
Railway ; and although the building of these engines has for some
FIG. 31. First Webb Three-cylinder Compound Engine for London and
North- Western Railway (1881). Reproduced from Engineering.
years been discontinued in favour of four-cylinder coupled compound
engines, and Mr Webb's successor, Mr G. Whale, has discontinued
the building of compound locomotives at all, yet the record of the
three-cylinder engines is one of which no railway need be ashamed.
That they might have been improved most engineers will agree,
especially now that the course of years has produced so many other
compound systems, and it may be admitted that the greatest
progress has been made with systems differing radically from Mr
Webb's in nearly all essential particulars ; but the disposition to
belittle the work of Mr Webb, which has been very apparent in
engineering journalism since his retirement under circumstances
which preclude any reply on his part, is both discourteous and
unfair. Mr Webb died in June 1906.
Nearly all the Webb three-cylinder compound passenger engines
have been "scrapped" during 1905-6.
Sandiford's Experiments in India. In 1883 Mr C. Sandiford,
Locomotive Superintendent of the Scinde, Punjab, and Delhi Railway
40
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
of India, experimentally converted two engines, one as a two-cylinder
compound engine and the other as a four-cylinder compound engine.
A simple valve was provided to admit steam to the low-pressure
cylinder in the case of the two-cylinder engine when the high-
pressure crank was on a dead centre, but otherwise no special starting
device was fitted. In neither case were the engines sufficiently
satisfactory to warrant an extension of compounding, though they
did as well as a non-compound engine, and in some cases better.
The Dunbar Tandem System. About the same time an engine
for the Baltimore and Ohio Railroad in America was fitted as a
FIG. 32. First Design of Mallet Articulated Compound Engine (1885).
tandem compound engine according to the Dunbar system, but it
did not prove very satisfactory. It is, however, only fair to note
that at the time of the trials the inventor was ill, and could not give
his personal attention.
The Bousquet Tandem System in France. In 1882-3 Monsieur
du Bousquet introduced a class of tandem compound heavy goods
engines on the Northern Railway of France, which engines have
always done good work, and are still at work, it is believed, unaltered.
This system is described in detail in Chapter IX.
About 1886 or 1887 an engine of the North British Railway was
converted as a tandem compound engine, with all cylinders between
HISTORY AND DEVELOPMENT OF THE COMPOUND LOCOMOTIVE. 41
the frames, according to the Nisbet system. The engine selected
was No. 224, the engine which fell with the Tay Bridge during the
terrible storm of Christmas Eve, 1879. It was stated that the
engine did not give results as a compound sufficiently notable to
warrant extended use of the system, and it was soon after converted
again as a simple engine.
At about the same time two engines were experimentally converted
on the Great Western Railway, one engine having ordinary tandem
inside cylinders, the high-pressure cylinders being placed in front
of the low-pressure cylinders, and in the other case the low-pressure
cylinders were in front, and their pistons had two piston rods which
worked on either side of the high-pressure cylinders, so that each
crosshead had three piston rods connected to it, substantially in the
manner indicated by fig. 15. These experiments again did not
result in further compound locomotives, and the engines were soon
afterwards rebuilt as non-compounds.
Mallet's Articulated System. The Mallet articulated or double-
bogie system was introduced first in 1 887, as described in detail in
Chapter XIII. Fig. 32 is a reproduction of a design prepared by
Monsieur Mallet in 1885.
Brief Review to Date. This period also produced the first de
Glehn four-cylinder compound engine, the Landsee " Asynometric "
system, the Henri four-cylinder system, the Lindner system, the
Sauvage three-cylinder system, and the Swiss three-cylinder system ;
and in 1889-1893 most of the American systems were introduced,
together with various Continental systems, such as the Golsdorf,
Maffei, and others, most of which are specifically referred to in
appropriate chapters.
It is impossible and unnecessary to maintain the subsequent
chronology of locomotive compounding, and the practical develop-
ments (other than schemes not actually employed) are considered
in the following chapters, which relate almost entirely to the modern
compound locomotive.
CHAPTER V.
TWO CYLINDER NON-AUTOMATIC SYSTEMS.
CONTENTS : The Mallet System Worsdell-von Borries-Lapage N on -automatic
System Batchellor System Colvin System Worsdell-von Borries-Lapage
latest System Landsee Asynometric System Mallet Two-cylinder Tandem
System Brunner System Starting Arrangements on Eastern Railway of
France Rogers Non-automatic System Two-cylinder Compound Locomo-
tives (Non-automatic) on the Hungarian State Railway Schenectady Non-
automatic System Vauclain Two-cylinder System The Cooke System
Nadal System The Dultz System Two-cylinder Compound Engines in Italy.
THE systems of this class are the most numerous of those concerned
with the use of two-cylinders only for compound locomotives, and
it is therefore fitting that these should be dealt with first, more
especially as the earliest compound engines those designed by
Monsieur Mallet for the Bayonne and Biarritz Railway in 1876-7
belong to this class. According to all such systems, it is possible
to continue non-compound working after starting, whereas in auto-
matic systems, after two or three strokes, the engine commences to
work compound, quite irrespective of any action on the part of the
driver.
The original work of Monsieur Mallet has already been briefly
reviewed, and the technical details of his work will now be con-
sidered.
The Mallet System. In the first engines a valve of the slide
valve type was located in a casing arranged outside the upper part
of the smokebox, and could be operated from the engine cab by the
driver. This valve covered or uncovered ports which allowed the
high-pressure exhaust to pass either to the low-pressure cylinder or
to the chimney. With it was combined an automatic piston valve,
which, when the slide valve uncovered the port leading to the low-
pressure cylinder, allowed steam to pass at a reduced pressure to
that cylinder.
In engines built immediately afterwards for the Haironville
system of light railways in France, Monsieur Mallet also provided
for the independent adjustment of the valve gears of the two
cylinders, so that the point of cut- off in each could be relatively
42
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
43
varied to balance or adjust the work being done in each cylinder
under varying circumstances.
In applying the system to other engines, which was done to a
notable extent during the next three or four years on the Northern
Railway of Spain, in Russia on the South-Western Railway, and in
a few other instances, the starting valves were slightly modified, but
not to any appreciable extent. In one construction, very similar
to that described in other respects, the slide valve^was itself
employed to control the live steam admission to the low-pressure
cylinder, its upper surface controlling an admission port connected
with a small steam-pipe, the required reduction of pressure resulting
in this case from wiredrawing.
In these later engines the connecting pipe between the high- and
low-pressure cylinders, which constituted the receiver, was lengthened
by being carried round the smokebox, so that the steam became
reheated somewhat before being used in the low-pressure cylinder.
In other engines the starting and intercepting valves were
separated, one valve being placed
on either side of the smokebox.
The starting valve comprises
a small slide valve covering two
ports leading to the receiver, and
on the top of this valve another
slide valve is formed controlling
two ports, one leading to the
atmosphere and the other to a
small pipe connected with the
intercepting valve on the other
side of the smokebox. The
FIG. 33. One Form of Mallet
Intercepting Valve.
valve casing is connected with
the live steam supply to the
intercepting valve, for a purpose
explained in the next paragraph. When the starting valve is moved
by the driver, a port is uncovered so that boiler steam can pass to
the receiver, and at the same time other ports are connected so
that the small pipe mentioned is opened to the atmosphere.
The intercepting valve (fig. 33) consists of two circular valves and
a piston mounted on one spindle. As shown, the valve is in the
position for compound working. Steam enters from the starting
valve by means of the small steam-pipe above mentioned behind the
piston, and by its pressure closes the left-hand valve, which shuts off
communication with the chimney and opens the other valve, so that
steam from the high-pressure exhaust can pass to the receiver, and
thence to the low-pressure cylinder. When the starting valve is
operated for non-compound working, the space behind the piston is
connected with atmosphere as described and the steam supply is cut
off; at the same time boiler steam has been admitted to the receiver
by the starting valve and the right-hand valve therefore closes, the
left-hand valve simultaneously opening to the chimney.
44
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
It will thus be seen that, whereas in the earlier construction it
was the intercepting valve that was controlled directly by the driver,
in the later construction the starting valve was so adapted, the
intercepting valve working automatically.
In another construction a starting cock was employed instead of a
slide valve.
In some cases engines fitted with arrangements for non-compound
working of the kind described were fitted with ordinary pressure-
reducing valves between the starting valve and the receiver. Also,
in some instances, the intercepting valve was adapted to be operated
by the driver simultaneously with the starting valve.
In later years the Mallet types of starting and intercepting valves
have lost their identity in a large measure in the newer designs
FIG. 34. Worsdell-von Borries-Lapage Non-automatic Starting and
Intercepting Valve (Compound Position).
introduced by various locomotive engineers and locomotive building
firms, but they are mostly based on Monsieur Mallet's original
designs.
The Worsdell-von Borries-Lapage Non-automatic System.
After a good many years' employment of compound locomotives
having automatic starting arrangements, as will be described in
detail in Chapter VI., these gentlemen patented in 1892 a con-
struction of automatic starting valve which allowed of an engine
being worked non-compound for a longer period than two or three
strokes ; and this valve, one construction of which is shown in fig.
34, has been employed for later two-cylinder compound locomotives.
The valve case A is formed with a high-pressure exhaust passage
BB 1 adapted to form part of the receiver pipe, and with another
passage C which forms part of the low-pressure exhaust passage.
The piston valve D controls the passage E which connects the
passages B 1 and C ; and the piston valve F, which works in an
TWO-CYLINDER NON-AUTOMATIC SYSTEMS. 45
extension A 1 of the valve casing, controls a boiler steam inlet G.
This inlet may be controlled by a cock or valve operated by hand or
from the reversing gear, or a special regulator valve may be employed
for the purpose, as will be described later. The port A* connects
with atmosphere in order to remove resistance to the movement of
the valve F. The valves D and F are mounted on a rod H having
two diameters as shown, the part H 1 working through a partition A 2
so that live steam cannot flow freely to the low-pressure cylinder
until the valve D is fully opened, at which time the smaller part H 2
of the rod H has passed into the opening in the partition A 2 .
When live steam is admitted through G so as to act upon the
inner end of the valve F, the two valves will be moved automatically
into a position which causes the valve D to close the passage B B 1
and open the passage E so that the cylinders can exhaust separately
to the chimney, and the valve F occupies a position such that the
rod H has moved sufficiently to open an annular passage through
the partition A 2 around the smaller part H 2 of the rod, thus
allowing boiler steam to pass to the low-pressure cylinder for non-
compound working. When the supply of steam to the inlet G is cut
off, the valves D F return automatically to the normal positions
shown, by reason of the greater pressure on the valve D on the side
nearest to the receiver passage B 1 .
To allow of the inlet G being in constant connection with boiler
steam the air-hole A* is dispensed with, and the front end of the ex-
tension A 1 is connected by a pipe G 3 with the steam supply controlled
by a valve I, which can be opened or closed by the driver through
the lever L, and there is also communication with atmosphere, so
that by closing the valve I to steam and opening a passage from
A 1 to atmosphere, steam acts on one side only of the valve F, and by
opening the valve I to steam the equilibrium of pressure on the
valves D F is destroyed, and the said valves move automatically into
the compound position. The arrangement illustrated also provides
for a reduction of the live steam pressure for supply to the low-
pressure cylinder.
Generally, when the inlet G is only connected with steam when
working non-compound, the ordinary regulator valve is provided with
a special port, so that when fully opened, as at starting or when
working hard, steam passes to G and the engine works non-compound,
whereas on partially closing the regulator the steam is cut off from
G and compound working commences. It therefore follows that
with such an arrangement an engine only works non-compound with
the steam regulator fully open or nearly so, whereas when the valve
I is employed non-compound working results entirely at the will of
the driver.
Batchellor System. This system has been largely employed in
past years for engines built by the Rhode Island Locomotive Works,
U.S.A., though, since the amalgamation of this firm into the Ameri-
can Locomotive Company, it has only been used, if at all, when
specially ordered.
46
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
The intercepting valve (shown in figs. 35 and 36) is of the piston
type, having three pistons a b c mounted on one rod, the movement
of which is controlled by a dashpot d, these valves operating auto-
matically according to whether the starting valve e, which is controlled
by the driver through an arm / and rod extending into the cab, is
in position for compound or non-compound working. The pipe i
FIG. 35. General Arrangement Rhode Island (Batchellor) System.
serves for the main steam supply to the intercepting valve ; the pipe
k constitutes the receiver; the port m connects the steam pipe i
with the interior of the valve; the port n connects the interior of
the valve with the pipe h wherein the reducing valve is situated ;
and the port o connects with the low-pressure steam chest. The
FIG. 36. Intercepting Valve Rhode Island (Batchellor) System.
starting valve e connects, when open, the receiver pipe k with the
blast pipe p, and thence with atmosphere for working non-compound.
In operation at starting, the valve e being closed and the regulator
being opened^ steam passes, in addition to its direct passage to the
high-pressure cylinder, along the pipe i and into the intercepting
valve through the port m, where it acts on the piston b. which is
slightly larger than a, moving the whole to the right, and opening a
for steam from m through the port n to the reducing valve h,
TWO-CYLINDER NON-AUTOMATIC SYSTEMS. 47
and thence to the low-pressure steam chest, the steam being pro-
portionally reduced in pressure before use in the low-pressure
cylinder. As soon, however, as the pressure in the receiver becomes
sufficient for compound working, the greater pressure on the receiver
face of the piston c causes the valves to be moved to the positions
shown, cutting off the live steam supply to the low-pressure cylinder,
and opening the port 0, connecting receiver and low-pressure steam
chest.
Thus far it will be seen that the intercepting valve operates auto-
matically, and were no starting valve employed the system would be
an automatic one, not allowing of extended non-compound working.
By opening the starting valve e, which is of the "hit-and-miss"
type, the high-pressure exhaust is allowed to pass to the blast pipe,
and as long as this is permitted, the absence of pressure in the
receiver causes the intercepting valve to remain in position for non-
compound working. Consequently, although an engine fitted accord-
ing to this system always starts non-compound, the driver can also
continue non-compound working as long as desired.
The system has been applied without the starting valve, and it
then belongs to the automatic class, but in most cases the starting
valve is employed. Engines fitted according to this system (with
the starting valve) have been used for service on the Brooklyn
Elevated Railway (New York), than which it would be difficult to
find a more arduous task, for such work entails very frequent
stopping and starting, and rapid accelerative power is absolutely
necessary.
The Mellin System. This system has been principally employed
for engines built by the Richmond Locomotive Works (U.S.A.),
another firm now embodied in the American Locomotive Company ;
but it has also been fitted for some Continental locomotives, and this
system stands almost alone among American compound systems in
having been employed for engines outside of America, and not of
American design and build.
[n general operation the Mellin system is very similar to the
Batchellor system already described, though it also corresponds to
a great extent with some of Monsieur Mallet's valves. A general
construction as used in America is shown in fig. 37.
The space / connects with the high-pressure exhaust and constitutes
part of the receiver, and its communication with the passage h to the
low-pressure cylinder is controlled by the main intercepting valve g,
which valve is automatically closed at starting by boiler steam
from o acting on the small annular area at the right-hand end of
the piston I mounted as a sleeve upon the valve spindle. Live steam
at a reduced pressure then passes from o through the annular passage
opened when the piston I moves to the left with the valve g. As
soon as the pressure in the receiver becomes sufficient, the valve g
opens, cutting off the live steam supply from o, and the engine
works compound.
Thus far the valve is automatic in its operation, but to allow of
48
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
compound working being maintained a spring valve b is fitted, which
valve may be operated by levers and rods from the cab, or, as shown,
by steam admitted at d behind the small piston c. When the valve
b is opened the H.P. exhaust from / can pass away via a to the
blast pipe, and as there is then no receiver pressure the valve g
remains closed. For the purpose of ensuring prompt closing of the
FIG. 37. Mellin Starting and Intercepting Valve.
valve g it is provided with a perforated piston u. Communication
with exhaust is allowed through the perforations in u until that
valve has moved to the left, when passage around the valve is also
permitted. A dashpot cylinder is fitted at s.
The Colvin System. This system, again, is one introduced and
employed by an American firm (the Pittsburgh Locomotive Works),
which is now absorbed in the American Locomotive Company. In
FIG. 38. Colvin Starting and Intercepting Valve (Pittsburgh
Locomotive Works).
this case (fig. 38) the controlling pistons a b are moved directly
by the driver through the rod c, there being, however, an automati-
cally acting live steam admission valve d. Boiler steam is admitted
through the passage e, controlled by the valve d. The passage /
communicates with the receiver, g is the passage from the high-
pressure cylinder, and h the passage for the high-pressure exhaust
when the engine is working non-compound. When the valve is
moved to the right, boiler steam enters from e past the valve d,
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
49
which opens of itself to the receiver, and thence to the low-pressure
cylinder. At the same time the high-pressure exhaust passes from
g to h.
On moving the valves a b to the left, so that the parts occupy
the positions shown, the high-pressure exhaust is diverted to the
receiver, and thence to the low-pressure cylinder, and the live steam
supply through d is cut off, that valve being forced on to its seating
by the valve a. The valve d is of differential construction, so that
it acts as a reducing valve whereby the boiler steam for use in the
low-pressure cylinder is appropriately reduced in pressure.
Ivatt's Starting and Intercepting Valve. In 1896 Mr H. A.
Ivatt, now Locomotive Superintendent of the English Great Northern
Railway, but then occupying a similar position on the Great
Southern and Western Eailway of Ireland, experimented with an
engine having a combined starting and intercepting valve of the
FIG. 39. Improved Non-automatic Starting Valve "Worsdell-von Borries-
Lapage System.
composite piston type, but nothing further was done with this
system.
Messrs Worsdell, von Borries, and Lapage's latest form of
Starting and Intercepting Valve. The valve shown in fig. 39
represents the latest form of starting and intercepting valve intro-
duced by these gentlemen since 1900. As can be seen, it is very
similar in general character to many others of the valves which
have been described, but it is somewhat notable for embodying
almost the acme of simplicity in connection with such valves,
especially as it combines the purposes of a starting, intercepting,
and reducing valve.
The hollow piston valve 1 works within a casing having ports and
openings connecting as follows :
At 4 with the receiver, and thence with the low-pressure cylinder ;
at 5 with the blast-pipe or atmosphere ; at 6 with the exhaust port
of the high-pressure cylinder; and at 10 with the main steam
supply. The spindle of the valve 1 has an enlarged portion 15, part
of which constitutes a second valve co-acting with the valve 1.
4
50 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
With the ports in the position shown the high-pressure exhaust
from 6 is connected with the blast pipe or atmosphere through 7,
communication with the low-pressure cylinder through 4 being cut
off, and boiler steam from 10 is allowed to enter through the
annular passage round the spindle 9, as permitted by the position
then occupied by the part 15, the arrangement being such that the
purpose of a reducing valve is served, and passes through the
openings 11 to the hollow of the valve 1, and thence to the low-
pressure cylinder.
When there is no pressure in the receiver the boiler steam
entering forces the valves to the positions shown if they do not
already occupy those positions, but as soon as the receiver pressure
becomes sufficient they move, if permitted otherwise, to the left, so
that the high-pressure exhaust is connected with the receiver, and
the live steam supply cut off owing to the excess of pressure of
the receiver steam on the end of the spindle 15; but this may be
prevented when a lever, of which the end is shown in section at
13, is so operated from the engine cab that the spindle 9, 15 is held
in the position represented, and therefore the engine works non-
compound until the lever 13 is moved to allow the spindle 9, 15 to
move to the left so that compound working commences. It will
therefore be seen that the driver has full control of compound or
non-compound working, and the change from non-compound to
compound is assisted when there is a working pressure in the
receiver.
This construction of valve has been also applied by Herr von
Borries for four-cylinder compound locomotives.
The Lands6e Asynometric System. This system is one of the very
few two-cylinder systems noted here that present features of difference
other than those due to variations in the construction and arrange-
ment of starting and intercepting valves, but which otherwise relate
to systems which belong to one or other of the three main classes,
which may be described as the Mallet, the Worsdell-von Borries-
Lapage, and the Lindner systems. The system under notice has for
object to enable an engine having two cylinders of equal size to be
worked either as an ordinary simple engine or as a compound engine.
It was experimentally tried on the Northern Railway of France in
1885, as applied to a small tank engine, and afterwards to four
engines belonging to the Dutch State Railways, but the writer has
no information of further use.
As the cylinders were of equal diameter, the inventor arranged that
the reduction of pressure for low-pressure use when working compound
should be compensated for by so adjusting the valve gears, which
were independently adjustable, that the steam was cut off early in
the stroke in the high-pressure cylinder and late in the low-pressure
cylinder, so that the total work done in each cylinder should be
approximately equal. In the case of one of the Dutch engines, how-
ever, though both the cylinders had the same diameter, the low-
pressure piston had a stroke double that of the high-pressure piston,
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
51
A Mallet Two-cylinder Tandem System. This system, though
never carried into practice, is a somewhat curious project designed
by Monsieur A. Mallet and Herr A. Brunner, Chief Engineer of the
well-known firm of I. A. Maffei of Munich. As will be seen from
fig. 40, a high-pressure and a low-pressure cylinder are arranged
tandem fashion between the frames, and the two piston rods (which
are quadrupled outside the cylinders) drive in opposite directions, the
connecting rods operating backwards on to separate cranked axles,
the two pairs of driving wheels being coupled by outside rods. For
52
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
this scheme one or other of the various starting valves already
described would be employed.
The Brunner System. This system, though never carried out, was
originally schemed out by Herr Brunner about 1889 as the result of
FIG. 41. Starting Mechanism for Brunner System.
extensive experience with other engineers' (notably Monsieur Mallet's)
systems ; and, so far as the writer is aware, it has never hitherto
been made public, though it possesses features of interest.
The two cylinders (fig. 41) are connected by a pipe having two
valves adapted to be operated together, so that when one is open the
TWO-CYLINDER NON-AUTOMATIC SYSTEMS. 53
other is closed, and vice versa, by means of a rocking lever, which is
rocked through the levers shown from a rod extending into the cab,
where it can be operated by the driver ; one of these valves (A)
controls connection from the high-pressure exhaust to the blast pipe,
and the other (B) controls the connection of the low-pressure cylinder
with the receiver pipe. Alongside the valve B is a valve C, operated
simultaneously with the rocking lever, and therefore correspondingly
with the valves A B, whereby, when B is closed to receiver, boiler
steam can pass from the pipe D to the low-pressure cylinder. In
connection with this system it has been recently proposed to adapt
the valve C so that, under the control of the reversing gear, it will
act as a variable pressure-reducing valve, whereby the pressure of
boiler steam supplied to the low-pressure cylinder is so regulated as
to equalise the work done in the two cylinders according to the cut-
off ratio employed for the high-pressure valve gear.
Starting Arrangements employed on the Eastern Railway of
France. About ten years ago several two-cylinder compound loco-
motives were fitted on the Eastern Railway of France, with starting
mechanism which comprised three valves arranged side by side in
different transverse planes, all three valves being operated by the
oscillation of a single spindle connected by levers with an operating
handle in the driver's cab. One of these valves was a spring valve
for allowing boiler steam to pass from the high-pressure steam chest
to the low-pressure cylinder. The second valve, of the flap type, was
operated through a slotted curved link, which permitted it to open
irrespectively of the operating mechanism if the high-pressure
exhaust pressure exceeded that in the receiver, and its purpose was
to separate the high-pressure exhaust from the receiver when work-
ing non-compound. The third valve controlled the passage of the
high-pressure exhaust steam to the blast pipe or to the low-pressure
cylinder.
The Rogers Non-automatic Starting Mechanism. This mechan-
ism has been applied to a large number of locomotives built by the
Rogers Locomotive Works for various American railways. The
general arrangement is shown by fig. 42, the parts being shown in
position for non-compound working as at starting.
The starting valve casing contains a small slide valve a adapted
for operation by means of levers extending into the driver's cab, and
when in the position shown, live steam can pass from the pipe b
through c, and fchen by the small pipe d to the intercepting valve
casing e, where it forces the piston/ to the right so that the port g is
uncovered and steam can pass from b into the interior of the piston
/, and thence, as shown, to the receiver, for use in the low-pressure
cylinder. At the same time the piston h is moved on to its seating
i, to close communication between the exhaust of the high-pressure
cylinder and the receiver ; and the exhaust pressure causes the valve
k to move to the right, to open communication with the blast pipe or
atmosphere.
To change to compound working, the valve a is moved so that
54
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
stearn can pass from c round the outside of the valve to the pipe m
leading to the further side of the valve k. At the same time the
space e is placed in communication with atmosphere through the
interior of the valve a and the pipe n, and as the pressure upon the
valve / is removed, the intercepting valve h moves to the left, and
with it the valve /, closing the port g and opening communication
between the exhaust of the high-pressure cylinder and atmosphere,
while the pressure of the steam through m moves the valve k to close
the passage to the blast pipe or atmosphere.
The valve / acts as a reducing valve, whereby the pressure of steam
FIG. 42. Rogers Non-automatic Starting Mechanism.
entering through the port g when working non-compound is reduced
in pressure before it passes to the receiver as above described.
Two-cylinder Compound Locomotives (Non-automatic) on the
Hungarian State Railways. On the Hungarian State Railways
compound locomotives are fairly numerous both with two cylinders
and with four cylinders arranged tandem (see Chapter IX.), but
comparatively little is known generally concerning the systems
employed, and therefore particular interest attaches to this section
of our subject, more especially as many of the two-cylinder engines
concerned are among the latest built of this character, and are,
moreover, notable machines from the point of view of dimensions,
power, and general design.
The starting valves employed for some of these engines are of the
non-automatic type, thus following the practice initiated by Monsieur
TWO-CYLINDER N ON- AUTOMATIC SYSTEMS.
55
Mallet, but in other cases they are of the automatic type, wherein
non-compound working results only at the moment of starting. The
automatic valves are considered in Chapter VI.
According to the arrangement shown in fig. 43, the parts being
represented in the positions they occupy during compound working,
and the non-compound positions being indicated by dot-and-dash
lines, at starting or at times when great power is required the
driver moves the lever a so that the piston valve b uncovers a port
whereby boiler steam passes from the pipe c to the pipe d leading to
FIG. 43. Non-automatic Starting and Intercepting Valve Hungarian
State Railways.
the receiver, and thence to the low-pressure cylinder, and at the
same time the double (and consequently balanced) pistons ee l are
moved so that steam is prevented from passing from the high-
pressure cylinder through the pipe /, and is directed to the pipe g
leading to the blast pipe. For the purpose of returning the parts to
the compound positions, live steam can be admitted at h by a small
cock so as to act on the piston e l and force it and the piston e to the left.
The New Schenectady Non-automatic System. This system
is now the standard for locomotives built by the American Loco-
motive Company, and has largely superseded the various systems
already dealt with, which were associated with particular firms now
56 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
incorporated in this company. As will be seen, it corresponds in
many respects with the original Schenectady (Pitkin) automatic
system referred to in the next chapter. Fig. 44 shows the con-
struction of starting and intercepting valve now employed, and fig. 45
shows the location of that valve and the smokebox arrangement.
For starting non-compound, as shown in fig. 44, the handle of the
three-way cock in the cab is moved by the driver so as to admit
pressure through the pipe D against the piston A, forcing it and the
valves B and C to the position shown. As the regulator is opened,
steam is admitted directly from the boiler into the passage E, forcing
the intercepting valve into the position shown; thence the steam
passes through the intercepting valve, by the ports K and the
passage G, through the reducing valve to the low-pressure steam
chest ; at the same time steam from the boiler is admitted directly
by means of the steam pipe to the high-pressure steam chest. The
exhaust from the high-pressure cylinder passes to the atmosphere by
means of the receiver passage H and the separate exhaust valve B.
Steam from the low-pressure cylinder is exhausted directly to the
atmosphere.
Having started simple, to change to compound the handle of the
three-way cock in cab is turned so that pressure is released from the
piston A. The separate exhaust valve will then be closed by the
spring I. The pressure in the receiver, due to the exhaust from the
high-pressure cylinder, will rise and force the intercepting valve to
the left, thereby opening the passage for the exhaust steam from
the high-pressure cylinder, through the receiver, to low-pressure
steam chest. The movement of the intercepting valve to the left
also closes the passage G, thereby shutting off the admission of
steam directly from the boiler to the low-pressure steam chest.
When starting compound the separate exhaust valve is left closed,
and as the regulator is opened, the steam pressure in the passage E
will force the intercepting valve to the right or to the closed position ;
at the same time steam directly from the boiler will be admitted
to low-pressure steam chest through ports K and passage G. The
high-pressure cylinder will exhaust into the receiver until the
pressure is sufficient to force the intercepting valve to the left, when
the engine will work compound. The change to compound working
takes place at from one-half to three-quarters of a revolution of the
driving wheels.
With the engine working compound, if the engineer wishes to run
the engine simple to prevent stalling on a heavy grade, the handle
of the three-way cock should be placed in same position as for
starting simple. This opens first the small valve C, and then the
separate exhaust valve. The valve C relieves the pressure, and thus
permits the main valve B to be operated more easily. As soon as
the separate exhaust valve is open, the pressure in the receiver drops
and the intercepting valve is forced against the seat to the right by
means of the pressure in chamber E, and the engine works simple as
before.
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
57
58
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
Some recently built compound locomotives are equipped with
by-pass valves connecting the ends of the cylinders to allow free
air passage when running with steam off.
The Vauclain Two-cylinder System. The system under notice
is a development of the earlier Vauclain two-cylinder system con-
sidered in Chapter VI. Figs. 46 and 47 indicate the principal
features of the starting arrangements employed, the figures showing
FIG. 45. General Arrangement New Schenectady Non-automatic System.
respectively the non-compound and the compound positions of the
ports. Fig. 48 shows the cylinder and smokebox arrangements.
A is a double-piston intercepting valve, located in the cylinder
casting of the high-pressure cylinder, the movement in one direction
being controlled by a spring, and in the other direction by the
steam pressure ; C is a reducing valve, similarly operated by a spring
and by the steam pressure. This valve serves to admit live steam
to the receiver at a reduced pressure when the engine is working
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
59
F IG . 46. Vauclain Two-cylinder Compound. Position of Valves when
working Single Expansion.
FIG. 47. Vauclain Two-cylinder Compound. Position of Valves when
working Compound.
60
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
non-compound. When working compound this valve automatically
closes. The steam for controlling both these valves is supplied
through the pipe D from an operating valve in the engine cab.
When not permanently closed by pressure in the pipes D, the
reducing valve C is operated automatically by the pressure in the
receiver. To this end the port E is provided, communicating with
the receiver and the space in front of the reducing valve; as the
FIG. 48. Cylinder and Smokebox Arrangement Vauclain
Two-cylinder System.
pressure rises, the steam acts on the large end of the reducing valve,
causing it to move backward and close the passage H, through
which steam enters the receiver, and thus prevent an excess pressure
of steam in the low-pressure cylinder. Poppet valves F and G are
placed in connection with the port E, one to prevent the escape of
steam from the receiver to the pipe D when the locomotive is
working single expansion, and the other to close the passage from
pipe D to the receiver when working compound.
Normally the lever of the operating valve in the cab is in the
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
61
position marked "simple." In this position no steam is allowed to
enter the pipes D, and no pressure will be exerted on the intercepting
and reducing valves in opposition to the springs, and they will
assume the positions shown in fig. 46. The ports of the intercepting
valve A stand open to receive the exhaust steam from the H.P.
cylinder and deliver it through the passage B to atmosphere. The
reducing valve C is open, admitting live steam through passage H
to the receiver, and thence to the L.P. cylinder.
For working compound, steam is admitted by operating the driver's
valve to the pipes D to the valve chambers W and C', changing
the valves A and C to the positions shown in fig. 47. The H.P.
exhaust is then diverted to the receiver, and the admission of live
steam to the receiver is stopped.
This system has been employed for a large number of locomotives
built at the world-famed Baldwin Works, Philadelphia, though it
^d ^
FIG. 49. Cooke Starting and Intercepting Valve (Compound Position).
has now been largely superseded by four-cylinder systems introduced
by the same firm.
The Cooke System. This system has been associated with the
Cooke Locomotive Works, but has been discontinued, unless specially
ordered, since the amalgamation of this firm in the American
Locomotive Company. However, as a good many quite modern
engines have been equipped with the Cooke starting mechanism,
brief reference is necessary.
Figs. 49 and 50 are diagrammatic views showing the main features
of the Cooke intercepting valve, one figure representing the position
when the engine is working compound, and the other figure showing
the non-compound positions.
The two piston valves shown are adapted to be closed together,
as shown in fig. 50, for starting, by the admission of boiler steam
through a reducing valve controlled by the driver to the spaces
(small cylinders) on their outer sides through the pipes shown.
This movement brings the ports in the pistons in communication
with the main pipe leading to the receiver, so that the reduced
pressure steam is enabled to pass into the receiver for working in
the low-pressure cylinder. Usually the driver's valve is connected
62
LOCOMOTIVE COMPOUNDING AND SUPEEHEATING.
with the reversing gear, so that it is only when full forward or
backward gear is being employed that steam can pass to operate
the intercepting valves, and consequently, as soon as the engine is
under weigh and the reversing gear is "linked up," the intercepting
valve is moved to the compound position (fig. 50). In other cases
the auxiliary steam valve is controlled by the driver independently
of the reversing mechanism.
For engines equipped according to this system a cut-off lever is
usually fitted in the driver's cab, whereby the travel of the low-
pressure slide valve can be varied independently of the high-pressure
slide valve travel to equalise the work on the two sides of the engine.
The Nadal System on the State Railways of France.
Although France is essentially a country of four-cylinder compound
locomotives, there are a few two-cylinder engines on several railways,
notably the Eastern and Southern (Midi) lines ; but the only very
recent development of this method of compounding is found in the
FIG. 50. Cooke Starting and Intercepting Valve (Non-compound Position).
conversion of some engines of the State Railways into two-cylinder
compound engines, according to designs prepared by Monsieur
Nadal.
These engines are fitted with double piston valves to each cylinder,
one for controlling admission and the other for controlling exhaust,
the two piston valves being located side by side above each cylinder,
and operated by the same valve motion.
Figs. 51 and 52 show respectively the arrangement of valves and
steam connections on the two sides of the engine.
To enable the engine to be operated with boiler steam in the low-
pressure cylinder, a slide valve working in a casing a, fixed upon the
side of the smokebox (fig. 53), is adapted to be operated by the
driver so as to admit steam to one end or the other of a small
cylinder 6, the piston of which operates by its movement a valve
c, which diverts the high-pressure exhaust steam to the blast pipe
instead of to the receiver pipe when working non-compound. At
the same time boiler steam is admitted through a reducing valve to
the receiver on the low-pressure side of the engine, so that the
reduced pressure steam can work in the low-pressure cylinder.
TWO-CYLINDER NON-AUTOMATIC SYSTEMS.
63
It is stated that this system has proved very satisfactory in
practice, and a number of engines are now in use according
thereto. One of these engines was exhibited at the Liege Exhibi-
tion of 1905.
The Dultz System. This system is a development of the earlier
work of Monsieur Mallet in connection with Russian locomotives;
FIG. 51. High-pressure Cylinder and Connections Nadal System.
it is employed somewhat extensively in Russia, and to a limited
extent in Germany and the Scandinavian countries.
Fig. 54 illustrates the starting and intercepting arrangements
employed for such engines.
The intercepting valve consists of three pistons governing the
passage of the high-pressure exhaust steam to the receiver, or to
64
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
the blast pipe, for compound or non-compound working as the case
may be. As shown, the H.P. exhaust can pass from a to the
pipe b leading to the blast pipe, while boiler steam, admitted by
FIG. 52. Low-pressure Cylinder and Connections Nadal System.
the valve c under the driver's control, enters at d and passes by
the passage e to the receiver, and thence to the low-pressure cylinder.
For working compound the piston valves are moved (by the pressure
of the H.P. exhaust upon the slightly larger area upon one side of
the middle piston) as soon as boiler steam is shut off at c and the
TWO-CYLINDEK NON-AUTOMATIC SYSTEMS
65
passage b closed, and a passage opened from a to e so that the
H.P. exhaust can pass to the receiver. It will be seen that the
intercepting valve is automatic in action, the pistons occupying
one position or the other according to whether steam is admitted
through the valve c or not.
Two-cylinder Compound Engines in Italy. In Italy there is a
considerable number of two-cylinder compound engines of various
FIG. 53. General Arrangement Nadal System.
types, some of them being notable engines both as regards express
passenger and heavy mountain service.
The starting mechanism usually employed comprises a long
rotatory, cylindrical, hollow valve, mounted in a casing above the
high-pressure cylinder, this valve having ports whereby the high-
pressure exhaust is diverted to the blast pipe for starting, and boiler
steam is supplied to the pipe connecting the two cylinders, which
5
66
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
also constitutes the receiver for working in the low-pressure cylinder.
The arrangement is somewhat similar to that employed by Monsieur
de Glehn, as described in Chapter XII. in reference to four-cylinder
engines.
CHAPTER VI.
TWO-CYLINDER AUTOMATIC SYSTEMS.
CONTENTS : The Worsdell-von Borries-Lapage Systems Mr Worsdell's Practice
Herr von Berries' Practice Joint Practice Automatic Starting and
Reducing Valves for Hungarian State Railway Systems The Schenectady
(Pitkin) System The Vauclain Automatic System The Dean System The
Player System The Rogers Automatic System.
As already explained, most of the systems of this class are related
to or constitute developments of the original designs of starting
mechanism first introduced by Herr von Borries in Germany in 1880,
by Mr T. W. Worsdell in England in 1884-5, and by these gentlemen
in conjunction with Mr Lapage in later years. It will therefore be
in order that the arrangements associated with their work shall first
receive consideration.
The Worsdell - von Borries - Lapage System. The early work of
each of these engineers possesses a strong family likeness, and as
they have been associated to a great extent in their later designs, it
will be convenient to consider the various types of starting mechanism
introduced by them, either in conjunction or individually, at the same
time.
Mr WorsdeWs Practice. Fig. 55 is a cross section through the
smokebox of an early Worsdell engine, and fig. 56 shows the arrange-
ment and construction of starting mechanism, a is the steam pipe
leading to the H.P. steam chest; b the pipe leading from the H.P.
exhaust to the L.P. steam chest, which constitutes the receiver and
is carried round the smokebox to provide the required receiver
capacity and for slight reheating of the steam ; c is the blast pipe ;
d an intercepting valve casing interposed in the length of the receiver
pipe ; e the starting valve ; and / the boiler steam supply pipe for
the starting valve.
The starting valve/ comprises a small spring-loaded piston, which
can be moved off its seating by the rod g, which extends into the
driver's cab so that the driver can operate it to open or close a port
which leads to the pipe h connecting with the intercepting valve
chamber d.
The intercepting valve is a flap valve mounted on a spindle, which
67
68 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
FIG. 55. General Arrangement first employed Worsdell System.
FIG. 56. Starting and Intercepting Valves Worsdell System (early Form).
TWO-CYLINDER AUTOMATIC SYSTEMS.
69
extends outside the smokebox, where it is fitted with au arm i
engaging in the slotted end & of a rod connected to the small piston I.
The arrangement is such that when the driver opens the starting
valve, steam at boiler pressure acts upon the small piston I and moves
it, thereby lifting the intercepting valve and closing the passage
between the H.P. and L.P. cylinders. At the same time, by the
uncovering of the small port before mentioned, steam is admitted to
the pipe h and thence to the pipe p below the intercepting valve, thus
allowing boiler steam to pass to the low-pressure cylinder. After
two or three exhausts from the H.P. cylinder the pressure in the
receiver becomes sufficient to open the intercepting valve; con-
sequently the small piston / is moved to cut off the live steam to the
L.P. cylinder, and the engine works compound thereafter. It
therefore follows that, with this arrangement, although the driver
can operate the starting valve at any time, its operation is of very
Fio. 57. Early Form of Starting and Intercepting Valves Von Borries
System (early Form).
short duration, and non-compound working can only result when the
pressure in the receiver is less than that resulting from the use of
boiler steam (at a reduced pressure owing to wiredrawing) in the low-
pressure cylinder.
Herr von Homes' Practice. Fig. 57 shows a contemporary style
of starting and intercepting valves introduced by Herr von Borries ;
the strong family likeness between the two valves will be apparent
on inspection. The valve A, placed in the passage between the
receiver pipe and the low-pressure cylinder, is closed before starting
by means qf a rod extending to the driver's cab, thus closing com-
munication between the two cylinders. At the same time the
valve C has moved from off its seating, so that boiler steam entering
at B from a small pipe connected thereat passes through the annular
space formed by the reduced portion of the valve spindle, and can
pass to the low-pressure cylinder. As soon, however, as the pressure
in the receiver due to a few exhausts from the H.P. cylinder rises
70
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
sufficiently, the valve A opens automatically against the pressure of
steam behind it, and as, at the same time, the valve C closes on to
its seating, the engine is forced to work compound.
In many of the von Borries arrangements the intercepting valve
is of the disc type.
Fig. 58 shows a further form of von Borries valve as employed
in the earlier years, but which has also been used more recently.
In this case boiler steam is supplied by the pipe a to the chamber b,
from which it passes by means of a passage (not shown) into the
annular space formed by the reduced portion of the valve spindle c.
When the intercepting valve d is closed the small ports e e are un-
covered so that the steam can pass to the low-pressure cylinder, but
as soon as the valve d opens automatically in the manner already
described the ports e e are closed and the engine works compound.
The auxiliary piston / works in a cylinder g, to which live steam is
FIG. 58. Early Form of Starting and Intercepting Valve Von Borries System.
supplied, and operates to ensure that the valve d is either fully open
or fully closed. When the valve d is closed steam acts on one side
of the piston / so that it tends to press the valve against its seating,
but when the valve d is opened the piston moves past the steam
admission pipe so that the pressure comes upon its other face.
A further construction of the von Borries valve is shown in fig. 59.
A small piston / is fitted which works in a cylinder g, and the top
side of the piston is connected by the small passage shown with the
receiver space ; a live steam pipe h leads to a small cylinder i, wherein
the end of the valve spindle k forms a piston. The object of this
arrangement is to ensure the starting of the engine when the high-
pressure crank is on a dead centre. The live steam then lifts the
intercepting valve d, and as the spindle If rises high enough to
uncover the small passages II steam can pass to the low-pressure
cylinder. When the receiver pressure becomes sufficient the valve
d tends to open, and this is assisted by the pressure of receiver steam
on the piston/, which has a greater area than the end of the valve
TWO-CYLINDER AUTOMATIC SYSTEMS.
71
spindle A 1 , which is subjected to boiler steam pressure, so that the
opening of the valve d is ensured.
FIG. 59. Von Borries System Further Construction of Valve.
FIG. 60. Recent Design of Starting and Intercepting Valves Worsdell-
von Borries-Lapage System.
Joint Practice. A form of valve which is illustrative of Worsdell-
von Borries-Lapage's recent practice is represented in fig. 60, this
72
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
design being employed for engines supplied for service in the
Argentine Republic in 1889.
The two small plungers a a constitute together the starting
valve. Boiler steam passes by the pipe b to the passages cc,
where it acts upon the ends of the plungers a a to cause the
intercepting valve d to close against its seating. At the same time
FIG. 61. General Arrangement of Starting Mechanism Hungarian
State Railways.
the ports e e are uncovered by the plungers a a so that boiler steam
can pass into the pipe connecting with the low-pressure cylinder, but
as soon as the receiver pressure becomes sufficient the valve d is
moved back and the ports e e are closed so that the engine works
compound.
It will be noticed that in the various constructions of starting
valves described in the foregoing paragraphs two classes are included,
for the valves in some cases require to be operated originally by the
TWO-CYLINDER AUTOMATIC SYSTEMS.
73
driver, though compound working results automatically after a few
strokes, while in other cases the valves work wholly automatically.
The admission of steam to the auxiliary passages, by the pres-
sure of which the intercepting valve is closed and boiler steam
allowed to pass to the low-pressure cylinder, is effected by means
FIG. 62. General Arrangement of Starting Mechanism Hungarian
State Railways.
of an auxiliary steam passage opened when the ordinary regulator
is opened.
Owing to the larger diameter of the low-pressure cylinder, it is
advisable, in supplying boiler steam thereto for starting, to reduce
its pressure somewhat ; with the arrangements above described it is
found that in passing through the small passages it becomes wire-
drawn sufficiently to obtain this result.
Automatic Starting and Reducing Valves for Locomotives of
the Hungarian State Railway . As already mentioned, two-cylinder
74
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
compound engines are fairly numerous on the Hungarian State
Railways, and we now describe the various types of automatic
FIG. 63. Intercepting Valve Hungarian State Railways.
starting valves employed for these engines, the non-automatic valves
having been dealt with in Chapter V.
Figs. 61 and 62 indicate the general arrangement of the starting
apparatus employed for engines of one class, and figs. 63 and 64
show the two component parts thereof on a larger scale.
FIG. 64. Starting Valve Hungarian State Railways.
At starting, the driver moves the lever a (fig. G4) through a long
rod extending into the cab so that it occupies the position shown
in dot-and-dash lines. This movement causes the two valves b c to
TWO-CYLINDER AUTOMATIC SYSTEMS. 75
move so that, in the one case, the valve b opens communication
between the live steam supply and the starting apparatus shown in
fig. 63, where it acts on the piston / and forces it to the position
shown in full lines. As a result, the large piston g mounted on the
same spindle is moved so that it closes the port h leading to the
receiver, and thence to the low-pressure cylinder. As soon, however,
as steam arrives through i from the high-pressure cylinder the
piston g is forced to the left, thus opening communication from
the H.P. to the L.P. cylinder.
In the other case, the valve c at starting opens communication
between a live steam supply pipe j connected with the steam dome
through small openings in the valve c, and thence through the small
port k to the receiver through m, the steam being reduced in pressure
by wiredrawing.
This apparatus is only intended to be operated for about half a
revolution of the wheels, but as the valves b c have to be closed by
the driver, the admission of boiler steam to the receiver through m
can take place for a somewhat longer time, though it is not usually
desirable to allow this to continue for more than a few strokes.
The starting apparatus just described is also employed for tandem
compound engines (see Chapter IX.).
Figs. 65, 66, 67, and 68 represent the construction of starting
apparatus employed for other two-cylinder engines.
The valve a is operated by the driver through a rod extending
along the boiler and having a crank connected to the valve rod, and
this valve allows boiler steam to pass to the combined intercepting
and reducing valve b. The live steam thus admitted enters below
the valve b, which is of the disc type and lifts it so that it closes
communication between the two cylinders, and the boiler steam,
reduced in pressure, passes to the receiver. As soon, however, as
there is exhaust pressure from the H.P. cylinder, the valve b is forced
down and the engine works compound. The driver closes the valve
a soon after starting.
The arrangement shown in fig. 68 is employed when there are
two low-pressure cylinders, as in 'articulated' Mallet engines (see
Chapter XIII.).
The Schenectady (Pitkin) System. This system is one of the
principal of the American automatic systems, and has been applied
to many engines built by the well-known Schenectady Locomotive
Works, though it is now largely superseded by a new Schenectady
system which is not automatic, the latter system being now the
standard for engines built by the American Locomotive Company,
unless one of the other automatic or non-automatic systems con-
nected with the various works of this important amalgamation firm
are specially ordered. We are concerned, however, with the older
automatic system, the more recent non-automatic system being
described in Chapter V. In fig. 69 the valve is shown in the non-
compound starting position.
As shown, the piston valves a b close the passages cd so that
76
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
communication is closed between the receiver and the low-pressure
cylinder, though a small passage e permits boiler steam to pass
through a port formed in the piston a to the low-pressure steam
chest. The small port / is connected past a reducing valve with
FIG. 65. Starting Mechanism Hungarian State Railways.
a live steam supply, whereby steam enters the space g, and thence
passes through the passage e as already mentioned.
At the right-hand end of the piston b the receiver pressure is able
to press upon the piston so that as soon as there is pressure in the
receiver from the high-pressure exhaust the valves a b are forced to
the left, thus opening communication between the receiver and the
low-pressure cylinder, while the valve a at the same time closes
TWO-CYLINDER AUTOMATIC SYSTEMS.
77
the port / so that the live steam supply is cut off. A dashpot
cylinder i is fitted to regulate the speed of movement.
\
\
FIG. 66. Driver's Starting Valve-
Hungarian State Railways.
FIG. 67. Intercepting Valve-
Hungarian State Railways.
The Vauclain Automatic System. This system, introduced by
the well-known Baldwin Works of Philadelphia, U.S.A., has also
FIG. 68. Intercepting Valve Hungarian State Railways.
been superseded for present practice by a non-automatic system, but
it has been employed for a number of locomotives, many of which
are still in service.
78
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
The starting valve, fig. 70, is located close to the high-pressure
cylinder, and comprises a reducing valve, which, when the pressure
in the receiver is less than that on the live steam side of the valve
(which is exposed to the steam pressure in the high-pressure steam
FIG. 69.
-Starting and Intercepting Valves (early Form) Schenectady
(Pitkin) System.
chest), automatically opens to allow steam to pass to the receiver
for starting, or when the pressure in the receiver falls below that
required for work in the low-pressure cylinder.
In the smokebox is an automatic intercepting valve, comprising a
FIG. 70. Vauclain (Baldwin Works) Automatic System.
vertically moving hollow piston working in a casing, the upper
part of which, above the piston, communicates with the atmosphere,
while the lower portion of the hollow piston closes the receiver
passage, unless there is sufficient pressure from the high-pressure
exhaust to lift the piston, which is of considerable weight.
TWO-CYLINDER AUTOMATIC SYSTEMS.
79
When the intercepting valve closes the receiver passage, the boiler
steam from the starting valve reaches the receiver beyond the
intercepting valve by means of the annular space round the piston
valve.
The Dean System. This somewhat complicated system has been
employed for a number of American two-cylinder compound loco-
motives. The main features are shown in fig. 7 1 .
The high-pressure slide valve is open at the top, so that the high-
pressure exhaust steam passes through it and through a port a above
it into the space b which communicates with the receiver. The
passage through a can, however, be closed by the descent of a disc
e .'
FIG. 71. Dean Starting and Intercepting Valves.
valve c when there is no steam arriving from the high-pressure
cylinder, thus closing the passage between the two cylinders, but
as soon as the high-pressure cylinder exhausts, the valve c is lifted to
restore communication.
A reducing valve is provided at d whereby boiler steam can pass
from the high-pressure steam chest at a reduced pressure to the
passage e, but the steam is checked at the end thereof adjacent to
the valve c, except when the valve c is lowered, so that it is only
when the passage a is closed that boiler steam can pass to the low-
pressure cylinder. To the valve c is attached a long sliding sleeve ;
when the valve is lowered, ports /in this sleeve co-operate with ports
at the lower end of the passage e 1 , which constitutes a continuation of
the passage e to allow steam to pass to the space b.
80
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
The Player System. This system is associated with another of
the American locomotive building firms the Brooks Locomotive
Works, which is now embodied in the American Locomotive Company.
In this arrangement (fig. 72) the live steam supply valve a, which
also acts as a reducing valve, is combined in the same casing with the
intercepting valve b. The passages c d e are connected respectively
with the high-pressure exhaust, with the receiver, and with the live
steam supply. When steam is admitted to e, the valve a is forced
to the left, so that steam can pass from e past the small end of the
valve a and through the ports a 1 to its interior, and thence to the
receiver, the movement of the valve a to the left forcing the
intercepting valve b, which movement is assisted by the pressure
of the steam, against its seating, so as to close the passage c connect-
ing with the high-pressure cylinder. As soon as there is exhaust
FIG. 72. Starting and Intercepting Valves Brooks Locomotive Works
Player System.
from the high-pressure cylinder the intercepting valve b is forced
to the right, thereby closing the valve a, and the engine works
compound.
The Rogers Automatic System. This system, introduced by the
Rogers Locomotive Works (U.S.A.), has now been superseded by a
non-automatic system, but the old system is of sufficient importance
for inclusion in this chapter.
The combined starting and reducing valve (fig. 73) is located at
a, and comprises a valve a 1 and a piston a 2 mounted on a stem, live
steam being admitted for starting to the space between them, and the
lower side of the large valve being exposed to any pressure within a
pipe b leading to the intercepting apparatus. When there is no
pressure in the pipe b the live steam pressure admitted between the
valve a 1 and the piston a 2 opens the valve a 1 so that the steam can
pass to the pipe b, but as soon as there is sufficient pressure in the
pipe b the valve a 1 is lifted on to its seating and the live steam
TWO-CYLINDER AUTOMATIC SYSTEMS.
81
supply is cut off. The combined valves a 1 a 2 serve the purpose of a
reducing valve.
The presence of the reduced pressure boiler steam in the pipe b
causes the closing of the intercepting valve c, the steam first passing
through the small passage d to the back of a plunger d l , which is
operated to move a hollow piston valve e to the right, closing the
valve c, and thereby cutting off communication between the high- and
low-pressure cylinders ; at the same time the movement of the piston
e places the ports / and g in communication, so that steam from the
FIG. 73. Rogers Locomotive Works (Automatic) System.
pipe b can enter the hollow of the piston e directly, and escape there^
from through the port h to the receiver. As soon as the high-
pressure cylinder supplies exhaust steam to i the valve c is forced
open, and the piston e and the plunger d l are consequently moved
back, cutting off the supply of steam from the pipe b ; the con-
sequent accumulation of pressure in the pipe b causes the closing
of the starting valve a 1 a 2 , so that the engine then works compound.
Usually this system has been applied so that the starting valve
cannot act except when the reversing gear is placed in full forward
and backward gear, and this result is obtained by means of the
device shown in fig. 74.
6
82
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
The cam plate m is connected by the rod n with the reversing gear,
so that when full, or nearly full, gear is employed, the non-concentric
portions of the cam groove m act to move the reach rod o a short
distance to the right, the rod o being unaffected in intermediate
positions of the cam plate m. The link p holds the roller fitted to
the end of the rod o, and which engages in the cam groove m' in
its working position.
The rod o extends to the smokebox, where it is connected to the
FIG. 74. Detail View Rogers Locomotive Works (Automatic) System.
arm s, secured on the end of a spindle supported within the smoke
box adjacent to the starting valve ; this carries a short arm t, which
engages in the slotted end of the spindle which carries the valves
a 1 a 2 . Unless the rod o is operated, the arm t prevents the movement
of the valves a 1 a 2 for allowing a non-compound start of the engine,
but when full gear is employed and the rod o is operated by the cam-
plate m, the arm t is lifted sufficiently to enable the starting valve
to operate.
CHAPTER VII.
SEMI-AUTOMATIC SYSTEMS (LINDNER TYPE).
CONTENTS : The Lindner System Modifications of the Lindner System The
MafFei System Two-cylinder Swiss System The Cooke Starting Mechanism
Golsdorf System.
THE third division into which two-cylinder systems of compounding
may be classified is that of which the Lindner apparatus may be
considered the prototype. In many respects the arrangements
employed are far simpler than those necessary for even the simplest
apparatus described in Chapters V. and VI., for in most cases inter
cepting valves are dispensed with and the starting valve is little more
than a plain steam admission valve or device. The main character-
istic of the systems of this class is, that non-compound working
results from the placing of the reversing mechanism in nearly full
gear, the apparatus being otherwise automatic as soon as the engine
has been linked up for expansive working.
In several instances, as in the case of the Lindner system, the
desired result is obtained by so simplifying the starting arrangements
that no intercepting valve is required, the only valve provided being
one connected with the reversing gear, whereby boiler steam can be
directly supplied to the low-pressure cylinder. In some cases there
is also provided means connected with the regulator in the steam
dome so that steam can be cut off entirely from this valve, to ensure
that boiler steam cannot pass to the low-pressure cylinder in the
event of the reversing gear being placed in full gear before steam is
admitted by the regulator to the high-pressure cylinder, and to
enable the live steam supply to the low-pressure cylinder to be cut
off by partially closing the regulator, even although full gear is
employed.
The Lindner System. Fig. 75 shows the arrangement first
employed by Herr Lindner ; and although various improvements have
been incorporated in recent years, the system has not been changed
in important particulars.
In the steam pipe casing of the regulator an auxiliary steam pipe
a is fitted, and this is connected with a four-way plug cock b, which
is connected with the reach rod of the reversing gear, so that it is
83
84
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
only in the extreme positions that a through way is provided for the
steam. After passing this valve the steam enters the receiver pipe
c, so that it can operate in the low-pressure cylinder.
The high-pressure slide valve (fig. 76) is formed with small
auxiliary ports so that both ends
of the cylinder are placed in com-
munication with the receiver, and
the high-pressure piston is there-
fore balanced so that when the
low-pressure piston is being oper-
ated, as at starting, with boiler
steam, the back pressure on the
H.P. piston is minimised. As soon
as the engine is "linked up," the
slide valve travel becomes such
that the auxiliary ports do not
operate.
Usually the regulator valve is
so arranged that, when partially
closed, steam is cut off from the
pipe a.
Modifications of the Lindner
System. According to another
arrangement, specially suitable for
goods engines, the steam pipe a
is led, beyond the valve b, to the
side of the high-pressure cylinder,
where it opens into the cylinder
at about half stroke, so that boiler
steam enters on one side or other
of the H.P. piston, according to
its position, and passes thence,
either through one of the auxili-
ary ports of the H.P. slide valve
or through the exhaust, to the re-
ceiver, and so to the low-pressure
cylinder, the high-pressure piston
being balanced as above described.
This arrangement is really only
useful so far as it enables the
low-pressure piston to be operated
when the high-pressure crank is
FIG. 75.-Regulator and Starting Valve on a dead centre, and is not suit-
Lindner System (original Design), able for continued non-compound
working.
According to another arrangement, a small piston valve is con-
nected to the yoke of the low-pressure slide valve so as to move
correspondingly therewith, and this piston valve works in a small
cylinder attached to the steam chest so as to govern ports whereby
SEMI-AUTOMATIC SYSTEMS (LINDNER TYPE).
85
boiler steam is admitted to the low-pressure steam chest when the
slide valve has full travel.
One such arrangement is shown applied to a locomotive in fig. 77,
and a further arrangement, suitable more particularly for passenger
locomotives, is shown in fig. 78. The live steam supply for the low-
pressure cylinder is obtained from the ordinary steam pipe, so that
a special regulator is not required, and the entry of boiler steam to
the low-pressure steam chest is controlled by a valve surface formed
on the back of the low-pressure slide valve.
The Maffei System. This system was first introduced in 1894.
Figs. 79 and 80 show the arrangement em-
ployed at that time for engines supplied by
the firm of J. A. Maffei to the Bavarian State
Railways.
The intercepting valve a is directly con-
nected with the reversing gear through the
intermediation of the peculiar gear shown, the
arrangement being such that when the revers-
ing gear is in either of the extreme positions
the valve a, and, indirectly, the live steam
valve b, are operated so that the engine works
non-compound ; and, as soon as the gear is
linked up somewhat, the valves are so moved
that compound working occurs. As shown,
the valves are in position for non-compound
working.
The intercepting valve a governs the steam
distribution of the high- and low - pressure
cylinders as shown, connecting the high-pres-
sure cylinder with the receiver or with the
blast pipe as may be necessary. The live
steam valve b allows boiler steam to pass to
the receiver, and thence to the low-pressure
cylinder when necessary, the steam being wire-
drawn to reduce its pressure; and this valve
is operated by the engagement of the sleeve c
with the bell crank lever d when the spindle e
is moved, the spring/ returning it to the non-
compound position, as soon as permitted, for the purpose of closing
the valve b. It will be seen that, whether the engine is in forward
or backward gear, the longitudinal movement of the spindle e is very
short, and is the same in either case. Fig. 80 shows the position of
the operating mechanism when working compound.
Two-cylinder Swiss System. A two-cylinder system has been
fitted to a number of Swiss locomotives, having inside cylinders and
fitted with a special starting valve designed by the builders, " The
Swiss Locomotive Works " of Winterthur. This valve provides for
the admission of live steam to the L.P. cylinder when the reversing
lever is in a position giving an admission of more than 70 per cent.
F IG . 76. Slide Valve
and Steam Ports
Lindner System.
86
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
of the stroke, but directly the valve gear is linked up to less than
this the mechanism automatically changes the connections, and the
engine then works compound.
The Cooke Starting Mechanism. This system has in past years
been employed for a number of engines built by the Cooke Locomotive
FIG. 77. Starting Mechanism Lindner System (improved Form).
Works (U.S.A.), though its use has been practically discontinued
since the amalgamation of this firm into the American Locomotive
Company.
For starting, steam is admitted from the steam dome by a pipe
under the control of a cock controlled from the regulator lever or
handle, the arrangement being such that, by a special mechanical
SEMI-AUTOMATIC SYSTEMS (LINDNER TYPE).
87
connection, the cock can only be opened when the regulator is
closed.
Should an engine fitted with this mechanism be unable to start in
the ordinary way owing to the fact that both steam ports of the
high-pressure cylinder are closed, the driver closes the regulator
again and opens the cock by the auxiliary device. Steam can then
pass by the pipe past a reducing valve to the low-pressure steam
chest, so that the low-pressure cylinder starts the engine. Immedi-
FIG. 78. Diagrammatic Arrangement modified Lindner System.
ately this takes place, the driver opens the regulator and the cock
is consequently closed, the engine working thereafter as a compound.
The Gb'lsdorf System. This system shares with the Lindner
system the distinction of being the most frequently employed of
systems of the character under notice, and although of somewhat
later date than the Lindner system, it is probable that the engines
fitted with the Golsdorf starting apparatus are more numerous than
those fitted according to Herr Lindner's methods. In fact, Golsdorf
compound engines, besides being the standards for the Austrian State
Railways, are also to be found on some of the German railways, or
the railways of the Balkan States, and in Hungary, Russia, Sweden,
and in a few cases in the United States and elsewhere.
88
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
SEMI-AUTOMATIC SYSTEMS (LINDNER TYPE).
89
The arrangement employed by Herr von Golsdorf is simplicity ex-
emplified, for it consists merely in providing two small ports a a
(figs. 81 and 82), formed through bridges placed across the steam
FIG. 80. Detail of Mechanism MafFei System.
admission ports of the low-pressure cylinder, to which auxiliary ports
live steam is supplied, the slide valve having ribs working over these
bridges, the arrangement being such that it is only when the slide
valve has maximum travel, owing to the reversing gear being in full
forward or backward gear, that the auxiliary ports are uncovered.
FIG. 81. Slide Valve and Auxiliary Steam Ports Golsdorf System.
By this means, by placing the reversing mechanism in full gear,
boiler steam can enter the low-pressure cylinder although there is
no high-pressure exhaust steam available, thus enabling the engine
to start in any position. If at any other time full gear is employed,
90
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
the live steam admission necessarily takes place also, but this only
occurs exceptionally, and in some cases a small valve is fitted, whereby,
after the engine is started, the driver can cut off the supply of steam
FIG. 82. Slide Valve and Auxiliary Steam Ports (Cross Section)
Golsdorf System.
to the auxiliary ports. As soon as the reversing gear is linked up,
the slide valve travel becomes such that the auxiliary ports are never
uncovered.
In some cases the auxiliary ports are placed to one side of the
FIG. 83. General Arrangement Golsdorf System.
steam chest, and the slide valve has a small side extension for con-
trolling them.
Fig. 83 shows in diagrammatic plan the general arrangement
employed.
Since about the year 1900 the system has also been applied to
four-cylinder compound locomotives in which all four cylinders drive
the same axle, the cranks being 90 apart round the circle of revolution.
CHAPTER VIII.
THREE-CYLINDER COMPOUND SYSTEMS.
CONTENTS : General Remarks Methods of Compounding with Three Cylinders
Webb Three-cylinder System for Passenger and Tank Engines The
Webb System as applied to Goods Engines The Riekie Three-cylinder
System The Sauvage System The Swiss System The Smith System.
General Remarks. In its simplest form three-cylinder compound
systems for locomotives must be considered as being directly derived
from two-cylinder systems by the division of the large low-pressure
cylinder into two low-pressure cylinders of about the same diameter
(or less) as the high-pressure cylinder.
Methods of Compounding with three Cylinders. Thus, the
proposition of Monsieur Jules Morandiere in 1866 referred to in
Chapter IV. supposes the use of three cylinders, all of about the same
size, one of them using boiler steam, while the other two divide the
exhaust steam from the high-pressure cylinder between them, their
compound volumes being together equal to one large cylinder, as
would be employed for a two-cylinder system.
In other propositions it was suggested that three cylinders should
be employed in a manner which approximates even closer to the
two-cylinder engine, and a general arrangement of this kind which
was proposed by Monsieur Mallet in 1879, and patented in this
country by Mr Lapage in 1889, is shown in fig. 35.
In true three-cylinder systems it is intended that some mechanical
advantage shall be obtained as well as direct economy through
compounding, and therefore in all practical systems each of the
cylinders has complete driving gear, there being three cranks,
disposed in one way or another; as a rule, too, arrangements are
provided to enable increased power to be exerted when necessary.
During the whole history of locomotive compounding it is believed
that only five three-cylinder systems have been actually employed
in practice, and these naturally divide into two divisions, (a) having
one high-pressure cylinder and two low-pressure cylinders, and (b)
having two high-pressure cylinders and one low-pressure cylinder.
The first of these divisions is a direct development of the ordinary
two-cylinder compound locomotive, with the added advantage that
91
92 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
three driving cranks can be arranged for, as well as other advantages
obtained.
In the other division the systems comprise an ordinary two-
cylinder high-pressure engine, and the steam, after use in these
cylinders, is re-used to obtain further work before the steam is
exhausted up the chimney. Two systems only come within this
division, and only one of them (the Riekie system) strictly conforms
to this statement, the sole object of the low-pressure cylinder being
to enable work to be utilised which in a two-cylinder high-pressure
engine would be wasted ; whereas the other (the Webb system) only
partially satisfies this statement, for it also includes the important
feature of compounding, that the expansion of steam from boiler pres-
sure to final exhaust is carried out in two more or less equal stages.
It will be most convenient to deal with the second of our divisions
first.
The Webb Three-cylinder System for Express and Tank Engines.
Reference to figs. 5 and 31 will indicate the main features which
characterised these engines.
As will be seen, the two high-pressure cylinders are set back on
the frames and drive the rear pair of driving wheels, while the large
low-pressure cylinder is placed between the frames under the smoke-
box so as to actuate the other driving axle. As no coupling rods
are fitted, it is possible for the two pairs of wheels to rotate
independently, and after starting it generally requires a few
revolutions to enable the two sets of mechanism to " get into step."
Occasionally this renders a start somewhat jerky, and in the case
of the tank engines this provided a primary reason for their removal
from London local traffic, which entailed stopping and starting every
half-mile or so.
As already stated, no special provision is made for starting, so
that all the work for the first one or two strokes has to be done in
the high-pressure cylinders, but this fact, although occasionally
causing trouble with very heavy loads, has not proved so serious as
it may appear to be. A device has, however, been fitted whereby,
before starting, boiler steam can be admitted to the low-pressure
cylinder on both sides of the piston for warming up the cylinder
walls before the working steam enters.
In Mr Webb's patent of 1881 means were described whereby
boiler steam could be admitted to the low-pressure cylinder and the
high-pressure exhaust diverted to the chimney, but it is not believed
that such devices were ever fitted, unless experimentally to the first
engine.
At starting, if slipping occurs, there may be an accumulation of
exhaust steam from the high-pressure cylinders before it can be used
in the low-pressure cylinder, and to accommodate this, fairly large
receiver space is provided by means of pipes extending from the
high-pressure cylinders into the smokebox, round the inside of which
the pipes are curved, one from either side, so that the steam is
reheated somewhat before use in the low-pressure cylinder.
THREE-CYLINDER COMPOUND SYSTEMS. 93
In some classes of three-cylinder compound engines of Mr Webb's
design, means were provided whereby the cut-off ratios of the
respective cylinders could be relatively varied, firstly by fitting two
reversing levers in the engine cab (this arrangement was discarded
after a time), and secondly by means of a special wheel and screw
gear by which the reversing rods of the high-pressure and low-
pressure valve gears could be worked together or independently
adjusted. In later engines, however, the necessity for this was
obviated by arranging the low-pressure valve to work with an
invariable cut-off ratio, the driver being concerned only with the
reversing gear of the high-pressure cylinders. This was effected by
employing a single eccentric gear for the low-pressure slide valve,
which, as the engine started moving, automatically took up a position
for forward or backward working according to the direction of
motion initiated by the high-pressure cylinders.
Several other special features were patented by Mr Webb from
time to time, but the main features were unaffected, and in very few
instances were special devices introduced into practice.
Fig. 31 represents the first three-cylinder engine, "Experiment,"
which started work in 1882. In the next two years twenty-nine more
of the same class were introduced. These engines had 6 ft. 9 in.
driving wheels, 150 Ibs. steam pressure, high-pressure cylinders
13 in. diameter (the first engine had cylinders only 11 J in. diameter
when built), low-pressure cylinder 26 in. diameter, and a stroke of
24 in.
Following these came a series of forty engines having considerably
greater power, the new class being generally referred to as the
"Dreadnought" class. They had bigger boilers, 175 Ibs. pressure,
14-in. and 30-in. cylinders, and 6 ft. 3 in. wheels.
All of the engines of these two classes have been scrapped during
1905-6.
In 1889 and 1890 ten larger engines were built, known as the
"Teutonic" class; and, somewhat curiously, these engines, though
differing only in dimensions and minor particulars from their pre-
decessors and their successors, have always had a most exemplary
character, though it is difficult to say why this should be so.
Whereas the earlier engines wers somewhat erratic and undependable
at times, the " Teutonic " class have always enjoyed a good reputation
for satisfactoriness and for uniformly good work. These engines
have 14-in. and 30-in. cylinders, and 7-ft. driving wheels. Some of
these engines have recently been scrapped.
In the years 1891-4 ten large eight-wheeled engines were built.
These engines, known as the " Greater Britain " class, had very long
boilers, but, as regards their compound features, corresponded generally
with the class previously described, except that the high-pressure
cylinders were 15 in. diameter, and that the single-eccentric gear
above referred to was fitted to them.
The final series of three-cylinder compound express engines built
in 1894-8 consists of ten engines, referred to generally as the "John
94 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
Hick " class, corresponding to the " Greater Britain " class, but in-
tended for use between Crewe and Carlisle, where severe gradients
occur, and therefore having driving wheels only 6 ft. 3 in. diameter.
During the years 1884-7 four tank engines were converted or built
as three-cylinder compound engines, but these were not multiplied,
and the writer has Mr Webb's own authority for stating that they
were never considered as other than experimental engines, which
experiments were not sufficiently satisfactory to warrant further
work on the same lines.
Webb System as applied to Goods Engines. Mr Webb's three-
cylinder compound system has also been applied to upwards of a
hundred eight-coupled mineral engines, dated between the years 1893
and 1899. These engines necessarily do not include the use of non-
coupled driving wheels, and all three cylinders drive the same axle,
the second from the front. These powerful engines have always done
very good work, but Mr Whale, the present Locomotive Chief, is now
converting them to two-cylinder non-compound engines with larger
boilers as they go into the shops for heavy repairs and rebuilding.
During the years 1883-1890 about seventeen Webb compound
engines were built for service in France, South America, India, and
the United States (Pennsylvania Railroad), and although in no case
were other engines built, the reports of their work were fairly satis-
factory.
The Riekie Three-cylinder System. This system shares with
that just described the peculiarity of employing two high-pressure
cylinders and only one low-pressure cylinder, but in other respects
it comprises several features which differentiate it from Mr Webb's
system.
In introducing this system, Mr Riekie, who in 1894 converted one
of the Webb compound engines belonging to the North-Western
Railway of India according thereto, had for his object to employ the
high-pressure cylinders as nearly as possible in the same manner as
they are employed in an ordinary non-compound engine, cutting off
at an early point in the stroke in the usual manner for engines
which are not compound, except when the stress of work requires a
late cut-off, the purpose of the low-pressure cylinder being to enable
further work to be obtained from the steam before it passes up the
chimney. Coupled with this feature is the employment of three
driving cranks 120 apart, whereby an even and regular turning
moment is obtained. As the high-pressure cylinders are designed
to operate as the cylinders of an ordinary engine, they are made of
a size equal to, or only slightly less than, those which would be
employed were no other cylinders fitted, instead of being smaller and
the valve gear adapted for a late cut-off, as usual in all other com-
pound locomotives. It therefore follows that the low-pressure
cylinder is additional, and, owing to the relative crank angles, it is
designed to receive the exhaust steam from one high-pressure
cylinder for one-third of a stroke, and from the other high-pressure
cylinder for the next third of the stroke, the remaining third con-
THREE-CYLINDER COMPOUND SYSTEMS. 95
stituting the expansion portion of the stroke. In practice, Mr
Riekie is able to cut off in the high-pressure cylinders at 25 per cent,
of the stroke or less ; and under ordinary circumstances steam can
be expanded down from 180 Ibs. to 20 Ibs. per square inch, or, under
special circumstances, to as low as 5 Ibs. per square inch.
In one of his patents Mr Riekie provided an arrangement whereby
at starting the reversing gear of the high-pressure cylinders can be
arranged for an 80 per cent, cut-off, but immediately the engine is
in motion the gear is automatically changed to a 40 per cent, cut-off,
after which it can be linked up as desired by the driver for proper
compound working. Other than this device (if employed), no special
starting valve or apparatus is required to enable the engine to start
a heavy train.
It was mentioned in Chapter IV., in the course of our historical
survey, that several suggestions were made in the early days of
locomotive compounding for the employment of three cylinders, one
high-pressure and two low-pressure cylinders, but only three systems
of this class require more detailed consideration in this chapter, and
of these only two may be considered as really belonging to modern
practice, though the other system is also included for completeness.
The Sauvage System. An engine of the "Mogul" (2-6-0) type
was built in 1886 for the Northern Railway of France, to designs
prepared by Monsieur A. Sauvage.
The low-pressure cylinders are placed outside the frames and
drive on to cranks at right angles, and the high-pressure cylinder
actuated a crank on the same axle, which crank bisected the obtuse
angle between the low-pressure cranks.
The valve arrangements employed for this engine are very peculiar
and unusual, but as nothing further has been done with this system,
it is hardly necessary to describe them specially, though the original
engine is still at work.
The Swiss System. This system is associated almost exclusively
with the Swiss Engine Works of Winterthur, Switzerland, though
a considerable number of locomotives have been fitted according to
it, principally for use on Swiss railways.
The two low-pressure cylinders are arranged outside the frames,
the single high-pressure cylinder being placed inside, and in most
cases two separate coupled axles are driven.
A double piston valve controls the passage of steam from the
high-pressure cylinder to the blast pipe or to the receiver. A small
pipe supplies boiler steam to the steam chests of the low-pressure
cylinders, and steam is admitted to them by means of a small
regulator valve.
By suitably operating the double piston valves and the small
regulator, the driver can operate the engine (1) as a compound, (2)
with three high-pressure cylinders exhausting to the blast pipe, (3)
with the low-pressure cylinders only working with boiler steam, and
(4) with the high-pressure cylinder only.
The first engine fitted according to this system was built in 1894
96 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
for use on the St Gothard Railway, for trial against a four-cylinder
engine fitted with very nearly the same valve arrangements. The
four-cylinder design was considered preferable, but for several years
three-cylinder engines of the same kind were supplied to other Swiss
railways, though now four-cylinder engines, compounded according
to the de Glehn system, are principally introduced in supersession of
the older system. Means are also provided whereby the high- and
low-pressure valve gears can be independently adjusted.
The Smith System. This system is one of the few introduced
during the last few years which comprise features which render it
correct to describe the peculiar valve arrangements employed as
pertaining to a system, whereas most other recently introduced so-
called systems are really developments of older systems, or are only
differentiated one from another by the construction of starting
mechanism or by features of design.
The arrangement of cylinders employed by Mr Smith is the same
as that used in the last-described engines, viz. with one H.P.
cylinder and two L.P. cylinders. In most cases all three cylinders
drive one axle with the L.P. cranks 90 apart and the H.P. crank
dividing the obtuse angle; but two engines have just been placed
in service wherein the H.P. cylinder drives one axle and the L.P.
cylinders drive another, the two axles being coupled.
The first engine fitted according to this system was a four-coupled
bogie engine of the North-Eastern Railway, originally a Worsdell
two-cylinder compound engine, which was adapted in 1899 by
Mr Wilson Worsdell, according to Mr Smith's arrangement. The
system has never been applied to other North-Eastern engines,
though it is understood that the record of No. 1619 has been a good
one; but two new four-cylinder compound locomotives of a very
powerful type have just been constructed (see frontispiece) which
embody a four-cylinder development of Mr Smith's system.
In 1901 two four-coupled bogie engines for the Midland Railway
were built by Mr S. W. Johnson immediately before his retirement
from the position of locomotive superintendent, and the record of
these two engines, and of three others built in 1904 by Mr R. M.
Deeley, has been so satisfactory that a number of other engines,
having somewhat larger dimensions, have just been placed in service
on this line.
The two engines referred to above, wherein two axles are employed
for driving, are large Atlantic type engines for the Great Central
Railway, designed by Mr J. G. Robinson, the Locomotive Super-
intendent.
The main object of Mr Smith's system is not so much to obtain
direct economy by compounding pure and simple, but rather, while
obtaining some advantage in this way, to produce an engine which
can be adapted in a very considerable degree to the work required
of it, so that it can work trains single-handed, which, owing to
difficulties occurring on one section only of a journey, would other-
wise require an assisting engine, and it can at other times deal with
THREE-CYLINDER COMPOUND SYSTEMS. 9?
its train in a way which would be difficult or well-nigh impossible
for a non-compound engine of corresponding or greater power.
On the Midland Railway the record of the compound engines is
very notable, and they are great favourites among both the engine-
men and the higher officials of the line.
The starting arrangements introduced by Mr Smith comprise a
duplex valve, one part of which is of an automatic character, whereby
an engine, after starting non-compound, is automatically "changed to
compound as soon as there is sufficient pressure in the receiver from
the exhaust of the high-pressure cylinder for operation in the low-
pressure cylinder, this automatic valve automatically reintroducing
non-compound working should the receiver pressure fall below the
required (but variable) pressure for non-compound working; the
second portion of the mechanism comprises a reducing steam
admission valve, which can be regulated by the driver to admit
boiler steam at any desired pressure to the receiver, so as to cause
the automatic valve to reintroduce non-compound working, and to
supply steam at a pressure suitable for variable requirements to the
low-pressure cylinders, or to reinforce the receiver steam with live
steam to assist work in the low-pressure cylinders.
By this means the mechanism allows of working as follows :
(a) Three-cylinder non-compound, for starting with three large
cylinders (in engines built the H.P. cylinder is 19 in. diameter,
and the L.P. cylinders 21 in. diameter).
(b) Three-cylinder compound.
(c) As compound, the low-pressure steam being reinforced in a
variable degree with live steam.
(d) As a two-cylinder non-compound engine with large cylinders,
larger than could be well supplied with steam did the engine always
have to work in this way.
The last-mentioned method of working results when the steam-
reducing valve is adjusted so that full or nearly full pressure steam is
admitted to the receiver, in which case the high-pressure piston is
nearly balanced, and therefore floats, while the two L.P. pistons (21 in.
diameter) work with steam at full or nearly full boiler pressure.
It will readily be seen that, with such facilities for adapting an
engine to its work, a driver operating his engine intelligently can
obtain very great power or adjusted power according to load of
train and gradient, thus enabling the engine to maintain speed
under circumstances when the speed would fall considerably in the
case of an ordinary engine. The engines can accelerate quickly, and
on a very steep gradient or under exceptional difficulties can work
temporarily as a very powerful non-compound engine, whereby the
difficulty can be surmounted before the large consumption of
steam required for the time being has seriously strained the steaming
capacity of the boiler.
Strictly speaking, economy as ordinarily understood when com-
pound locomotives are in question, is not sought for, though for
the major portion of any journey such an engine effects economy
7
98
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
in a greater or less degree by working compound, but the real
economy arises from the fact that almost any difficulty within reason
can be surmounted by working as a semi-compound or as a simple
engine, and economy of engine power can therefore be effected as men-
tioned above. In some cases means are provided whereby the adjust-
able valve cannot be adapted for the full boiler pressure of steam.
At starting, it may occur that the high-pressure slide valve closes
both of the steam ports, and under these circumstances the reduced
boiler steam admitted to the receiver would enter one end of the
cylinder through the exhaust port and tend to reverse the engine ;
this is prevented by fitting a
non-return valve in a passage
connecting the two ends of the
high-pressure cylinder and the
receiver, so that receiver steam is
admitted to both ends of the H.P.
cylinder, the piston of which is
therefore balanced. Under these
circumstances, the low-pressure
cylinders start the train until
the high-pressure slide valve has
moved sufficiently to open one or
other of the steam ports to steam,
when the non-return valves auto-
matically close.
Figs. 84 and 85 show the ar-
rangement of parts and the con-
struction of duplex valve gener-
ally employed in carrying the
Smith system into practice.
Fig. 86 is a general view show-
ing the smokebox and cylinder
arrangements, a is the high-
pressure cylinder, the steam dis-
tribution of which is controlled
FIG. 84. Starting Valve Smith
Three-cylinder System.
by piston valves at a 1 (these valves are of Mr Smith's special design,
but do not concern us here) ; b b are the low-pressure cylinders,
whose steam distribution is controlled by ordinary slide valves work-
ing over vertical port faces ; c is the receiver space ; d the casing
of one of the non-return valves connecting the receiver space with
the respective ends of the high-pressure cylinder ; e e the exhaust
passages from the low-pressure cylinders ; / the casing of the duplex
valve ; g the boiler steam supply pipe to / ; and h the pipe connecting
the duplex valve with the receiver.
The large spindle i carries a valve i l which opens or closes the
opening k, whereby communication is opened or closed between the
pipes g and h ; and the two ends of this spindle work steam-tight in
the casing as shown, a spring I being fitted to assist the closing
movement, and to give the valve the character of a reducing valve.
THREE-CYLINDER COMPOUND SYSTEMS.
99
The passage m communicates with the live steam supply pipe g, so
that boiler steam presses upon the spring loaded valve n. The
spindle o has a screwed portion o l engaging in screw threads formed
in the casing, whereby, when the spindle o is rotated through the
rod p, which extends into the driver's cab, where a wheel or handle
is fitted for rotating it, the spindle is moved longitudinally, and the
collar s compresses the spring t, more or less, so as to adjust the
pressure at which the valve n will open. After passing the valve n,
steam leaks through the small opening v to the space above the end
of the spindle i.
At starting, there being no pressure in the receiver, the valve i
lifts and allows steam to pass from the pipe g to the pipe li for use
FIG. 85. Pressure -Regulating Valve Smith Three-cylinder System.
in the low-pressure cylinders, and the engine starts as a two- or three
cylinder non-compound. As soon as there is sufficient receiver
pressure the valve i 1 automatically closes, and the live steam supply
is cut off, the engine then working compound.
If at any time the pressure in the receiver falls below that
required for low-pressure working, the valve i 1 opens to admit boiler
steam from g to h, but the pressure at which this will occur is
adjusted by the driver operating the rod p so that the spring t is
more or less compressed, and at the desired pressure, or a proportion-
ate pressure, boiler steam enters by the valve ?, leaks through the hole A:
to the space above the end of the spindle i, and presses the valve i 1
upon its seat with such force that the boiler steam has to overcome
this pressure as well as that in the receiver before it can pass to h.
Thus, for ordinary compound working, the pressure above the
spindle i is such that the valve i 1 lifts immediately the pressure in
100
LOCOMOTIVE COMPOUNDING
SUPEKHEATIKG.
the receiver falls below, say, 80 Ibs. per square inch, admitting boiler
steam at the requisite reduced pressure. If additional power is
required in the low-pressure cylinders, the valve n is adjusted so that
the closing pressure on the valve i l is increased, and it therefore
results that boiler steam will be admitted to the receiver immedi-
FIG. 86. General Arrangement Smith Three-cylinder System.
ately the pressure falls below, say, 120 Ibs. per square inch, the result
being that the receiver receives both H.P. exhaust and reduced
boiler steam for reinforced or semi-compound working.
Several other constructional features, such as cushioning and
leakage-preventing means, are also employed, but these need not be
dealt with here.
CHAPTER IX.
FOUR-CYLINDER TWO CRANK SYSTEMS (TANDEM CLASS).
CONTENTS: General Remarks The Du Bousquet " Woolf " System The
Brooks System The Vauclain Tandem System The American Locomotive
Company's System The Sondermann System Mallet Tandem System in
Russia Tandem Compounds for Hungarian State Railways The new Du
Bousquet Tandem System.
General Remarks. The tandem system of compounding is prob-
ably the simplest method of adapting compounding to the loco-
motive engine, for it admits of the adaptation of an ordinary two-
cylinder non-compound engine for compound working by the mere
addition of two small cylinders for high-pressure steam, the original
cylinders serving as low-pressure cylinders ; beyond this there is
very little complication, and very few additional parts are required.
In fact, in the case of some experimental engines the foregoing
statement represents what has actually been done.
In practice, however, it is of course preferable to properly design
the cylinders and mechanism, but beyond the fact that two additional
cylinders are required, each having a piston and a piston rod (an
extension of the ordinary piston rod in most cases), and fitted with
slide or steam controlling valves, and that a few connecting pipes
may be necessary, the engine is no more complicated than an ordinary
non-compound engine. Owing to the fact that the cylinders are
similar on either side of the longitudinal centre-line of the engine,
starting arrangements, such as are necessary with a compound engine
having two unequal cylinders, may be very considerably simplified,
or may be dispensed with altogether.
Remarks of a corresponding nature also apply to a great extent in
the case of other four cylinder two-crank systems, as described in the
next chapter.
Tandem compound engines may be divided into two main divisions :
(1) those wherein the two cylinders of each tandem pair are formed
together in one casting or very closely connected, this section being
farther capable of classification according to whether one slide valve
or two is or are employed at each side of the engine, and according
to whether the steam passes direct from one cylinder to the other
101
102
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
without the intermediation of a "receiver" (referred to as the
" Woolf " method), or whether a " receiver " is employed ; and (2)
those wherein the cylinders are separated and distinct, though both
pistons at either side are mounted on the same piston rod or con-
nected to the same crosshead, and the two slide valves (each cylinder
necessarily has its own slide valve in this case) are mounted on the
same valve rod, or the respective valve rods are connected to work
together.
In Chapter IV. some early attempts at tandem compounding for
locomotives have been mentioned and others referred to, and now
the most important of the systems which have been actually employed
FIG. 87. Du Bousquet (Woolf) Tandem System.
will be referred to in detail, systems of the first class above referred
to first receiving attention.
The Du Bousquet "Woolf" System. To Monsieur G. du
Bousquet, Chief Locomotive Engineer of the Northern Railway of
France, must be credited the first notable introduction of tandem
compound locomotives into service ; and, rather curiously, he is also
responsible for the latest successful introduction of such engines,
though on a different system.
In 1882 this well-known engineer converted three eight-coupled
outside cylinder goods engines by fitting at each side a high-pressure
and a low-pressure cylinder end to end. In 1890 extended trials
with these engines having proved very satisfactory, twenty new
engines of the same class were built, and it is believed that all of
these twenty-three engines are still at work, though superseded to
some extent by new engines of other classes.
Fig. 87 is a section of a pair of cylinders for one of these engines.
FOUR-CYLINDER TWO-CRANK SYSTEMS (TANDEM CLASS). 103
As will be seen, the two cylinders are cast together, and the low-
pressure cylinder has two piston rods which pass outside the high-
pressure cylinder, all three rods being connected to the same
crosshead. A single slide valve of special construction controls the
steam distribution of both cylinders, the arrangement of ports and
the path of the steam for one position of the pistons being indicated.
To all intents and purposes, the slide valve consists of two slide
valves, one inside the other, and rigidly connected therewith.
FIG. 88. Starting Mechanism Du Bousquet (Woolf) Tandem System.
An important feature of this arrangement is that the cylinders are
placed as close together as it is possible for them to be, and that no
stuffing boxes are required between them, thus obviating one of the
great disadvantages of many tandem systems, i.e. the difficulty of
obtaining access to stuffing boxes between the cylinders of each
pair.
To facilitate starting, the valves shown in fig. 88 are fitted.
The passage a communicates with the passage b (fig. 87) formed
through the valve chest cover, and through the opening in the top of
the duplex slide valve, with the internal passages of the slide valve,
104
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
and so to the ports of the low-pressure cylinder. The spring valve
c governs the passage of boiler steam at a reduced pressure to the
passage a, and closes automatically as soon as the high-pressure
cylinder supplies exhaust steam of a sufficient pressure. The valve
d allows air to enter the cylinders when the engine is running with
steam shut off. The valve e is a special type of steam regulator, and
it is provided with a small port, as shown, whereby, when steam is
allowed to pass to the cylinders, a small supply passes to the cylinder
/ and presses on the small piston g, thereby ensuring the closing of
the air valve d.
The Brooks System. A tandem compound engine was built in
1892 by the Brooks Locomotive Works for the Great Northern
Railway (U.S.A.), and this engine, of the Consolidation (2-8-0) type,
FIG. 89. Section of Cylinders and Slide Valves Brooks Locomotive
Works (Player) System.
has been followed by several other tandem engines, though such
engines (or any tandem compound engines) have never become very
common in American practice, notwithstanding that many of them
are notable machines. Fig. 89 shows the construction and arrange-
ment of cylinders, slide valves, and other parts.
As can be seen, the two cylinders of each pair are closely con-
nected, but the two slide valves are moved oppositely to one another
through a rocking lever located in the receiver, the H.P. slide valve
being of hollow piston design, while the L.P. slide valve is of
ordinary D-construction. The bearing of the rocker arm, which is
of course inaccessible during work, is oiled through a hole bored
through the centre of the spindle.
A reducing starting valve, which operates only when the reversing
gear is placed in full forward gear, to admit boiler steam at a
reduced pressure to each low-pressure cylinder, is shown in fig. 90.
The operating rod a, which is connected with the reversing lever, has
FOUR-CYLINDER TWO- CRANK SYSTEMS (TANDEM CLASS). 105
an inclined face formed upon it at a 1 , whereby, when the lever is
moved fully over in forward gear, the reducing valve is opened to
allow steam to pass to the low-pressure cylinders.
The Vauclain Tandem System. This system has been employed
for a number of American compound engines in recent years (some
of them among the largest and most remarkable engines in the
world) ; and as it also comprises the close juxtaposition of a high-
and a low-pressure cylinder, and the use of a single slide valve (or
rather two valves working in one steam chest) for two cylinders, it
requires consideration at this stage, though other tandem compound
systems antedate its use by several years.
Fig. 91 is a section of a pair of cylinders and valves according to
this system.
Each cylinder, with its valve chest, is cast separately, and is
separate from the saddle. The steam connections are made by a
FIG. 90. Starting Mechanism Brooks Locomotive Works (Player)
Tandem System.
pipe from the saddle to the high-pressure valve chest, and the final
exhaust takes place through an adjustable connection between the
low-pressure cylinder and the saddle casting. The valve, which
is double and hollow, admits steam to the high-pressure cylinder,
and at the same time distributes the high-pressure exhaust from
the front end of the high-pressure cylinder to the back end of the
low-pressure cylinder, or vice versa, as the case may be, without
the necessity of crossed ports. As shown, A is the high-pressure
valve by which steam is conducted from the live steam openings
through external cavities B and B to the high-pressure cylinder.
The exhaust from the high-pressure cylinder passes through the
opening C to the steam chest, which acts as a receiver ; D is the
low-pressure valve connected to the high-pressure valve by valve rod
E. This valve in its operation is similar to the ordinary slide valve.
The outside edges control the admission, and the exhaust takes place
106
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
through the external cavity F. The starting valve connects the
live steam ports of the high-pressure cylinder.
The system has been employed for a large class of ten-coupled
(2-10-2 type) engines recently supplied to the Atchison, Topeka,
and Santa Fe Railroad (United States). The cylinder diameters are
19 in. and 32 in., with a stroke of 32 in. The engines weigh in
working order (without tender) 129 English tons.
The American Locomotive Company's System. This company
has also been responsible for the introduction of tandem compound
engines in the United States ; and such engines have been built
at various times in connection with the various firms which are now
amalgamated into the American Locomotive Company. Fig. 92
STARTING VALVE
FIG. 91. Section of Cylinders for Vauclain Tandem Compound Engine.
is a section of cylinders as now employed for engines of this class.
In several cases the engines correspond very closely with those built
by the Baldwin Works ; and on the Atchison, Topeka, and Santa Fe
Railroad there are " decapod " (2-10-0) engines built by both firms,
these engines being the immediate predecessors of the engines just
described, and being but little smaller.
The hollow piston valves are mounted on the same valve rod in a
common steam chest, that for the H.P. cylinder being arranged for
internal admission, and that for the L.P. cylinder for external
admission. The design is such that steam can be admitted to the
same side of each piston by means of the crossed ports of the high-
pressure cylinder. As shown, steam is being admitted to the left of
each piston.
Fig. 93 shows the starting valve employed. This valve is secured
FOUR-CYLINDER TWO-CRANK SYSTEMS (TANDEM CLASS). 107
to the side of the steam chest over the high-pressure cylinder, and
connects directly with the steam passages of that cylinder. A by-
pass valve for the high-pressure cylinder is also contained in the
casing of the starting valve. The low-pressure cylinder is also
provided with a by-pass valve for relieving excessive steam pres-
sure, or for freeing from back pressure when running with steam
shut off.
108
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
rrfn
FOUR-CYLINDER TWO-CRANK SYSTEMS (TANDEM CLASS). 109
At starting, the starting valve is placed by the driver in the
position shown by means of a lever in the cab, and steam then passes
to the H.P. steam chest through a short steam pipe, and thence
through the ports D and H, which register with the H.P. steam
ports in the steam chest. From D the steam passes by the ports
E and G and thence by the by-pass valves B B to the port H, the
valves BB being held up to their seats by pressure from below
through the port C, which opens directly into the steam chest. The
steam thus has access to both H.P. steam ports, and passes through
both piston valves to the low-pressure cylinder, which thus works
with high-pressure steam.
For working compound, the starting valve A is moved so that it
closes the port E, shutting off high-pressure steam from the low-
pressure end of the steam chest.
A difficulty attending the use of tandem compound locomotives is,
that the packing of the piston rod between the high- and low-pressure
cylinders is so located that it cannot be seen, and it is difficult to
ascertain whether it leaks or is tight. Another difficulty is, that it is
extremely hard to get at the low-pressure cylinder packing, and it
sometimes takes several hours to make a complete inspection of this
packing.
It is such difficulties as these which militate against the general
introduction of tandem compounding for locomotives, but in a large
measure these are overcome or considerably reduced in recent
practice.
Sondermann System. Some years ago (about 1894-5) four
engines were equipped by the firm of Krauss & Co. of Munich with
Sondermann's tandem cylinders, but the engines were afterwards
converted to ordinary design, as they did not show any noticeable
advantage.
Fig. 94 is a section of the cylinders then employed, from which it
will be seen that a peculiar construction was employed. The two
pistons were connected, and at one side worked over a boss formed on
the cylinder cover, in which one of the high-pressure steam ports was
formed. One slide valve controlled the steam distribution of the two
cylinders, being formed to work over five ports instead of three.
A few systems which have been employed to some extent, wherein
each cylinder is complete in itself, will now be considered.
Mallet Tandem Compound Engines. Although Monsieur Mallet
published designs for a tandem system of compounding in 1879, it
was not until 1891 that any engines were built, but in that year a
passenger engine was built at the Alsatian Works for the South-
western Railway of Russia, to the designs of Messrs Mallet, de
Glehn, and Borodine.
Fig. 95 is a section through the cylinders showing the valve
arrangement.
In this case the high- and low-pressure cylinders are cast separately,
the low-pressure cylinder being nearest to the driving wheels. The
arrangements for operating the two slide valves together, and the
110
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
general features of cylinder construction and arrangement, are shown
in the figure.
To facilitate starting, a modification of the Mallet starting valve,
as introduced for two-cylinder compound engines, is employed, where-
by steam is admitted to the low-pressure cylinders whenever the
reversing gear is placed in full forward or backward gear.
FIG. 94. Section of Cylinders Sondermann System.
Since the introduction of this engine, tandem compound locomotives
have been introduced in considerable numbers for the Russian rail-
ways, the engines being of various classes, and in some cases being
of notable dimensions.
Tandem Compound Engines for Hungarian State Railways. It is
somewhat strange that Hungary and Russia should be the only
nr > >2^*rV==!=. ^-^~'C^3 i i^vvv^T- r 5 r v^C^rj
FIG. 95. Section of Cylinders Mallet Tandem System.
countries where tandem compound engines have been seriously em-
ployed for express service. In both cases each of the cylinders is
complete in itself, having its own steam chest and slide valve, the two
valves being operated from the same valve rod at each side of the
engine.
Fig. 96 is a sectional view showing the arrangement and con-
struction of cylinders and valves employed for the Hungarian State
FOUR-CYLINDER TWO-CRANK SYSTEMS (TANDEM CLASS). Ill
Railways in 1891, the engines being of the four-coupled bogie
type.
In these engines both of the high-pressure cylinders exhaust into
the same receiver from which both of the low-pressure cylinders are
supplied. At starting, live steam is admitted to the receiver for use
in the low-pressure cylinders by means of a starting valve which is
opened by the reversing gear when in full gear forward or backward.
This starting valve is the same as that described in Chapter V. in
reference to Hungarian two-cylinder compound locomotives. The
two-cylinders of each pair are cast together, though each is largely
independent as regards access to stuffing boxes, etc.
The new Du Bousquet Tandem System. In 1901 Monsieur du
Bousquet introduced upon the Northern Railway of France a series
of fifteen tandem compound tank engines for working Northern
traffic over the " Ceinture " Railway, a joint railway connecting the
FIG. 96. Section of Tandem Cylinders Hungarian State Railways.
various termini in Paris, and used largely for the interchange of
traffic.
The design differs radically from that of the engines described
earlier in this chapter, the low-pressure cylinders being placed in front,
and being entirely separated from the high-pressure cylinders, and the
piston and valve rods for each cylinder being separate, and connected
by coupling sleeves.
Fig. 97 is a schematic view showing the starting valves and
mechanism.
For actuating the mechanism for changing from non-compound to
compound working compressed air is employed, controlled by the
small valve a operated in conjunction with the regulator ; this valve
allows air to pass by one or other of the pipes b c to the top or the
bottom end respectively of the cylinder d so as to raise or lower its
piston, and thereby to rotate through the mechanism shown the
rotary valve e, which in one position (non-compound) opens communi-
cation between the pipe /, connected with the steam supply pipe g,
for the high-pressure cylinder, and the low-pressure steam chest,
112 LOCOMOTIVE COMPOUNDING AND SUPERHEATING,
another part of this valve at the same time closing communication
between the H.P. and L.P. cylinders through the pipe h. As repre-
sented, the parts are in the compound position. This valve also
FOUR-CYLINDER TWO-CRANK SYSTEMS (TANDEM CLASS). 113
controls communication between the pipe h and a pipe connecting
with the blast pipe through i, so that when cut off from the L.P.
steam chest the H.P. exhaust can pass away.
At the upper part of the figure is shown the rotary valve e e for the
cylinders at the other side of the engine. Both these valves are
operated by the movement of the piston of the one air cylinder d.
A relief valve is fitted at Jc to regulate the pressure in the pipe i.
Besides the foregoing, a number of patents have been taken out in
connection with tandem compounding ; but as none of them have been
actually used, and the constructions are, as a rule, complicated,
detailed reference is hardly required.
CHAPTER X.
FOUR-CYLINDER TWO-CRANK SYSTEMS (OTHER
THAN TANDEM).
CONTENTS : The Vauclain Superposed Cylinder System The Johnstone
Annular Cylinder System.
SYSTEMS of this class may be classed in two main divisions. In the
one case the two cylinders at each side are more or less independent,
yet drive on to the same crank pin ; in the other case they are in
conjunction, but arranged in such a manner that they cannot be
classed as tandem compound engines, though corresponding thereto
in large measure.
As regards the first class, several schemes were mentioned in
Chapter IV., and a number of other like schemes have been patented
or published in the technical press from time to time, but none of
them have been employed in practice.
The Vauclain System. As regards four-cylinder two-crank
systems wherein the two cylinders at each side are in close connection,
so that the two pistons work together and one crosshead serves for
the two, by far the most important is the Vauclain, introduced by the
well-known Baldwin Works of Philadelphia, and this system, though
now superseded to some extent by a four-cylinder balanced system
(see Chapter XII.), has been used for some thousands of engines.
The Vauclain system consists in superposing a high- and a low-
pressure cylinder at each side of the engine, the two piston rods in
each case being attached to one large crosshead with a single con-
necting rod, so that only one set of motion and a single valve (of the
piston type) are required.
Anticipatory schemes have at one time and another been unearthed
from the patent records and from technical journals, and it may be
said that the Mallet-Lapage double low-pressure cylinder system
contains the germ of the idea ; but in practice, the Vauclain system
stands alone, for no other builders than the Baldwin Works turn out
engines thus compounded, and yet the system has probably as many
representatives, widely scattered, as any other system.
The first engine on this system was an otherwise ordinary four-
coupled bogie (American type) locomotive for the Baltimore and Ohio
114
FOUR-CYLINDER TWO-CRANK SYSTEMS (OTHER THAN TANDEM). 115
Railroad, a railway historically famous as the scene of many
locomotive triumphs and daring experimental innovations in the
early railway days of America, the engine being put in service in
1889. The cylinder ratio generally employed by Mr Vauclain is
about 3:1. Since its introduction the Vauclain system has been
applied to thousands of locomotives of all types, and these engines
have been supplied, outside the United States and other American
States, to Russia, China, Japan, France, India, Italy, Egypt, Australia,
and New Zealand.
Some of the Vauclain engines have wonderful records, and there
are few engines better known in Great Britain than these, although
this country does not possess a single representative of its own.
This system has been applied to locomotives of practically every
type now in use, and also to compressed-air locomotives for mine
FIG. 98. Vauclain Compound Compressed-air Mine Locomotive.
and elevated railway service, and to rack, and combined rack and
adhesion, locomotives.
Fig. 98 illustrates the application of this system to a compressed-
air mine locomotive for the Philadelphia and Reading Coal and Iron
Company. It is believed that the Vauclain is the only compound
system which has ever been employed for such engines, or for very
small engines such as four-wheeled shunting engines, while examples
of compound tramway engines of other systems are very rare.
Fig. 99 is an interesting front view of a large Vauclain compound
engine, and well indicates the arrangement of cylinders and valve
chests.
Figs. 100, 101 comprise two views showing cylinder and valve chest
castings formed in one with a half saddle for supporting the engine
smokebox. With the low-pressure cylinder below, the engine is for
passenger service ; when the high-pressure cylinder is below, the
engines are adapted for freight traffic, or have small coupled wheels.
Fig. 102 shows a pair of cylinders fitted up for use.
116
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
The principal objects which Mr Vauclain had in view when
introducing this system are best set forth in the following statement
furnished by the Baldwin Works, of which Mr Vauclain is Chief
Engineer :
1. To produce a compound locomotive of the greatest efficiency, with
the utmost simplicity of parts and the least possible deviation from
FIG. 99. Front View of Vauclain Compound Locomotive.
existing practice. To realise the maximum economy of fuel and water.
2. To develop the same amount of power on each side of the
locomotive, and avoid the racking of machinery resulting from
unequal distribution of power.
3. To ensure at least as great efficiency in every respect as in a
single-expansion locomotive of similar weight and type.
4 To ensure the least possible difference in cost of repairs.
FOUR-CYLINDER TWO-CRANK SYSTEMS (OTHER THAN TANDEM). 11?
5. To ensure the least possible departure from the method of
handling single-expansion locomotives ; to apply equally to passenger
or freight locomotives for all gauges of track, and to withstand the
rough usage incidental to ordinary railroad service.
FIGS. 100 and 101. Cylinder ^Castings for Vauclain Compound System.
Fig. 103 is a diagrammatic drawing showing the arrangement of
cylinders, slide valve, and steam ports, a specimen route for the
steam being traced by arrows.
The valve employed for controlling the steam distribution of each
pair of cylinders is of the piston type, working in a cylindrical
FIG. 102. Cylinders and Fittings for Vauclain Compound System.
steam chest formed in the saddle of the cylinder casting between
the cylinders and the smokebox, and arranged as close to the
cylinders as possible.
The valve, which is of the piston type, is double and hollow, and
118
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
is so formed that it controls the steam distribution of both cylinders ;
and as the supply of steam for the high-pressure cylinder enters the
steam chest at both ends, the valve is perfectly balanced, except for
the slight variation caused by the area of the valve stem at the back
end. It is claimed that this variation is an advantage in case the
valve or its connection to the valve rod should be broken, as it holds
SHUT
FIG. 103. Diagram of Steam Distribution in Vauclain Four-cylinder Compound.
them together ; and cases are reported where compound locomotives
of this type have hauled passenger trains long distances with broken
valve stems and broken valves, the parts being kept in their proper
relation while running by the compression due to the variation
mentioned. To avoid the possibility of breaking, it is the present
practice, however, to pass the valve stem through the valve and
secure it by a nut on the front end.
FOUR-CYLINDER TWO-CRANK SYSTEMS (OTHER THAN TANDEM). 119
Cast-iron packing rings are fitted to the valve and constitute the
edges of the valve. They are prevented from entering the steam
ports when the valve is in motion by the narrow bridge pieces across
the steam ports of the bushing.
When the low-pressure cylinder is on top it is usually necessary
to fit direct valve motion, but when the high-pressure cylinder
occupies that position a rocking lever and indirect valve motion
are employed, as usual in American practice.
It is obvious that to enable a Vauclain compound engine to start
a heavy train it is necessary to admit boiler steam to the low-
FIG. 104. Starting Valve for Vauclain Compound System.
pressure cylinder as well as to the high-pressure cylinder, and this is
provided for by the valve shown in figs. 104, 105, and 106. It is
merely a by-pass valve, which is opened to allow steam to pass from
one end of the high-pressure cylinder to the other end, and thence
through the exhaust to the low-pressure cylinder. This is more
clearly shown in figs. 105 and 106. The same cock acts as a cylinder
cock for the high-pressure cylinder, and is operated by the same
lever that operates the ordinary cylinder cocks, thus making a simple
and efficient device, and one that need not become disarranged.
The air valves C and C' are placed in the steam passages of the
low-pressure cylinders to supply air for preventing the formation of
a vacuum when running with steam shut off.
The hollow valve stem shown in fig. 107, which represents a
120
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
modified arrangement, accomplishes the same result, but with a
more direct action, and is preferable for fast service. The check
valve at the end of the hollow stem outside the steam chest is closed
by the pressure of the steam, but stands open when the pressure
FIGS. 105 and 106. Starting Cock for Vauclain Compound System.
is relieved and air is allowed to pass into the valve through the
perforation in the hollow stem. This arrangement also prevents the
accidental starting of an engine because of a leaky regulator valve.
In such a case slowly escaping steam will pass through the hollow
stem to the open air without creating pressure in the cylinders.
FIG. 107. Modified Starting Valve for Vauclain Compound System.
Water relief valves are fitted at each end of the low-pressure
cylinder.
The Johnstone Annular Cylinder System. In this section must
also be included the annular cylinder system of Mr F. W. Johnstone
FOUR-CYLINDER TWO-CRANK SYSTEMS (OTHER THAN TANDEM). 121
on the Mexican Central Railway. According to this arrangement,
each high-pressure cylinder is placed within a large low-pressure
cylinder, so that the latter is annular, as shown in fig. 108. On
the Mexican Central Railway there are very heavy grades, and
powerful engines are needed. The first annular cylinder engine
was a Rogers locomotive of the Consolidation type, converted about
1890.
The low-pressure piston had two piston rods which were connected,
with the high-pressure piston rod, to one crosshead. The tests were
very satisfactory, and it was claimed for the engine No. 66 that
an all-round increase in economy of 20 per cent, was effected.
In 1891 ten engines of the ten-wheel type, six-coupled with
leading bogie, and compounded according to this system, were
ordered from the Rhode Island Locomotive Works. Three more of
these compound engines, but of a special and unique design (see
Chapter XIV.), were afterwards built, making fourteen in all, and
FIG. 108. Section of Cylinders Johnstone Annular System.
these represent the total number of annular compound locomotives
on that or any other line.
The steam ports are so arranged that a single slide valve having
an internal passage controls the steam distribution of each pair of
cylinders. The slide valve is really of duplex construction, though
both portions are mounted on the same rod, but the inner portion
has independent play of about an inch along the rod, for the
purpose of giving a later cut-off in the low-pressure cylinder and
relieving compression in the high-pressure cylinder. The inner
valve is cushioned to prevent knocking by two springs, one on
either side.
To assist starting, a three-way cock is fitted in the driver's cab,
whereby boiler steam can be admitted by a small pipe to the steam
chest, so as to reach the low-pressure cylinder. Steam for use in
the low-pressure cylinder reaches the interior of the outer portion
of the slide valve by a pipe attached to the centre of the steam
chest cover, a corresponding opening being formed in the valve to
allow steam to pass.
CHAPTER XI.
FOUR-CYLINDER BALANCED SYSTEMS.
CONTENTS : Introductory Remarks The Webb Four-cylinder SystemThe Gols-
dorf Four-cylinder System Four-cylinder Italian System Smith Four-
cylinder System Von Borries Four-cylinder System Maffei Compound
Engines Compound Locomotives on the Lancashire and Yorkshire Railway
Balanced Compound Locomotives on the Hungarian State Railways.
Introductory Remarks. As already mentioned, four-cylinder four-
crank systems (other than articulated engines) may be divided into
two main divisions : (1) wherein all four cylinders actuate the same
axle, and (2) wherein two cylinders drive one axle and two another,
the two sets of coupled wheels being in most cases coupled.
Strictly speaking, systems of the one class can be adapted, with
practically no change other than constructional, from one division
to the other, and in a few instances this has been done, but for
convenience the present chapter deals with systems which have been
applied only according to the first class. Where a system has been
employed in both ways, description is reserved until the following
chapter, as in nearly every instance the " divided " engines are the
most important.
The four-cylinder " balanced " systems derive their name because
of the fact that as the four cylinders drive separate cranks, the
cranks can be distributed round the circle of revolution, at or about
angles of 90 apart, and are so arranged that one crank is opposite
another ; consequently, the moving parts are very largely balanced,
and as there are eight impulses per revolution, fairly evenly dis-
tributed, the turning moment can be made very regular, and the
engines made very efficient.
That this is so appears to be becoming extensively realised, for
four-cylinder balanced compound engines are becoming well-nigh
universal, either with the cranks all on one axle, or with two driving
axles according to the "divided and balanced" system. In fact,
almost all recently designed compound engines belong to one or
other of these classifications. It is true that four cylinders operating
separate cranks necessitate the use of four sets of motion, and in
many cases four sets of valve gear, but it is realised nowadays that
122
FOUR-CYLINDER BALANCED SYSTEMS.
123
the additional first cost and apparent complication is more than
justified by the advantages attending the use of such engines, and
some engineers are even designing four-cylinder non-compound
engines on similar lines for the sake of improved balancing and the
division! of work over two axles.
The Webb Four-cylinder System. In 1898 Mr F. W. Webb
introduced the first of a class of four-cylinder compound engines for
express service on the London and North- Western Railway. In
these engines, not only had they four cylinders, but- instead of
dividing the work done over two axles, as in the case of the three-
cylinder locomotives (see Chapter VIII. ), all four cylinders were
arranged to drive one axle by cranks 90 apart, this axle being
coupled with another axle, the wheel type being that known as the
4-4-0, or four-coupled bogie type. Strictly, the bogie is a double
radial truck, as there is no centre pivot pin.
At first two engines were built to the same design, except that
one was a compound with two high-pressure cylinders outside the
FIG. 109. Slide Valves Webb Four-cylinder System.
frames and two low-pressure cylinders inside the frames, and the other
had four cylinders all receiving boiler steam. After extended trial,
the non-compound engine was altered to compound, and thirty-eight
further compound engines were built. In 1900-2 another series of
forty engines were built, having slightly larger high-pressure cylinders
and augmented boiler power, the steam pressure being also raised
in some cases. In 1901-2 the system was applied for eight-coupled
mineral engines, otherwise similar to the three-cylinder engines
already described, and in 1903-4 a class of small-wheeled six-coupled
bogie engines were introduced for mixed traffic purposes.
A feature of Mr Webb's four-cylinder system is the fact that only
two sets of valve gear are employed for four cylinders, and fig. 109
shows the mechanism used for transferring the movement of the
directly operated low-pressure valve spindle to the corresponding
high-pressure valve spindle in opposite degree as required, as the
pistons of adjacent low- and high-pressure cylinders are always
moving oppositely, and the slide valves therefore require to be
correspondingly operated.
It has been maintained by many engineers that these engines
124 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
were not designed in a way to give really effective results, principally
in respect of the apparently inaccurately proportioned cylinders, the
non-provision of means for admitting boiler steam to the low-pressure
cylinders at starting, and the impossibility of independently adjusting
the valve operation of the high- and low-pressure cylinders respectively.
As no means for non-compound starting are provided, the high-
pressure cylinders are necessarily somewhat larger than they should
be in proper proportion to the low-pressure cylinders. According to
generally accepted ideas, the cylinder diameters should be about
13 and 22 in. diameter, but in order that the H.P. cylinders should
be able to start a train alone, Mr Webb employed the diameters
of 15 or 16 in. and 22 in.
In practice, however, notwithstanding the many adverse criticisms
which were advanced, and the general inclination which has been
shown since Mr Webb's retirement to describe them as failures and
unsatisfactory engines, it cannot be denied that they have done
much splendid work ; and their everyday performances, if not
altogether such as are required for dealing with average requirements
on the London and North- Western Railway, compare very favourably
with work done on other lines with apparently more powerful engines,
where the duties are not so systematically onerous.
Since the accession of Mr Whale to the position of Chief Mechanical
Engineer of the London and North-Western Railway, most of the
larger series of four-cylinder compound express locomotives have
been fitted with additional valve gear for the high-pressure cylinders,
means being provided whereby the high- and low-pressure valve
gears can be adjusted independently if desired; and it is stated that
the result has been a remarkable improvement in the working of
these engines.
Grb'lsdorf Four-cylinder System. Since about 1900 Herr K. von
Gblsdorf has been adapting his well-known two-cylinder system to
four-cylinder engines, and fig. 110 is a cross section through the
cylinders of one of his large Atlantic type express engines for the
Austrian State Railways. Since these were built the system has also
been applied to some large six-coupled express engines, with leading
and trailing pairs of carrying wheels (2-6-2 type).
The starting arrangements are similar to those employed for two-
cylinder engines as described in Chapter VII.
Four-cylinder Italian System. The year 1900 saw the construc-
tion of the first engine of a four-cylinder compound class of express
engine for the Adriatic system of Italian railways, which comprises
several notable features.
These engines are six-coupled bogie engines, but are adapted to
run in a reversed direction, the engine being of the trailing bogie
tank engine type, but arranged to travel with the footplate end in
front and the chimney behind, a cylindrical tank tender being
employed for water, and the coal being carried in the engine
bunkers.
This arrangement has a special advantage that the driver has an
FOUR-CYLINDER BALANCED SYSTEMS.
125
uninterrupted view ahead, and that a very steady-running engine
is produced.
Fig. Ill is an interesting photograph showing the cylinders and
valve chests (for piston valves).
The cylinder arrangement employed for these engines is very
peculiar, there being two high-pressure cylinders on one side of
the longitudinal centre line, and two low-pressure cylinders on
FIG. 110. Golsdorf Four-cylinder System Cross Section.
the other side. The cylinder arrangement is therefore H.P., H.P.,
L.P., L.P.
The steam distribution is controlled by a special piston valve
located over each outside cylinder, and controlling the steam
passages of each pair of cylinders, one valve serving for both high-
pressure cylinders, and the other for both low-pressure cylinders,
the ports being crossed in some cases to allow of this. Two valves
only are employed, so that two sets of valve gear are sufficient.
The inside cylinders (one H.P. and one L.P.) are higher than the
outside cylinders, their piston rods being inclined to clear the
126
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
coupled axle under the smokebox, so that all cylinders operate the
middle coupled axle.
It is difficult to understand why an arrangement involving such
complicated cylinder castings should be employed, but it is stated
that these engines, which are now fairly numerous, are doing very
good work. Practically, the arrangement is that of a two-cylinder
I I
compound engine with each cylinder duplicated, one piston of each
pair always working oppositely to the other, and driving cranks 180
apart.
For starting, a small slide valve is connected to the H.P. valve
rod and works over ports admitting boiler steam to the receiver, but
the steam pipe for this admission is connected to the regulator valve,
so that it is only when the regulator is opened to a certain degree
FOUR-CYLINDER BALANCED SYSTEMS. 127
(about one-sixth open) that steam can pass to the receiver by this
means, the engine working compound when the regulator is opened
further. This design was prepared by Signor Planchar of the
Southern Railway of Italy.
Smith Four-cylinder System. The Smith three-cylinder system
has already been described in Chapter VIII. During 1906, however,
the system has also been adapted to four-cylinder engines, designed
by Mr Worsdell for the North-Eastern Railway, and one of these
engines is illustrated in the frontispiece.
Von Berries Four-cylinder System. In 1903 a notable engine
was built by the Hanover Engine Works, primarily for exhibition
at St Louis in 1904, but also for participation in official trials of
steam locomotives held in Germany at the beginning of the same
year, the engine being a four-cylinder compound engine designed
by Herr von Borries. Since that date a number (about fifty) of
similar engines, which are also fitted with the Pielock superheater
(see Chapter XV.), have been supplied for service on German
Railways
The two high-pressure cylinders are placed between the frames,
the low-pressure cylinders being outside. Each pair of high- and
low-pressure cylinders is cast in one piece, with their corresponding
steam chests. The two groups of cylinders are bolted together and
carry the smokebox. The valves of the H.P. cylinders are piston
valves with inside admission, those of the L.P. cylinders balanced
Trick valves.
The cranks of the H.P. and L.P. cylinders upon the same side of
the engine are set at an angle of 180 with each other, the cranks
of the two sides being at right angles to each other.
The valve gear is of the Heusinger-Walchaert type, and both
valves on one side of the engine are driven by a single gearing.
The two valves are controlled by a single link, which receives its
motion from one eccentric, but the stem of each valve is coupled to
an advance lever, which receives its motion from the crosshead of
the corresponding piston.
For the outside valve the link movement is transmitted by a lever
with arms of different length, so proportioned that the ratio of
steam admission is 55 : 30 for L.P. and H.P. cylinders in forward
and backward gear.
The starting is effected smoothly and without any difficulty by
a direct admission of live steam into the steam chests of the low-
pressure cylinders. Fig. 112 is a horizontal section showing the
valve chests and starting valves for a high- and a low-pressure
cylinder. The hollow intercepting valve is shown in position for
non-compound working. The high-pressure exhaust passes by the
passage a through the interior of the valve b to the opening c, and
thence to the passage d leading to the exhaust. At the same time
boiler steam is admitted by the passage e and by the recess / of the
valve b to the passage #, by which it enters the low-pressure steam
chest. For compound working the valve b is rotated so that a
128
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
passage-way is opened for the H.P. exhaust steam to pass from the
interior of the valve b through the opening h to the low-pressure
steam chest, and the boiler steam supply is cut off.
There are two valves b, one at each side of the engine, but they
are operated together by mechanism under the driver's control.
Maffei Compound Engines, Bavaria and Baden State Railways.
These engines, of the Atlantic (4-4-2) type, were first introduced
in 1903, and were also designed to some extent in connection with
the official steam locomotive trials conducted in Germany. They
are now employed in considerable numbers on the Bavarian and
Baden State Railways, together with some engines differing only in
the fact that a third pair of coupled wheels are substituted for the
trailing carrying wheels. The system has also been applied to some
!
>^T.^
__j
c
f-
<.
a
1
FIG. 112. Von Borries Four-cylinder System Valve Chests and Starting Valves.
large engines of the 4-4-4 type, having a bogie under the firebox as
well as at the leading end, and four coupled wheels.
Fig. 113 is a cross section of one of these engines for the Bavarian
State Railways. All four cylinders are in line underneath the smoke-
box. The H.P. cylinders are fitted with piston valves. The outside
low-pressure cylinders are provided with balanced slide valves having
double admission and exhaust ports.
The low-pressure cylinders are each connected with the high-
pressure cylinders by short double pipes. The valve motion is
outside and actuates the low-pressure valves directly, the high-
pressure valves being operated from the same motion by means of a
rocking lever.
To ensure economical working of steam, the proportion between
the high- and low-pressure piston areas has been made 1 : 2'9.
For starting the engine there is a valve worked from the reversing
UNIVERSITY
OF
FOUR-CYLINDER BALANCED SYSTEMS.
129
gear and admitting live steam up to a pressure of 9 atmospheres
into the receiver, which is fitted with a safety valve corresponding
to that pressure. The arrangement is very similar to that described
in Chap. VII.
In order to prevent a vacuum in the cylinders when running
with the regulator closed, automatic vacuum valves are provided,
FIG. 113. Cross Section Maffei Four-cylinder Compound Locomotive.
and these actuate smaller valves, which admit steam at low-pressure
to the cylinders for lubrication. In the front and back covers of
the high-pressure cylinders there are safety valves, which prevent
damage to the cylinders through condensed water.
Compound Locomotives on the Lancashire and Yorkshire
Railway. On this railway an engine was adapted a few years ago
as a four-cylinder compound engine, the arrangement being similar
to that employed by Mr Webb on the L.N.W.R., but the cylinder
9
130 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
diameters being 14 and 22 inches. Quite recently an eight-coupled
engine has been adapted as a four-cylinder compound engine by Mr
G. Hughes, Locomotive Superintendent. All cylinders operate one
pair of wheels.
For starting, a small slide valve is employed controlling ports
whereby boiler steam can be admitted to the L.P. steam chests.
Four-Cylinder Compound Locomotives for the Hungarian State
Eailways. Towards the close of 1906 a series of powerful express
locomotives was placed in service on the Hungarian State Railways.
They are of the Atlantic type, with the four cylinders all actuating
the leading pair of coupled wheels. The low-pressure cylinders are
outside, and all cylinders are provided with piston valves. Two
sets of valve gear only are employed. The starting mechanism,
permitting of non-compound working, is an adaptation of that
described in Chapter V. in reference to two-cylinder compound
engines, and illustrated by fig. 43.
CHAPTER XII
FOUK-CYLINDER DIVIDED AND BALANCED SYSTEMS.
CONTENTS : General Remarks The de Glehn System Vulcan Foundry Engine
(de Glehn System) for Great Northern Railway De Glehn Compound Engines
for Portuguese Railways, built by A. Borsig The Henri-Baudry System The
Vauclain Balanced System The Cole System Ivatt's Compound Engine for
Great Northern Railway Compound Engines in Belgium.
General Remarks. Four-cylinder systems of this class appear to
be now in greatest favour in most countries, for a large proportion
of the four-cylinder compound engines introduced since the com-
mencement of the twentieth century belong to this class.
In France, nearly all compound engines now built are four-
cylinder divided and balanced engines according to the de Glehn or
the Henri-Baudry systems, and, with variations introduced by the
firms of A. Borsig, J. A. Maffei, and the Swiss Locomotive Works, the
systems employed are very similar, these engines being found in
Germany, Switzerland, Spain, and Portugal, as well as in some of the
smaller European States. In Belgium compound engines are very
few, but most of them can be placed in this section.
In the United States the new Yauclain system, though first
introduced as a balanced system, all cylinders driving one axle, is
frequently adapted as a "divided and balanced" system, for which
reason it is described in this chapter ; and the Cole system, which is
the other of the two American four-cylinder systems now employed,
is also " divided and balanced."
Strictly speaking, there is very little difference between four-
cylinder " balanced " and four-cylinder " divided and balanced," for
it is only necessary to adapt the cylinders (they need not always be
separated) to drive separate coupled axles to transfer a design from
one class to another, though in most cases the divided system is less
adaptable for the use of two sets of valve gear only.
The de G-lehn System. The first locomotive compounded accord-
ing to Monsieur de Glehn's system was an engine designed in 1885
for the Northern Railway of France. It had two high-pressure
cylinders inside driving the front driving axle ; and two outside low-
pressure cylinders, set back on the frames, driving the rear pair of
131
132
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
driving wheels. The axles were not coupled, in which respect
de Glehn followed Mr Webb's practice ; and it is worthy of note that,
although in all subsequent engines coupling rods have been employed,
this engine is still at work with uncoupled wheels.
FIG. 114. Cross Section de Glehn Four-cylinder Compound Express Locomotive.
The engine was shown at the Paris Exhibition of 1889. A few
years ago a bogie was substituted for the single leading axle ;
otherwise the engine is still in its original condition, though, of
course, it has long since been taken off first-class work.
It was not, however, until 1891 that Monsieur de Glehn, in
collaboration with Monsieur du Bousquet, Chief Engineer of the
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
133
Northern Railway of France, really in-
troduced the system, now universally
known; but from that date onwards it
has been employed very extensively, first
on the Northern Railway of France, and
then, with but slight modification, on
all the other French railways except the
Paris, Lyons, and Mediterranean Rail-
way, while the system has also been
used for large numbers of engines for
Germany, Switzerland, Spain, Portugal,
Belgium, Alsace, some of the Balkan
States, Asia Minor, etc., and a few en-
gines in England, United States, Egypt,
China, etc.
In fact, the de Glehn system is prob-
ably the most extensively used of any,
and in many cases the engines have been
built quite independently of Monsieur
de Glehn. The total number of these
engines is now considerably over 2000,
of various designs.
As a rule, the cylinders are arranged
in two sets, one pair outside (usually
the high-pressure cylinders), set back
somewhat on the frames, and actuating
the second coupled axle, and the other
pair inside, under the smokebox, and
driving the leading coupled axle. In
some cases, however, the cylinders are
placed in line, though separate axles are
driven, the outside piston and connect-
ing rods being much longer than those
inside, to permit of this. For some of
the goods engines, the inside cylinders
drive the second coupled axle, and the
outside cylinders the third axle.
Fig. 114 is a cross section through
the low-pressure cylinders of one of the
large express engines of the Northern
Railway of France, and fig. 115 is a
half-sectional plan showing the cylinders,
and motion thereof.
From these views it will be seen that
there are four sets of valve gear of the
Walschaert type, those outside employ-
ing a return crank and those inside
a single eccentric. A feature of the
de Glehn system is the fact that the
i S1r~
134 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
respective valve gears can be independently adjusted to vary the
relative cut-off ratios of the H.P. and L.P. cylinders.
In some of the early engines the cranks of the H.P. and L.P.
cylinders at each side are placed 165 apart, but the general practice
now is to place them at 180 apart, as usual, according to other
systems.
To enable the engine to start with boiler steam in the low-pressure
cylinders, or for working as a four-cylinder non-compound engine
temporarily when very great power is required, a valve is provided
by which boiler steam can be admitted, past a reducing valve, to the
low-pressure cylinders, and an intercepting valve is fitted whereby
the high-pressure cylinders exhaust to the blast pipe instead of to
the receiver pipe when working non-compound. The intercepting
valve is operated by a small steam motor (" servo "-motor) controlled
by a three-way cock in the driver's cab.
Fig. 116 represents a series of diagrammatic drawings published by
the Locomotive Magazine, and reproduced here by permission, which
well indicates the principal features of this system. The locomotive
shown in outline is the first of three French-built locomotives in use
on the English Great Western Railway.
In the driver's cab is the three-way cock already referred to, and a
steam valve by which steam is admitted to the reducing valve, and
thence to the low-pressure steam chests.
The intercepting valve is in the form of a long hollow cylinder
located alongside each of the low-pressure steam chests.
Diagram lS T o. 1 shows the valves with the engine working non-
compound. The valve A is operated to allow steam to pass to the
reducing valve E, and the valve B allows steam to pass to a small
cylinder D, where it acts on a piston which rotates the cylindrical
valve C to allow H.P. exhaust steam to pass to the blast pipe. When
altered for compound working the three-way cock B (diagram 2) is
moved so that steam passes to the other end of the cylinder D, and
causes the piston therein to rotate the valve C to a position wherein
the H.P. exhaust steam is allowed to pass through the interior of the
valve C to the low-pressure steam chests. The references are
marked with one or two dashes for the two positions.
By means of the intercepting valve C, the driver can operate the
engine with the low-pressure cylinders alone in case of accident.
In most respects the arrangement corresponds very closely to that
employed for the du Bousquet tandem compound tank engines,
described in Chapter IX. ; indeed, the latter is directly derived from
the methods introduced by Monsieur de Glehn.
Fig. 117 is a separate enlarged view showing the construction of
the cylindrical intercepting valve.
According to an earlier construction of the de Glehn intercepting
valve, the valve is a short cylinder acting as an ordinary three-way
cock controlling the passage of the H.P. exhaust steam either to the
low-pressure steam chest or to the blast pipe.
Figs. 118 and 119 are views reproduced from a recent number of
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
135
136
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
Engineering, which very clearly set forth the main features of the de
Glehn system as employed in recent engines of the Eastern Railway
of France.
The system is not altered from that already described, but
the constructive arrangements are
somewhat different, though re-
sulting mainly from the employ-
ment of piston valves, and from
the use of compressed air for
operating the intercepting valve
instead of steam.
Vulcan Foundry Engine (de
Glehn System) for Gt. Northern
Railway. During 1905 an en-
gine was built in Great Britain
by the Vulcan Foundry Company,
Limited, of Newtoii-le-Willows,
under unusual circumstances.
The Directors of the Great
Northern Railway invited tenders
for a powerful express locomotive
for purposes of comparison with
their own engines, the builders
having practically a free hand as
regards design, and the order was
obtained by the firm mentioned.
The engine is a four-cylinder
compound engine of the Atlantic
type, compounded according to
the de Glehn system. As regards
essentials, the starting mechanism
corresponds to that already de-
scribed, the difference being al-
most entirely constructional, but
the driver's lever for controlling
non-compound working is so ar-
ranged that it changes automati-
cally to compound as soon as the
driver lets go of the lever.
De Glehn Compound for Portu-
guese Railways, built by A. Bor-
sig. It has already been stated
that the de Glehn system has been
employed by several Continental
locomotive building firms, and fig.
120 is a view showing the con-
struction of intercepting valve and operating mechanism therefor,
as fitted by the well-known firm of A. Borsig of Berlin to some
notable six-coupled bogie engines for the Portuguese State Railways.
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
137
In this construction, the intercepting valves are of the three-way
type mentioned, and the view also shows the small operating
cylinder by which they are operated, and the connections.
The Henri-Baudry System. Early in 1889 M. Henri, Locomotive
Engineer of the Paris, Lyons, and Mediterranean Railway, entered the
field with a compound system which developed for some years in
advance of the de Glehn system, and which probably entitles
M. Henri to far greater credit than is usually assigned to him.
FIG. 118. De Glehn System Eastern Railway of France. Reproduced
from Engineering.
Six engines were built according to this system, of three distinct
types. In these engines coupling rods were employed, in which
respect M. Henri was certainly ahead of M. de Glehn, and, what
is most important, a high steam pressure was used 213 Ibs.
instead of 156 Ibs. as used in de Glehn's system ; but the cylinder
arrangements were very unusual. Later engines for the Paris,
Lyons, and Mediterranean Railway were built according to one of
these arrangements, but such dispositions of the cylinders have
never since been repeated elsewhere, and even the one arrangement
referred to has been discontinued for some years.
The type designed for passenger use had the four cylinders
138
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
abreast, but driving on to separate axles, the inside high-pressure
cylinders driving the front coupled wheels, and the outside low-
pressure cylinders driving, with long piston and connecting rods, the
rear coupled wheels. Two of these engines were built, and one of
them was exhibited at the Paris Exhibition of 1889, forming an
interesting companion to Monsieur de Glenn's engine above described.
The second type was an eight-coupled goods engine, with the
outside low-pressure cylinders in the usual positions, driving the
second axle, and with the inside high-pressure cylinders set back
between the frames an absolutely unique arrangement and driving
the third axle.
In the other two locomotives, also eight-coupled engines, all
cylinders were under the smokebox ; but the inside high-pressure
cylinders were raised and inclined and drove the second axle, while
<tion of Piston,
Starting,
'sit/on of Piston,
Compound Working
FIG. 119. De Glehn System, as employed on the Eastern Railway of
France. Reproduced from Engineering.
the outside low-pressure cylinders were fitted with long connecting
rods to drive the third axle. These engines, according to a state-
ment made by M. Baudry, successor to M. Henri, proved very
successful, owing, it is claimed, principally to the high steam
pressure employed, and paved the way for an extensive adoption
of the compound system for locomotives on the Paris, Lyons, and
Mediterranean Railway.
Commencing in 1893, a number of other eight-coupled engines were
built having the cylinders arranged according to the second type
above described. In 1892 was built the first of fifty eight-coupled
engines having all cylinders driving the second axle, thus constituting
a four-cylinder balanced (not divided) design.
In 1892 three engines were constructed, two of which were of the four-
coupled bogie type, and the third four-coupled with a single leading
axle, in which the low-pressure cylinders were inside and drove the front
coupled axle, and the outside high-pressure cylinders were set back
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
139
on the frames to drive the rear coupled axle, thus conforming to the
cylinder arrangement generally associated with Monsieur de Glenn.
In 1894 M. Baudry built forty
more four-coupled bogie engines
of the same type, and since then
further engines of various types
on the same lines have been
built as required, the Henri and
the de Glehn systems having by
this time converged until the
differences became those of de-
tail design or in matters outside
the present subject.
For many years these bogie
four - coupled engines and a
corresponding class of small
wheeled six-coupled bogie en-
gines have been employed on
the Paris, Lyons, and Mediter-
ranean Railway, but in 1904
Monsieur Baudry introduced a
large-wheeled six-coupled class
of engine on the same system
for heavy express traffic.
The cylinders are all placed
very nearly in line, but the con-
necting rods of the outside high-
pressure cylinders are much
longer than those of the inside
cylinders, so as to actuate the
second coupled axle.
For all these compound en-
gines provision is made by
means of a special design of
reversing gear for the indepen-
dent adjustment of the high-
pressure valve gear, but, as a
rule, according to this system
the low-pressure cut-off ratio is
invariable, as Monsieur Baudry
considers this method of opera-
tion preferable.
For starting purposes, a simple
valve is fitted whereby boiler
steam can be admitted to the low-
pressure cylinders at starting.
The Vauclain Balanced System. This system, introduced by the
Baldwin Works of Philadelphia, has in large measure superseded
the superposed cylinder system described in Chapter IX. It admits
140
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
of employment as a "balanced" system, or as a " divided and
balanced " system ; and although it was first introduced according
to the former method, it is now as often employed in one way
as in the other, and the large number of engines of this system
now in use are about equally divided between the two classes. In
practice, the only difference is that when "divided" the outside
cylinders have long connecting rods to drive an axle behind that
operated by the inside cylinders.
The first locomotive of the four-cylinder balanced compound system
was built in January 1902 for the Plant System of Railroads,
as the twenty-thousandth locomotive built by the Baldwin Loco-
motive Works after seventy years of continuous operation. This
locomotive was, however, too heavy for use on the Plant System
FIG. 121. Cylinder and Valve Castings for Vauclain Balanced System.
and was sold to the Chicago Short Line. It was of the ten-wheel
(4-6-0) type.
As is common to locomotives of this system, the low-pressure
cylinders are placed outside the engine frames, connections being
made with crank pins on the driving wheels. The high-pressure
cylinders are located inside the frames in the same horizontal plane
as the low-pressure, and connection is made with a cranked driving
axle. In the first locomotive referred to all four connecting rods
are coupled with the front axle.
The cylinder saddle is cast in two parts (fig. 121) and bolted
together in the usual way, each half containing a high- and low-
pressure cylinder and a single valve which controls the admission of
steam to both cylinders. This admits of the use of the ordinary
Stephenson type of valve motion, the same as is used in single
expansion locomotives. The valve is of the piston type, with central
steam admission, and slides in a machined bushing, which is forced
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
141
into the cylinder saddle. A single reverse lever in the cab is all
that is required for governing the valve motions of all cylinders.
The course of the steam from its admission to the high-pressure
cylinder until the final exhaust is shown by the diagram reproduced
in fig. 122.
The live steam port in this design is centrally located between the
induction ports of the high-pressure cylinder. Steam enters the
(STARTING VALVE
FIG. 122. Steam Distribution in Balanced Compound Cylinders.
high-pressure cylinder through the steam port and the central ex-
ternal cavity in the valve. The exhaust from the high-pressure
cylinders takes place through the opposite steam port to the interior
of the valve, which acts as a receiver. The outer edges of the valve
control the admission of steam to the low-pressure cylinder. The
steam passes from the front of the high-pressure cylinder through
the valve to the front of the low-pressure cylinder, or from the back
of the high-pressure to the back of the low-pressure cylinder. The
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS. 143
exhaust from the low-pressure cylinder takes place through external
cavities under the front and back portion of the valve, which com-
municate with the final exhaust port. The starting valve connects
the two live steam ports of the high-pressure cylinder to allow the
steam to pass over the piston.
In many engines, although the cylinders are located in line, the
piston and connecting rods are of different lengths, so that separate
axles are driven by each pair of cylinders, the arrangement then
being that of " divided and balanced."
In all cases the parts are so arranged that on each side of the
engine, while the reciprocating parts in connection with the high-
pressure cylinder are moving in one direction, those in connection
with the low-pressure cylinder are moving in the opposite direction.
These parts having the same rate of speed, and being practically of
the same weight, exert an equivalent force in opposite directions at
all points and balance each other. This leaves only the revolving
parts to be compensated for in the driving wheels, and these can be
exactly counterbalanced. The two pistons on each side of the loco-
motive, travelling in opposite directions, equalise the longitudinal
strains^ and prevent what is termed the " nosing " action. This
relieves the track from injury, and adds to the safety of the loco-
motive and to the comfort of the engineer.
The crank on the axle and the crank pin in the driving wheel for
the corresponding high- and low-pressure cylinders are set at an
angle of 180, the two axle cranks being set at 90 ; this brings the
action of each high- and low-pressure cylinder on one side of the
locomotive, quartering with those on the other side, and four points
of connection are provided, equally distributed about the central
axis. This arrangement to a great extent neutralises the unequal
rotative moments due to the angularity of the main rods. Four sets
of rods, guides, and pistons are used, but the strains are so distributed
between them as to make it possible to lighten the weight of each,
and still have ample strength for maximum requirements. This
division of the strains decreases the wear and tear on the moving
parts and compensates for the increased number.
In some engines the inside cylinders actuate the same axle (the
second coupled axle) as the outside cylinders, and to enable the
inside connecting rods to work past the first coupled axle, looped
connecting rods are employed, the rods being adapted to embrace the
leading coupled axle.
The Cole System. During the past two years the American
Locomotive Company have been introducing the "divided and
balanced" four-cylinder compound system devised by Mr F. J.
Cole when Locomotive Engineer of the New York Central and
Hudson River Railroad.
The first of these engines is illustrated by line diagram and half-
sectional plan in fig. 124. In this engine the four cylinders are so
related that it has not been necessary to duplicate the valve motion,
or to depart in any way from the best previous accepted practice.
144
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS. 145
The use of four cylinders, two high-pressure and two low-pressure,
gives an opportunity for compounding under the most favourable
conditions ; and with each high-pressure piston working 180 from its
low-pressure piston, and the other pair working 90 from the first
pair, the successive impulses from the four cylinders produce a
remarkably uniform turning moment. This results in a much more
rapid rate of acceleration when starting up than has been possible
with two-cylinder engines.
In order to avoid the concentration of work on a single driving
axle, one pair of cylinders is connected to the forward axle and the
other pair to the rear axle. The high-pressure cylinders are placed
between the frames and located slightly in advance of the usual
position, so as to secure the necessary length for the connections,
crossheads, guides, connecting rods, etc. The forward axle is
necessarily a crank axle. The low-pressure cylinders are placed
outside, and connected in the usual way to crank pins on the rear
drivers.
With this relative arrangement of each pair of one high-pressure
and one low-pressure cylinders, both a high-pressure and a low-
pressure piston valve are carried by the same valve stem, the
intermediate portion of the valve chamber serving as a receiver
between the two cylinders.
Ivatt Compound Engine for Great Northern Railway. The
Vulcan Foundry engine on the de Glehn system for the Great
Northern Railway has already been mentioned earlier in this chapter,
but, besides this engine, Mr Ivatt has himself designed a four-cylinder
divided and balanced compound engine.
This engine, as regards the boiler and general dimensions, corre-
sponds with the standard non-compound engines of this railway.
The cylinders are arranged abreast, but drive separate axles, the
outside high-pressure cylinders actuating the rear coupled wheels,
while the low-pressure cylinders drive the leading coupled axle.
This engine also possesses the peculiarity that the stroke of the
high-pressure cylinders is only 20 in. (diameter 13 in.) as compared
with 26 in. (diameter 16 in.) for the low-pressure cylinders.
Walschaert valve gear is employed for the outside cylinders and
ordinary link motion for the inside cylinders. Two reversing levers
are employed with sectors placed close together on the footplate, and
the two sets of reversing gear can be operated either simultaneously
or independently of one another. Each reversing shaft is fitted with
a vacuum-locking device by which the gear can be locked in position.
The engine can be worked either as a simple or as a compound engine
by means of a change valve located over the low-pressure steam chest.
The valve is worked by a small auxiliary stearn cylinder in con-
nection with a water dashpot arranged so as to lock it either in the
simple or compound position.
Judging from the cylinder capacities of this engine it appears
that the main object in view is to provide an engine which can be
worked frequently as a non-compound, but whenever circumstances
146
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
are favourable, as when travelling on easy gradients or the level, and
when the train is well under weigh, can be used as a compound
engine with small steam consumption. Most four-cylinder compoiind
locomotives if worked non-compound for long would run the boiler
out of steam, whereas with the cylinder dimensions employed for
this engine the non-compound steam consumption is not excessive,
while compound working enables any economy that is possible to be
obtained at other times. The comparative performances of the two
Great Northern compound engines will therefore be peculiarly inter-
esting whenever official data is published.
Four-cylinder Balanced Compound Engines in Belgium. The
year 1905 has seen some notable developments in Belgian locomotive
practice, for, in connection with the Lie'ge Exposition, quite a number
of remarkable engines have been introduced for experimental trial,
and in several cases have been introduced into ordinary service.
Almost without exception these notable engines are of the six-
coupled bogie type, with comparatively small wheels, as very high
speed is but seldom required in Belgium, heavy loads over severe
gradients, at good though not excessive speeds, being the rule ; but
the engines are in every instance very large and powerful. In only
FIG. 125. Diagrammatic Plan View of Balanced Compound Locomotive
Belgian State Railways.
a few cases are the engines compound, but several of them are
fitted with superheating apparatus, as described in Chapter XV.,
and some of them combine both features.
Some of the compound engines are on the de Glehn divided and
balanced system already described, and correspond with standard
classes on French railways, but others are arranged with the four
cylinders driving the leading coupled axle.
Fig. 1 25 is a diagrammatic plan view of one of these engines, as
built by the John Cockerill Company of Seraing, and having all four
cylinders driving one axle. This engine has two sets of valve gear
operating the valves of four cylinders by means of a reversing
rocking lever, in the manner already described in reference to the
Webb four-cylinder system. The low-pressure cylinders are placed
outside.
For starting, the admission of boiler steam to the receivers is
automatically effected by a small differential valve which allows steam
to pass only so long as the pressure in the receiver is below 88
pounds per square inch, but which closes as soon as that pressure is
reached. The driver has, however, control of this valve, so that he
can prevent live steam admission if desired.
Another engine built by the same firm has the cylinders arranged
FOUR-CYLINDER DIVIDED AND BALANCED SYSTEMS.
147
to drive separate axles as shown in the diagrammatic plan view (fig.
126).
Some of the engines are fitted with superheating apparatus (see
Chapter XV.), and are adapted so that part of the superheater also
serves the purpose of a receiver superheater through which the
steam passes between the high- and low-pressure cylinders.
Another engine, having four cylinders abreast and driving the
FIG. 126. Diagrammatic Plan View of Divided and Balanced Engine
Belgian State Railways.
same axle, has been built by the La Meuse Company, and this, though
a non-compound engine, is adapted for ready conversion as a compound
engine.
Besides the four-cylinder divided and balanced engines described, a
few such engines have also been supplied to the Bavarian and Swiss
railways, which, while not corresponding exactly with the de Glehn
system, are compounded according to very similar systems.
CHAPTER XIII.
ARTICULATED COMPOUND ENGINES.
CONTENTS : Articulated Engines The MalletSystem Mallet Compound Engines
for St Gothard Railway Mallet Compound Engines for Russia Mallet
Compound Engines in the United States The Meyer-Lindner System
Compound Fairlie Engines The Johnstone Articulated Engine The Du
Bousquet Articulated System.
Articulated Engines. By the term "articulated," as applied to
locomotives, it is understood that the engine is so fitted that some of
the driving wheels can move into planes at an angle with those of
other axles, and this usually entails that the engine has two distinct
sets of coupled wheels, which are operated either from one set of
cylinders or from distinct cylinders, the engine being thus divided
into two driving sections capable of independent movement upon
very curved lines, notwithstanding that the wheel base is long.
Numerous designs for such engines have been employed at various
times, particularly for mountain and narrow-gauge railways on the
European Continent, and they may be classified in two divisions :
(1) those wherein all the wheels are coupled in somewhat the usual
manner, but some of the axles are capable of the requisite independent
angular movement (many of these designs are most ingenious, but
very complicated) ; and (2) those wherein the wheels are arranged in
distinct sets.
Engines of the former class have never been very numerous, and
all of them, so far as the writer is aware, have been simple engines.
In the second class, however, compounding has been employed
with success, and therefore extended consideration is required.
Engines of this class can be again divided into three main divisions :
(1) those having cylinders all fixed upon the frame, but driving one
series of coupled wheels directly and one series indirectly through
more or less complicated lever mechanism which allows of the
required independent angular movement of one set of wheels; (2)
those having two sets of coupled wheels, one set fitted in the engine
frames which carry their operating cylinders, while the other set are
fitted in a bogie frame and usually carrying operating cylinders
therefor ; and (3) those wherein two pivoted bogie trucks, each with
a set of coupled wheels and a set of cylinders, are employed.
148
ARTICULATED COMPOUND ENGINES. 149
In the first and second of these divisions one boiler only is
employed, but in the last division are included engines with one
boiler and also engines having a double boiler (Fairlie type).
As regards compounding, no engines of the first division have been
so adapted, but the writer is aware of several designs for the
adaptation of compounding to such engines.
In the second class, comprising engines having two sets of coupled
wheels carried under one boiler, one set being carried in a bogie
frame, and each set having an equipment of operating cylinders,
compounding is now well-nigh universal, for as four cylinders are a
necessity if the engine is to be really powerful and large, it becomes a
matter of difficulty to supply high-pressure steam to all of them, and
compounding is almost a sine qua non. Indeed, useful though such
engines have proved themselves for the adoption of this design of
articulated engine constitutes the simplest means of providing
adequate power on light, heavily-graded, and curved lines and
although many such non-compound engines have been employed for
the last forty years or more, it is only since the application of com-
pounding thereto that engines of this type have been introduced in
large numbers as a really satisfactory class.
The Mallet System. This system is by far the most generally
employed for these engines. In fact, so extensively is it used that
by many people the general type is referred to as the Mallet type,
whereas the type is really the Meyer type (introduced in 1867),
adapted for compounding by Monsieur Mallet since about 1 884. It
should, therefore, more correctly be referred to as the Meyer-Mallet
design, in the same way that the Meyer-Lindner system (described
later) is always referred to.
In the Mallet system the high-pressure cylinders are carried by the
frame and drive four.- or six-coupled wheels at the back part of the
engine in the usual way, and the low-pressure cylinders are fitted
upon a large pivoted truck and actuate a second set of four- or six-
coupled wheels at the front of the engine.
The low-pressure cylinders are always fitted at the front of the
engine because the pressure of the steam to be supplied is lower
than that for the high-pressure cylinders, and steam-tight joints can
therefore be more readily effected for the telescopic and movable
connecting steam pipe that is required, and the exhaust is required
to pass to the chimney.
On the Continent these engines are often referred to as duplex
compound engines ; but they are very correctly described as " engines
having an articulated forward motor truck."
Monsieur Mallet's designs for these engines were first prepared
about 1876-7, these designs being included in Chapter IV., but it
was not until 1887 that it was introduced into practice for service
011 the Decauville Railroad (25 in. gauge), to enable the weight
of the engine to be brought to nearly 12 tons, and to enable it to
pass around curves of 15 to 20 metres radius. The weight of the rail
led to the use of four drivers, and the shortness of the radius of the
150
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
curves was inconsistent with
gauge lines; and, as already
the coupling of four axles in the
ordinary way.
Mallet Compound Engines for
St Gothard Railway. Fig. 127
is an interesting drawing show-
ing the first engine "L'Avenir"
in outline, compared with the
largest engines of the class (for
the St Gothard Railway of
Switzerland) in Europe. The
frame of the engine, as may be
seen, is divided in two parts,
united by an articulation in the
form of a vertical hinge. The
rear part is fixed to the boiler,
and the fore part of the latter
rests on the front frame by
means of a curved guide, which
allows the angular displacement
of the fore part relatively to
the rear part on curves. The
cylinders at the rear are high-
pressure ; the pipe-work that
leads the steam from the boiler
to them is fixed in the same
manner as in ordinary loco-
motives ; the two groups of
cylinders are united by a longi-
tudinal tube acting as a receiver,
a vertical elbow pipe fitting in
a stuffing box being fitted near
the hinge connecting the two
frames. This articulated con-
nection is the only one besides
that of the exhaust pipe to the
chimney, and, as has already
been said, it has to resist com-
paratively low pressures only.
The transmission of motion for
the reversing gear, the brakes,,
etc., is effected by means of
jointed rods of no serious com-
plication.
Although intended primarily
for light narrow-gauge lines, the
Mallet-Meyer design has been
used quite as much for large
engines working on standard-
mentioned, the largest engines in
ARTICULATED COMPOUND ENGINES. 151
Europe, for the St Gothard Railway, are of the same class. These
were built by the firm of J. A. Maffei of Munich in 1889, and are,
as will be seen from fig. 127, large tank engines, having two sets
of six-coupled wheels.
The following notes concerning this engine will be of interest :
The engine weighs 83 tons in working order. The reasons which
led to the construction of this type are to be found, not so much in
the desire to possess a more powerful machine than the ordinary
ones with eight-coupled wheels in operation on the Gothard, but to
get additional safety in traffic on Alpine lines.
The ordinary engine weighs 52 tons, and has a separate tender of
27 tons when laden, In constructing the new machine the following
objects were kept in view :
1. To haul the same trains by the same total motor weight
without increasing the strain on the rails, and under more favourable
conditions as to the adhesion, so as to have a guarantee against
difficulty in the tunnels, which are so numerous on this line, or from
bad weather.
2. To haul heavier loads under good climatic conditions.
3. To obtain a far greater speed with like loads.
4. To offer less resistance on curves of 300 metres radius.
5. To effect a saving of fuel in hauling equal loads.
How important this last requirement is will be easily understood
when it is borne in mind that the engines consume over 30 kilos
of fuel, which costs 33 francs per ton delivered on the spot per
kilometre.
The new engine realised all the conditions, and in over two years
of service not the least inconvenience occurred to counterbalance
the advantages which have been obtained.
Before being sent to Switzerland, the engine was subjected to
trials on the line of the State of Bavaria ; and between Mtinchen and
Schliersee, over gradients of 16 per 1000, it hauled a train of forty-
three freight-cars, weighing 400 tons, at a speed of 20 kilometres per
hour. On the St Gothard lines, in fair weather, it hauls 200 tons,
while the ordinary engines haul only 175 tons.
At starting, boiler steam is admitted to the high-pressure cylinders
only ; the exhaust steam from these cylinders then fills the receiver,
exercising a certain amount of back pressure upon the high-pressure
pistons as it passes to the low-pressure cylinders. The steam
pressure in the receiver is limited to 70 pounds per square inch, safety
valves being provided to prevent the accumulation of a higher
receiver pressure. The receiver acts somewhat as a pressure
regulator between the two cylinders, so that if the front engine
should slip there is a corresponding decrease of pressure in the
receiver, while in the case of the rear engine slipping the reverse
would take place. In both cases either engine will cease slipping
without the regulator being touched. If necessary, the starting of
the locomotive can be assisted at certain positions of the high-
pressure pistons by admitting live boiler steam to the receiver, and
152 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
this can be done automatically by connecting the auxiliary steam
cock with the reversing gear.
As a rule, these locomotives are built as tank engines with all
wheels available for driving, but sometimes a separate tender is
employed, and many notable tender engines of this type, some with
a leading pair of carrying wheels, are in use.
Mallet Compound Engines for Russia. Fig. 128 illustrates the
arrangement of steam connections as employed for some large twelve-
wheeled engines for the Moscow-Kasan Railway of Russia. The
chamber a receives the high-pressure exhaust steam from both
cylinders, and to it is connected, by a vertical pivoted pipe b, the
long pipe c, extending to d, where a spherical joint is provided. The
pipe c, which serves the purpose of a receiver, is therefore able to
freely accommodate itself to the pivotal movements of the leading
pivoted frame. At d the steam divides into two pipes, one leading
to each of the low-pressure cylinders. The low-pressure exhaust
steam passes by the pipe e, which has spherical connections at both
ends and a little endways freedom, to the blast pipe.
The low-pressure frame is not strictly a bogie, as it is pivoted at
the rear, and not by a central pin. Its pivot is shown at/.
Such engines as these, together with corresponding eight-wheeled
engines, are extensively employed on Russian railways, including
the Trans-Siberian Railway.
Fig. 129 is a cross section of this engine through the high-pressure
cylinders, and fig. 130 is a similar view showing the steam connec-
tions of the low-pressure cylinders.
The arrangement of steam connections varies, of course, in various
designs, particularly in reference to the flexible connection between
the high- and low-pressure engines. According to one arrangement,
the connecting pipe includes a flexible section, and is connected to
a special receiver chamber, from which the steam is distributed to
the low-pressure cylinders. The exhaust pipe from the low-pressure
cylinders is provided with a telescopic joint instead of a flexible
connection, as in the design illustrated.
The details of starting mechanism also vary according to the
practice of various builders. In one arrangement, to enable boiler
steam to be used in the low-pressure cylinders at starting and when
required, boiler steam passes through a small pipe, governed by a
three-way cock in the cab, and to divert the high-pressure exhaust
to the blast pipe under these conditions a lift valve is fitted so that
the connection from the receiver pipe to the low-pressure cylinders
is closed, and a passage-way opened through a pipe to the blast pipe.
This valve is adapted to be opened through a rod having a closing
spring so that as soon as released the valve closes, and a trip device
is fitted whereby when the reversing lever in the cab is thrown fully
over either way this rod is operated, but as soon as the valve gears
are linked up the valve is released. Consequently the engine can
only be worked non-compound when in full or nearly full forward
or backward gear. This mechanism is very similar to that employed
ARTICULATED COMPOUND ENGINES.
153
&
154
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
by the firm of J. A. Maffei of Munich, and described in Chapter VII.
(figs. 79 and 8u).
Mallet Compound Engines in the United States. Although used
so extensively all over Europe and in many other parts of the world,
engines of this class are not used in Great Britain, and until 1904
FIG. 129. Cross Section through H.P. Cylinders Mallet Articulated
Locomotive.
they were not to be found in American practice ; but in that year
a large engine was built by the American Locomotive Company for
the Baltimore and Ohio Railroad, which is notable as being by far
the largest engine in the world.
Since this engine was built, two or three other similar but smaller
engines have been supplied by the Baldwin Works for service in the
ARTICULATED COMPOUND ENGINES.
155
Philippines, and a large engine has just been supplied by the Baldwin
Works for road service on the Great Northern Railway (U.S.A.).
This latter engine has two sets of six-coupled wheels and a pair of
FIG. 130. Cross Section through L.P. Cylinders Mallet Articulated System.
carrying wheels at each end, though a tender engine. The wheel
arrangement is therefore 2-66-2.
The Meyer-Lindner System. In most respects this system
represents the adaptation of the Lindner system of starting
156 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
mechanism, substantially as described in Chapter VIL, to articulated
engines, but although in most respects comprising similar construc-
tional methods to those employed by Monsieur Mallet, it differs
therefrom as regards the position of the low-pressure cylinders, which
are placed at the rear of the front coupled wheels and close to the
high-pressure cylinders. This arrangement has the advantage that
the steam passage between high- and low-pressure cylinders is very
short ; and as the relative movement of the two sets of coupled wheels
is very limited at this position, being close to the pivoted connection
of the swivelling frame, the joints of the steam pipes can be made
very simple.
Compound Fairlie Engines. Engines having two pivoted bogies,
instead of one fixed frame and one swivelling frame, belong to either
of two classes : (1) having two separate boilers or one double boiler,
and (2) having one ordinary boiler only.
In the first class the engines are of the Fairlie type, but the writer
only knows of two instances of the adaptation of compounding
thereto.
In one case each bogie has a high- and a low-pressure cylinder, so
that it is really a duplex two-cylinder compound engine.
L P. Cyl. Annular Round H.P. Cyl
Duplicate
Engines
'EndloEnd
FIG. 131. Mechanism for Annular Compound Double Locomotive
Johnstone Annular System.
In the other case, of American build, the engine is an eight-
cylinder compound articulated Fairlie type engine. This engine is
really a double Vauclain compound engine with superposed cylinders,
arranged as described in Chapter X.
The Johnstone Articulated Compound Engine. Reference has
been made in Chapter X. to Mr F. W. Johnstone's annular com-
pound system, as applied to more ordinary locomotives. The
system has also been applied for some extraordinary double-
articulated tank engines, intended for mountain goods service over
very sharp curves.
Three of these engines were built in 1892 by the Rhode Island
Locomotive Works for the Mexican Central Railroad. There are
two sets of six-coupled wheels set in bogie frames, leading and
trailing pony trucks, and two connected boilers set on a rigid frame,
water being carried in saddle tanks over the boilers, and fuel in
bunkers fitted on the frame.
The cylinders are fixed upon the frame, not on the bogies, and
there are eight of them, four upon each part of the engine, there
being a high-pressure cylinder and an annular low-pressure cylinder
ARTICULATED COMPOUND ENGINES.
157
disposed round it at each side
of the engine at each end. Each
low-pressure piston has two piston
rods, and these and the corre-
sponding high-pressure piston rod
are connected to one crosshead.
To connect with the wheels, an
ingenious arrangement of mech-
anism is employed as shown dia-
grammatically in fig. 131. Each
crosshead is pivoted to a lever a,
to the lower end of which one
connecting rod is attached, while
to the upper end a link is pivoted
by which a lever b, with a fulcrum
at c on the frame, is driven, the
other connecting rod being driven
by the lever b. Thus the wheels
are driven by double connecting
rods, acting at angles of 180,
and the bogie wheels are driven
on curves, whatever the relative
positions of wheels and cylinders.
By this arrangement an equable
turning effect is obtained, and
also any tendency for the bogie to
twist upon its centre is counter-
acted.
In work, these engines are said
to have given very good results,
but no more of them have been
built, nor have any locomotives
compounded upon the Johnstone
system been built for any rail-
ways other than the inventor's
own line.
The Du Bousquet Articulated
System. In 1905 two very
strange articulated engines were
built to the designs of Monsieur
du Bousquet for dealing with the
heavy coal traffic on some sec-
tions of the Northern Railway of
France, one of these engines being
exhibited at the Liege Exhibition.
Fig. 132 is a line drawing which
sets forth the main features of
the design. As will be seen, the
engine, though having only one
158 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
boiler, is mounted on two pivoted bogie frames, each having
six-coupled wheels and a pair of small wheels arranged towards the
middle of the engine, and each having a pair of operating cylinders,
in one case (the rear) using boiler steam, and in the other case using
low-pressure steam supplied from the high-pressure cylinders.
The weak point of the design appears to be the multiplicity of
flexible steam-pipe joints required, some of them for steam at full
boiler pressure (225 pounds per square inch), but special provision
has been made for this, and it is stated that no difficulty has been
experienced from this cause.
The starting arrangements employed correspond very closely to
those employed by Monsieur du Bousquet for the tandem compound
tank engines described in Chapter IX., and according to the de
Glehn system (Chapter XII.), so that extended reference is not
necessary.
CHAPTER XIV.
TRIPLE - EXPANSION LOCOMOTIVES COMPOUND RACK
RAILWAY LOCOMOTIVES CONCLUDING REMARKS
CONCERNING COMPOUND LOCOMOTIVES.
CONTENTS : Mallet's Triple-expansion Engine Riekie's Triple- expansion Scheme
Compound Rack Locomotives with Four and Six Cylinders Concluding
Remarks concerning Compound Locomotives The Future of Compounding
for Locomotives.
Mallet's Triple-expansion Locomotives. In marine and stationary
engine practice the triple-expansion engine, not to mention the
quadruple, and even the quintuple engine, is an acknowledged
success ; but in locomotive practice many engineers deny that even
the ordinary two-stage compound engine has really been satisfactorily
produced, notwithstanding the good work done by present-day two-,
three-, and four-cylinder compound locomotives ; and it is only the
amateur inventors who airily speak of triple, quadruple, quintuple,
and even sextuple expansion for locomotives.
Yet, while these schemes, none of which have ever been tried in
practice, are, as a whole, worthless, when an engineer of standing
deals with the question, even although only on paper, it may be
worth while to consider the suggestions, and therefore it is not out
of place here to describe two triple-expansion locomotive designs
suggested, respectively, by M. Mallet and by Mr John Riekie.
In 1886 M. Mallet, writing to the Institution of Mechanical
Engineers in reference to Mr Sandiford's four-cylinder compound
engine already mentioned, outlined a suggested triple-expansion
express locomotive. There were to be four-coupled driving wheels,
7 ft. in diameter, in the usual positions, and a single pair of 7-ft.
wheels in a bogie frame in front with the leading wheels. The
four-coupled wheels were to be driven by an 18-in. high-pressure
cylinder and a 26-in. intermediate cylinder, and the single driving
wheels were to be driven by two 26-in. low-pressure cylinders.
The arrangement is shown in fig. 133.
Riekie's Triple-expansion Scheme. Mr Riekie's triple-expansion
scheme (fig. 134) consisted in using two outside cylinders, one high-
pressure and one intermediate-pressure, and a large inside single-
159
160
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
acting low-pressure cylinder, all three cylinders driving on to one
axle. The practical arrangement of this design depended upon the
special features of the Riekie system, as described in Chapter VIII.
The cylinders were to be 14, 20, and 28 in. in diameter, with a
stroke of 26 in. This design also included a triple boiler and
various other departures from usual practice.
The engine has been referred to and illustrated in some locomotive
books, generally to be depended on, as an actual engine for the
North- Western Railway of Beluchistan (India), but this is not so.
It is purely a design, though an interesting one.
Compound Rack Railway Locomotives. Rack railways are of
two kinds. One is entirely separated from any other railway ; the
other works in connection with adhesion lines, or forms a part thereof,
the same engines working, or being capable of working, on both
sections.
On railways of the first class the locomotives rely wholly upon
the rack, so that no adhesion cylinders are needed, and therefore,
as these engines are comparatively small and draw light loads, two
FIG. 133. Monsieur Mallet's suggested Design
for Triple- expansion Locomotive.
FIG. 134. Mr Reikie's pro-
posed Design for Triple-
expansion Locomotive.
ordinary high-pressure cylinders are sufficient, and compounding
is hardly required. In the second case, four cylinders are often
employed, two for the rack pinions and two for the adhesion wheels,
though it is a fairly usual practice, even with these engines, to use
only the two cylinders and to provide clutches so that either the
rack pinions or the adhesion wheels can be driven at will.
Many of these four-cylinder rack and adhesion locomotives, of
various designs and dimensions, are in service, but very little has
been done as regards compounding for such locomotives.
The principal system employed for these engines is the Vauclain,
already described in Chapter X. On wholly rack lines, such as the
Count Telferer Railway in Italy, the Vauclain cylinders drive the
rack pinions only. In other cases the Vauclain cylinders drive the
rack pinions and can be coupled to the adhesion wheels when
required.
In another design, which affords an example of a six-cylinder
locomotive, there are three cylinders at each side two Vauclain
cylinders for driving the adhesion wheels and a cylinder on top for
driving the rack.
Fig. 135 illustrates in diagram the various arrangements for
Vauclain compound rack locomotives mentioned : (1) operating the
CONCLUDING REMARKS CONCERNING COMPOUND LOCOMOTIVES. 161
rack only; (2) operating both rack and adhesion wheels from the
same cylinders ; and (3) with six cylinders two for the rack pinion
and four for the adhesion wheels.
Since writing the foregoing, a combined rack and adhesion loco-
motive has been introduced by the Swiss Locomotive Works wherein
high-pressure cylinders drive the rack pinion, and low-pressure
cylinders the adhesion wheels, the engine working compound when
both sets are worked simultaneously, as often occurs in- this case,
or either set can be operated independently with boiler steam.
Concluding Remarks concerning Compound Locomotives. We
have now reviewed every compound system of any importance
FIG. 135. Compound Rack Locomotives.
as employed for locomotives, and, with very few omissions, have
indicated nearly every system that has been employed at all, besides
dealing with a few suggestions which have never been carried out ;
and it only remains for the writer to devote a few words to a resume
of his subject, and the future probabilities and possibilities of the
compound locomotive.
The methods of applying compounding for locomotives now em-
ployed for new locomotives are almost entirely arranged with three
or four cylinders ; for the two-cylinder systems, with their unequal
cylinders, and the necessity for comparatively complicated starting
devices to enable the work in the low-pressure cylinder to be equal
ised with that being done in the high-pressure cylinder when working
non-compound, are being superseded very largely by other systems.
At one time the increased complication and greater first cost of
162 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
engines with more than two cylinders were considered good arguments
against the use of three or four cylinders ; but it is now argued with
success that these factors, though important, are more than balanced
by the mechanical advantages as well as the compound advantages
of multi-cylinder compound locomotives. Moreover, with three or
four cylinders available, the possibility of using them all with boiler
steam on occasions goes far to solve the problem of providing very
powerful engines of ordinary dimension, and, if only for this reason,
compounding represents progress. And when the possibility of
achieving advantage by the compound use of the steam at ordinary
times, that is, for the largest proportion of the time the engine is
working, is added to this, it will be seen that it is almost impossible
for the compound locomotive, if properly designed and handled, to
be other than satisfactory.
The future of Compounding for Locomotives. It is therefore
only reasonable to prophesy that the next few years will see a
great extension of the use of compound engines, especially for hard
passenger and goods traffic. In fact, this prophecy is even now in
the early stages of its fulfilment.
It appears very doubtful whether triple-expansion engines will
ever be employed for locomotive purposes, for to attempt to go
beyond two-stage expansion is to invite difficulties owing to the
extreme variableness of the working conditions of locomotive opera-
tion, with very little corresponding advantage.
CHAPTER XV.
THE USE OF SUPEEHEATED STEAM FOR LOCOMOTIVES.
CONTENTS : General Remarks The Advantages and Economy of Superheating
for Locomotives A short History of the Schmidt Superheater as applied to
Locomotives The Schmidt Smokebox Superheater, Smokebox Type The
Schmidt Superheater, Smoketube Type Schmidt Superheaters in Belgium
The Pielock Superheater The Cole Superheater Superheating Apparatus
on the Lancashire and Yorkshire Railway The Cockerill Superheater The
New Century Engine Company's System Superheating Apparatus in New
Zealand.
General Remarks. The principal reasons for the employment of
superheated steam in steam engines have already been set forth in
Chapter I., so that it is unnecessary to do more than summarise the
remarks there made as introduction to this chapter. The reasons
are (1) to provide "dry" steam at a higher temperature than that
corresponding to its pressure, and thus to minimise cylinder cooling
and cylinder condensation, and enable extended expansive working
to be employed ; (2) to increase the volume of the boiler steam before
it is used in the cylinders ; and (3) to utilise some of the heat re-
maining in the furnace gases after they have passed through the
boiler tubes, and before they are passed away up the chimney.
The Advantages and Economy of Superheating for Loco-
motives. In the case of locomotive engines these advantages exist
to nearly the same extent as they do in the case of stationary and
marine engines ; for whereas compounding as applied to locomotives
requires to be considered on a special basis, superheating is only
differentiated in detail matters, such as the fact that most super-
heating apparatus for locomotives necessitate some diminution of
the steam generative efficiency of the boiler (usually only slight,
however), and that a special construction of slide valves, especially
when of the piston type, is usually necessary owing to difficulties
attending the use of high-temperature dry steam and the consequent
loss of the lubricating capabilities of " saturated " or ordinary wet
steam.
The principal problem attending the adaptation of superheating
apparatus for locomotives has therefore consisted in the design and
construction of the apparatus in such a way that it can be con-
163
164 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
veniently applied without detracting from the steam generative
efficiency of the boiler, and without interfering with tube cleaning
and repairing, though a few other minor difficulties, such as those
mentioned relating to the construction of slide valves, have also
required consideration before superheating for locomotives could be
said to be really satisfactory.
In nearly every case the superheating apparatus employed is
arranged in the smokebox, which is made somewhat larger than it
would otherwise be, and tubes extend into the boiler tubes (some of
these are usually larger than the ordinary tubes), the arrangement
being such that the whole apparatus can be easily withdrawn when
necessary. In one or two instances, however, the superheating
chamber is fitted within the boiler itself.
A short History of the Schmidt Superheater as applied to
Locomotives. Some half-dozen types of superheating apparatus are
now in use for locomotives, but the constructions most generally
employed are those designed by Herr Wilhelm Schmidt, a well-
known German engineer, principally associated with stationary
engines and boilers, but who is responsible for the first successful
design of superheating apparatus for locomotives. A number of
constructions of superheating apparatus have, however, been
patented before this, some of which would probably be satisfactory
in use. As a result of the original work of Herr Schmidt, the last
few years have seen experimental work either with the Schmidt
or with other forms of apparatus, some of which are practically
adaptations of the Schmidt superheater, on railways of nearly
every country in the world.
The following is a brief history of the Schmidt superheating
apparatus, which will fittingly introduce a technical description of
the two constructions in use.
The first engines were built for the Prussian State Railways in
1898, so that it will be gathered that superheating for locomotives
is quite a recent development of locomotive engineering; and the
original application was largely due to Herr Miiller, of the Prussian
Ministry of Public Works, and to Herr Garbe, Member of the Berlin
Board of Directors, who recognised the value of Herr Schmidt's work,
and at once afforded him every facility for carrying out his object.
Indeed. Mr Garbe, together with the Vulcan Engineering Company
of Stettin-Bredow, Mr A. Borsig of Tegel-Berlin, Messrs Henschel &
Son of Cassel, the Hohenzollern Locomotive Works of Dlisseldorf,
and the Union Foundry of Konigsberg, are deserving of special credit
for the part taken by them in introducing the Schmidt system into
the Prussian State Railway service, and in adapting the apparatus
to the requirements of locomotive practice.
Credit is also due to the following gentlemen : Mr George Noltein,
of the Moscow-Kasan Railway Company ; Mr E. A. Williams, formerly
Superintendent of Rolling Stock of the Canadian Pacific Railway ;
Mr Ren<$ Bertrand and Mr B. Flamme, of the Belgian State Railways.
As early as the year 1900, both Mr Noltein and Mr Williams had
THE USE OF SUPEKHEATED STEAM FOR LOCOMOTIVES. 165
trial locomotives built on the Schmidt superheated steam system for
their respective railways, while in the year 1901 the Directors of the
Belgian State Railways, at the instance of Messrs Bertrand and
Flamme, were the first to adopt the "smoketube" superheater
described later.
The first two superheater locomotives on the Prussian State Rail-
ways were put to work in the beginning of the year 1898, and, it
may be added, are still in regular express service. Although a
number of obstacles were naturally encountered in the construction
of these particular engines, in so far as concerned the adaptation to
the somewhat complex conditions of railway operation of so essentially
new a feature as highly superheated steam, Mr Schmidt soon over-
came these difficulties by improving the details of the apparatus, and
by designing special forms of pistons, piston valves, and stuffing
boxes, which were thoroughly suited to withstand the high tempera-
ture, and which therefore ensured great efficiency and durability.
In 1899 the two original locomotives mentioned above were
followed by two further superheated steam express engines, and in
1900 by two superheater passenger tank engines. These six trial
engines proved conclusively that it was possible, notwithstanding the
unfavourable conditions under which locomotives usually work, to
generate and successfully employ highly superheated steam in such
engines, the practicability of which had previously been doubted,
even by leading engineers. The Administration of the Prussian
State Railways have since applied the Schmidt apparatus to an
increasingly greater extent year by year, as the following figures
testify :
in 1902, 24 engines were fitted with his superheating apparatus;
in 1903, 40 engines
while 123 additional superheater locomotives were ordered in 1904
(57 engines in July and 66 engines in November).
In addition to these engines, the Schmidt apparatus has been
fitted to locomotives of many other countries, as the following
particulars, compiled from additional information recently supplied
to the writer by Mr Schmidt, will testify.
The apparatus is now employed for engines of various types to
locomotives of the following railways, besides the Prussian State
lines :
Imperial Railways of Alsace-Lorraine.
Canadian Pacific Railway (a large number of engines).
Moscow-Kasan Railway.
Belgian State Railways.
Cape Government Railways.
Swedish State Railways.
Saxon State Railways.
Swiss Government Railways.
Austrian State Railways.
Hungarian State Railways.
166 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
Warsaw-Vienna Railway.
Paris-Orleans Railway.
Paris, Lyons, and Mediterranean Railway.
Western Railway of France.
Great Western Railway of England (one engine).
Besides these, there are a few other instances of one or more engines
being so fitted, making a total, according to the particulars in the
writer's possession, of 287 engines.
Since this list was made up a number of other engines have been
fitted with the Schmidt apparatus, notably, additional ones in
Belgium, Canada, and some in the United States, and the actual
number is now probably between 400 and 500.
The Schmidt Superheater, Smokebox Type. This system of
superheating is based on the following principle : The gases of
combustion issuing from the firebox are divided into two separate
currents ; one, the larger current, passes through the ordinary tubes
in the boiler and generates steam in the usual mariner, while the
other and smaller current flows through a single large flue or tube
which extends from the firebox and along the lower part of the boiler
barrel to the superheater apparatus in the smokebox. The gases in
this flue are cooled only to a comparatively small extent by the
water, and the heat is consequently utilised for superheating purposes.
Therefore, as the temperature of the gases entering the apparatus is
comparatively high, a relatively small amount of heating surface,
easily provided and accommodated, suffices to highly superheat the
steam before it reaches the valve chests. Approximately, 10 per
cent, of the heat developed on the grate is employed in this way.
The heating surface of the boiler is but inappreciably diminished.
On the other hand, the total cross-sectional tube area is increased a
fact of great importance when hard work has to be done while the
superheater sensibly increases the total heating surface, and thus
secures a better use of the gases of combustion than would otherwise
be possible. As a matter of fact, the efficiency and draught of the
boiler are improved by the increased cross section of free passage for
the gases, since the vacuum in the firebox will be greater, and more
coal can therefore be burnt per hour than in an ordinary locomotive.
Referring to fig. 136, it will be seen that the large flue tube in the
lower portion of the boiler conducts the hot gases from the firebox
direct to the superheater, and that the latter consists of a number of
small tubes arranged in three concentric rows and situated in the
annular space of the extended smokebox. The inner row is so bent
as to constitute an arched continuation of the flame tube. This arch,
which has a gradually decreasing radius towards the front of the
smokebox, thus forms a passage, which conduces to a uniform distri-
bution of the gases in the superheater. The superheater tubes arc
expanded into the walls of two cast-steel headers or steam chambers,
which are fixed in a longitudinal position inside the roof of the smoke-
box, one on each side of the chimney, and are covered on the outside
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 167
by detachable steel casings, packed with asbestos, and secured by
screws. The space occupied by the superheater is separated from
the remainder of the smokebox by a wall of removable plates which
168 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
extends almost up to the headers, and is shaped to the form of the
superheater tubes, which, in turn, follow the contour of the smoke-
box interiorly. This wall is effectually protected from the destructive
action of the high temperature of the gases in the superheater by the
rows of tubes located before it, and from the abrading action of cinders
in the smokebox by guardplates, which are capable of being easily and
inexpensively changed. Between each header and the top of the
wall on either side a long narrow opening is left through which the
superheater gases pass on their way to the chimney, and each of
these openings is covered by a damper operated from the footplate.
For the purpose of collecting the cinders which fall between the
superheater tubes, a hopper, which can be emptied on the completion
of a journey, is fitted below the apparatus. During the run, soot
and ashes can be removed from the superheater coils by means of
either superheated steam or compressed air, the device for effecting
this operation being controlled from the cab. In order to facilitate
thorough inspection and cleaning, the inner casing of the apparatus
can be taken down if desired, but experience proves that this course
is seldom necessary,
With a view to avoiding loss of heat by radiation, the superheater
is provided with plates arranged just inside the wall of the smoke-
box, while it is further protected by asbestos sheeting, covered by
plates, on the outside of the smokebox.
The hot gases enter the arched distributing channel, and ascend
between the superheater tubes on each side of the apparatus. When
the engine is at work, or when the steam blower is closed while the
engine is standing, the superheater dampers are open, and the gases
are then discharged into the smokebox, where they combine with
those issuing from the boiler tubes, and finally escape into the atmo-
sphere via the chimney.
Owing to the fact that the combustion in the firebox of a locomotive
is only intense when the regulator is open, and when, therefore, the
escaping steam produces a vacuum in the smokebox, the superheater
possesses a very wide margin of safety and durability. When, for
instance, the regulator is open, the superheater tubes are cooled by
the inflowing steam ; and when, on the other hand, it is closed, the
gases of combustion enter the superheater at a low velocity and at a
low temperature, so that the uncooled superheater coils cannot in
any case become distorted. It is unnecessary, therefore, that the
superheater dampers should be shut while the engine is standing,
unless the steam blower is in use. For this reason, the rod control-
ling these dampers is so connected with the lever of the steam blower
that when the latter is employed the dampers are closed.
The action of the superheater is as follows: On the regulator
being opened, steam flows direct from the main steam pipe to the
left-hand header, and then passes through the inner row of super-
heater tubes to the right-hand header. In this header a baffleplate
or cover is fitted over the ends of the inner and middle rows of tubes,
by means of which the steam, on leaving the former, is diverted into
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 169
the central rings, and returns through them to the left-hand header.
This header also contains a baffleplate, fixed, in this case, over the
openings of the middle and outer series of tubes, and so arranged
that the steam is conducted from the central rings of tubes into the
outermost sets, and thus finally flows back to the right-hand header,
from which it passes in a highly superheated condition to the valve
chests and cylinders. In this way the steam is made to traverse
the superheater three times from left- to right-hand header, and
vice versa, and from left to right again before reaching the -cylinders.
As the combustion gases, both on entering and leaving the super-
heater, come in contact with tubes whose surfaces are cooled by wet
steam, their temperature is sufficiently reduced to prevent the tubes
which contain superheated steam, and which are therefore much
hotter than the others, from becoming overheated. Thus the high
temperature of the gases cannot act injuriously on the walls of the
superheater tubes.
As already stated, the headers are provided with detachable covers.
These covers in reality form part of the outside of the smokebox, and
afford direct communication with the interior of the headers. They
can be readily removed for the purpose of expanding or plugging the
tube ends when necessary. Since, by reason of their bent form,
the tubes can expand freely, and since their extremities lie at the
top of the superheater, and consequently only come in contact with
gases having a temperature varying approximately from a minimum
of 570 F. to a maximum of 750 F., loosening of the joints is a very
remote contingency. If, however, any of the tubes should get loose
in course of time, the difficulty can be temporarily and easily over-
come by plugging those tubes, without necessitating the withdrawal
of the engine from service. If a considerable number of tubes
become so defective as to require renewing, the upper part of the
smokebox, together with the complete superheater, can be removed,
so that the whole apparatus is capable of being readily examined and
repaired.
In a general way, regulation of the superheating by means of the
dampers is wholly unnecessary, but their provision enables the
driver to reduce, or to entirely stop, superheating, as the case may
be, when special circumstances render either course advisable. As a
rule, therefore, the driver does not have to pay any attention
whatever to the superheater whilst running, so that he can devote
his time entirely to his usual duties. A steel mercury pyrometer is
fixed in the cab for the purpose of indicating to the driver the
degree of superheating. Although this pyrometer gauge is not
absolutely essential, it is extremly desirable and useful. For test
runs it is indispensable. It is also of great value to the driver,
inasmuch as it enables him to control the combustion and evaporation
in the boiler, while a slagged grate, holes in the fire, or priming of
the boiler, frequently caused by the water-level being too high, or
by dirty, scummy water, are conditions which, owing to their effect
on the degree of superheating, are at once made known by means of
170 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
this instrument. Priming of the boiler is indicated by a rapid fall
in temperature; the driver can then, by promptly throttling by
means of the regulator, prevent, or at all events diminish, this
trouble. Consequently, all German superheated steam locomotives
have so far been fitted with a pyrometer.
A special advantage of this type of superheater is, that as the
smokebox tubeplate is always accessible, the boiler tubes can be
either cleaned or renewed in the ordinary manner without difficulty.
The Schmidt Superheater, Smoketube type. In this system, as
shown by fig. 137, the upper part of the boiler barrel is fitted with
two or three rows of large fire tubes or flues, which are expanded
into the firebox and smokebox tubeplates. These flues are 4| in.
in diameter, except at the extreme firebox end, where they are
contracted to a diameter of 3J in. Inserted in each flue are four
weldless steel superheating tubes, the front ends of which extend
into the smokebox, where they are bent upwards and secured to a
flange common to each set of four tubes. At their other ends,
these steel tubes are united in pairs inside the large flues by means
of cast-steel U-bends. The flanges of the several sets of superheating
tubes are bolted to a common cast-iron header, arranged transversely
inside the smokebox. The header is constructed in such a manner,
and is so connected with the regulator pipe and with the pipe
leading to the valve chests, that the steam is conducted through all
the superheating tubes simultaneously on its way from the boiler
to the cylinders.
A portion of the gases of combustion passes through the ordinary
boiler tubes, while the other portion flows through the large flues,
and its heat is partly given up to the water surrounding flues, and
partly to the steam in the superheating tubes enclosed within
them. The flow of gases through the large flues is controlled by a
damper hinged or pivoted below the header in the smokebox. This
damper is kept closed by a counterweight so long as the regulator is
shut : but immediately on the opening of the regulator, it is auto
matically lowered by means of a piston working in a small steam
cylinder and operating suitable lever gear. Thus, while getting up
steam, or whenever the regulator is closed, and when, therefore, the
superheating tubes are not cooled by the inflow of saturated steam,
no gases of combustion pass through the large flues. The super-
heating tubes are consequently prevented from becoming unduly
heated at any time. Only when the regulator valve is opened is
steam admitted to the small steam cylinder for the purpose of
lowering the damper. As the piston of this cylinder in its end
position acts as a valve, which is kept closed by the steam pressure,
leakages past the piston cannot cause a loss of steam. The piston
can therefore be adjusted to work freely and reliably. If desired,
the superheated damper can be actuated from the footplate by
hand-power instead of by steam ; and as it is only necessary that the
damper should be closed when the steam blower is in action, the
damper lever can with advantage be connected to the lever con-
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 171
trolling the blower, in such a way that the latter can only be turned
on when the damper is shut.
Soot and ashes can be removed from the large flues and super-
172 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
heater tubes by means of either steam or compressed air, with the
aid of a hose and blast pipe. This operation is preferably carried
out from the firebox, but it can also be performed from the smoke-
box. As the cleaning can be effected by steam or compressed air
much more quickly than by brushes, it will be found advantageous
to clean the ordinary boiler tubes in the same manner. With this
superheater, it is unnecessary to provide a special hopper to receive
the cinders.
The total heating surface of the boiler is increased by about 5
per cent, by means of this pattern of superheater, while the cross-
sectional area of free passage for the gases is approximately the
same as when the usual boiler tubes take the place of the large
flues.
The great advantages of the smoketube superheater are its
extreme simplicity and thorough accessibility. Each group of tubes
can be readily inspected, repaired, or renewed without the entire
superheater having to be taken to pieces.
Further, it can be more easily fitted than the smokebox super-
heater to inside-cylinder and compound locomotives ; and as the
dimensions of the boiler and smokebox remain unaltered, this
superheater can be easily fitted to existing engines.
In the case of the first superheated steam locomotives on the
Prussian State Railways, as few alterations as possible were purposely
made in such parts of the engines as the superheated steam came in
contact with. Under these circumstances, it was foreseen that several
changes and improvements would be requisite in the course of time.
Accordingly, Mr Schmidt modified the details where necessary
(designing, among other parts, the special form of piston valves
mentioned), and succeeded in fully meeting the conditions imposed by
superheated steam, so that the working of the engines left nothing
to be desired as regards wear and tear, safety, and general efficiency.
The superheated steam locomotives in their present forms prove
that all difficulties have been successfully overcome, and that the
wear and tear of the valves, piston rings, cylinders, and stuffing boxes
are not greater than in the case of engines using saturated steam.
Even in trial runs, when, instead of the ordinary temperatures ranging
from 570-660 F., the engines worked with a temperature of 720 F.,
no trouble whatever has been experienced.
Schmidt Superheaters in Belgium. In concluding these notes, a
short extract from a recently published report prepared by Monsieur
J. B. Flamme, of the Belgian State Railway Administration, on ex-
perience with superheating apparatus for locomotives, will be of
interest :
" By superheating, the volume of steam is augmented proportion-
ately to the rise of temperature, diminishing, however, its density.
In other words, when the degree of superheat is sufficient to prevent
the loss due to condensation in the cylinders, then the surplus heat
contained in superheated steam is sufficient to reheat the walls of
the cylinders, maintaining the temperature necessary to get rid of
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 173
the condensation and the loss of work during expansion. These
trials have brought to light a valuable property of superheated
steam. It was recognised as a bad conductor of heat, contrary to
that which obtains when steam is in the saturated state.
" These numerous advantages, tested by many trials undertaken by
most competent engineers, are specially valuable to the locomotive
engine. The employment of a practical superheater augments the
power of the boiler, and the utilisation of superheated steam is most
economical. This is well observed in hauling heavy goods "trains on
sections of the line having heavy gradients ; for it is then indispens-
able to reduce to the minimum the consumption of water and steam.
For the suburban trains having frequent stoppages superheat is, again,
highly recommended, because it reduces the condensation necessitated
by the frequent stops. High speed is also favourable to the employ-
ment of higher superheated steam, the great fluidity of which, as
well as its dryness, permit running with early cut-offs, which helps
the boiler just at the time when it is most hard-pressed.
" On the other hand, the passage of saturated steam through the
pipes and steam ports is more difficult, and entails inevitably an
increase of condensation.
" At the same time another important question presented itself :
Was it absolutely necessary to superheat the steam to a tempera-
ture reaching 300 to 350 Cent. 572 to 662 Fahr. ? It is evident
that the more the steam is superheated the more necessary it
becomes to give attention to the oiling of the piston valves and
cylinders and to the construction of the stuffing box. With a view
to getting a clear idea of the actual amount of superheat, some trials
were made with a superheater of small surface installed in the barrel
of one of the locomotives. After several months of experiments, it
has been recognised that the utilisation of steam slightly super-
heated does not offer any appreciable economy of fuel or increase
of power."
The Pielock Superheater. Next to the Schmidt superheater, the
apparatus now to be considered, and which is exploited by the Hanover
Engine Works, is probably the one which has been most extensively
employed, though the Cole superheater, next dealt with, bids fair to
be introduced more extensively in the near future.
This apparatus differs essentially from the Schmidt apparatus in
that the superheater is, as shown in figs. 138, 139, and 140, fitted
into the barrel of the boiler in such a manner that some of the
heating surface of the boiler tubes is used, though it is located
far enough from the firebox to prevent the tubes from becoming
overheated.
According to the position and the dimensions, the superheater can
superheat to every required degree of temperature up to 350 C.
The main part of the Pielock superheater is a box, into the end
walls of which the boiler tubes are fitted. Ordinary tightness is
sufficient, as the pressure inside and outside the superheater is the
same.
174
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
s
I
n
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 175
The superheater box is divided by plates, parallel to the boiler
tubes, into several compartments, so as to get a very long contact of
the steam with the boiler tubes.
The steam passes, under boiler pressure, through the pipes E x and
.-<*:;:
'&:%.
:*
FIG. 139. Pielock Superheater detached.
E 2 into the superheater, and is conducted through the different com-
partments in the direction of the arrows, and goes by the pipe A
into the steam chamber which encloses the regulator head.
A tube passing through the bottom of the superheater and boiler
176 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
is fitted with a drain cock, which is used to ascertain if the super-
heater is watertight.
A thermometer on the dome, which is .connected by a pipe with
the steam chamber of the superheater, and whose scale can be clearly
seen from the footplate, shows the temperature of the superheated
steam.
To fit this simple superheater into its place, the main box is first
put into the boiler, before the front or back tubeplate is brought
into position, and is kept there by suitable means. After the tube-
plates are both in position, the boiler tubes have to be tightened,
first in the back tubeplate, then in the plates of the superheater,
and finally in the front tubeplate.
The tightening of the tubes in the superheater plates has to be
done by a specially constructed mandril. To remove the boiler tubes
FIG. 140. Pielock Superheater detached from Boiler and showing Boiler Tubes.
easily, it is necessary to slightly increase the diameter of the holes,
from the firebox tubeplate to the smokebox tubeplate.
A special fastening of the superheater box is not necessary, because
the box is floated, and the surplus weight is taken by the great
number of tubes.
On locomotives with piston valves a superheating of 350 C.
may be used, but on those with flat slide valves, 280 should
not be exceeded. It may be pointed out that, in using superheated
steam, pipes of wrought-iron or steel, stuffing boxes with metal
packing rings, and oil presses should be used. For oiling purposes,
only mineral oil, which boils at a high temperature, should be used.
The advantages of the Pielock superheater are as follows :
(1) Owing to the simple construction of this superheater, it is
possible to build it, not only into new, but also into old locomotives
without making any changes in the boiler, and without loss of
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 177
draught. The strain on the boiler after putting in the superheater,
and so lessening the heating surface, will not be increased but de-
creased, owing to the effect of the superheater being equal to a
larger water-heating surface than that occupied by the superheater.
(2) This superheater is in some ways more economical than the
smokebox superheaters, because it can be put (within certain limits)
where the heating gases are at the highest temperature, and the
heating power which is not used for superheating will be used for
further heating of the water surrounding the tubes on its way to
the smokebox.
(3) The superheater does not necessitate any alteration to the
locomotive to which it is applied, as it will be built to suit the
boiler.
(4) The superheater is safe for working, as the pressure inside and
out is the same. The strain on the boiler tubes remains the same
with or without the superheater, and overheating of the boiler tubes
is impossible if the superheater is so far from the firebox that the
temperature of the heating gases does not exceed 700 to 800 C.
The steam, which passes round the tubes at high speed, cools them
as effectually as the water which surrounds the tubes, and which has
a slow motion usually.
When the locomotive is at rest, no steam is passing through the
superheater, and the temperature of the heating gases in the tubes is
falling so quickly that it is impossible to overheat the tubes ; the
superheating of the steam is, however, still going on, and on starting
the locomotive there is always superheated steam. If a leakage
should occur, it can be detected not only by the thermometer but
also by the draincock. A small leakage does not do any harm,
because a small quantity of water will be evaporated. A large leak-
age will not affect the working of the locomotive, but only the
working of the superheater.
(5) The superheater requires very little attention, because its
action is very even and no regulation is necessary. The work of the
driver is not increased by the superheater.
The trials already made have been very satisfactory. The saving
in coal was on an average 15 to 18 per cent., and in water about 20
per cent. It may be mentioned, that after opening the regulator
the temperature of the superheated steam increases very quickly,
and can be kept very even with a good fire, and that after closing
the regulator the temperature decreases very slowly (per minute
about 1J C.), so that on starting again there is always superheated
steam.
This system of superheater is in use on several sections of the
Prussian State Railways, and also in Baden, Bavaria, Italy, Hungary,
and Switzerland.
It has been found in practice advisable to provide means for
circulating a little steam in the apparatus when the engine is not
working, and this is effected by a simple arrangement of pipes and
controlling valves.
12
178
LOCOMOTIVE COMPOUNDING AND SUPEKHEATING.
The Cole Superheater. The firm of the American Locomotive
Company and several of the Canadian and American Railways have
been well to the fore in the application of superheating apparatus to
locomotives, a large number of engines having been fitted with the
Schmidt apparatus, but besides this Mr F. J. Cole, lately Motive
Power Superintendent of the New York Central and Hudson River
Railway, but now Chief Engineer of the American Locomotive Com-
pany, has introduced another design of superheater which is now
employed for a large number of engines, in many cases on lines also
employing the Schmidt apparatus.
FIG. 141. Smokebox Arrangement Cole Superheater.
Figs. 141, 142, and 143 illustrate the arrangement first employed
in 1904.
The upper rows of boiler tubes are somewhat larger than the
others, and into them extend two concentric tubes, connected respec-
tively to two chambers formed in a header casting mounted in the
smokebox, the other ends of the outer tubes being closed (as shown
separately in fig. 143), while the inner tubes terminate a short
distance before the end is reached, so that the steam can circulate
from one chamber of the header through the annular space between
the two superheater tubes and return through the inner tube to the
other header chamber, and thence to the cylinders. The superheater
tubes are placed towards the top of the boiler tubes. The ends of
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 179
the outer superheater tubes are closed together and pressed to form
arms which rest on the sides of the boiler tubes for supporting
purposes (see fig. 143).
The smokebox header is built up in sections, as shown in fig. 142,
connected together so that the complete apparatus can be readily
fitted and removed with a minimum of trouble.
In later designs, still larger boiler tubes have been employed for
the upper rows, and four sets of superheater tubes fitted in each, as
shown in fig. 144. In this case a special fitting is employed to
FIG 142. Cole Superheater.
support the free ends, having legs whereby it rests on the sides of the
boiler tubes.
In usual designs for large boilers, there are thirty-two large 5-in.
boiler tubes, each containing four superheater double tubes, so that
the heating surface available for superheating is considerable.
Superheating Apparatus on the Lancashire and Yorkshire
Railway. Two or three years ago several of the express engines of
this railway were fitted with superheating apparatus arranged in a
large smokebox formed by an extension into the barrel of the boiler.
The superheater consists of a large drum, through which pass fire
tubes slightly larger than those of the boiler, and the drum is divided
up internally by diaphragms which cause the steam to pass internally
up and down as it circulates through the apparatus.
180 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES 181
These engines are also fitted with steam jackets to the cylinders,
and in the upper part of the superheater is a coil in which the jacket
steam is superheated.
The whole apparatus is so arranged that it can be bodily removed
with little trouble.
With the exception of these engines, the only other British loco-
motive fitted with superheating apparatus is one recently equipped
with the Schmidt apparatus on the Great Western Railway.
The Cockerill Superheater. In connection with the extensive
trials of superheating apparatus for locomotives carried out in
Belgium already referred to, an experimental construction of
apparatus has been designed by the John Cockerill Company of
Seraing, Belgium, and applied to several engines, some of which
were exhibited at the Liege Exhibition of 1905.
The following description is reproduced directly from Monsieur
Flamme's report already referred to in connection with the Schmidt
superheater.
" It was thought that a superheater placed partly in the barrel of
the boiler offered some real advantages, as being lighter, less
cumbersome, easy to clean and maintain, and its introduction does
not necessitate any important modifications in the smokebox.
Consequently it was this kind of apparatus that the Locomotive
department adopted in a new type of powerful locomotive then
being built in the Cockerill Works at Seraing.
" This apparatus was specially designed to enable trials to be made
as to the advantages or otherwise of combining compounding and
superheating, and it has been applied to a large and notable com-
pound locomotive (described in Chapter XII.) built by the John
Cockerill Company.
" The question to be settled was : Is it more economical to divide
the superheater into two parts in such a manner as to raise the
temperature at the entrance to both the high-pressure and the low-
pressure cylinders, or, on the other hand, to devote the whole power
of the apparatus to superheating the steam before it enters the low-
pressure cylinders'? The Cockerill Company, after numerous
investigations, have just completed a superheater that will enable
them to settle this question.
" This system is being tested on a series of compound engines with
four cylinders and six-coupled wheels with a bogie.
" The apparatus for superheating the steam may be used in two
ways. One may heat the steam near to the entrance to the high-
pressure cylinder, and afterwards near to those of the low-pressure
cylinders, or at the entrance of the low-pressure only. The super-
heater shown in fig. 145 indicates the general arrangement, compris-
ing two series of large flame tubes containing the circulating pipes
intended to superheat the steam. The rdle of the compartments
C and H, placed inside the barrel, and the collectors J and D,
installed in the smokebox, will be dealt with later on in connection
with the explanation of the working of the apparatus. In B there
182
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
is a valve with three pistons intended to divert the steam coming
from the regulator towards the compartment C, or into the tube L,
according as it is required to operate the superheat to high-pressure
and low-pressure, or to low-pressure only. The movements of the
valve B are automatically repeated, owing to the presence in the
tube L of an identically similar valve located within B 1 . The
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 183
destinations of the different pipes is made clear by following the
course of the steam as explained below.
"First case. Superheat at the entrance of high-pressure and low-
pressure. The steam, on leaving the regulator A, makes its way,
after passing B, towards the compartment C ; from there it traverses
the left set of superheater tubes and enters the collector D, whence
it goes to the high-pressure cylinders by passing through the valve
B' and pipe E. The superheated steam, after doing work in the
high-pressure cylinders, goes out by the exhaust pipe F, and traverses
the valve B', after that the pipe G, lodged in the interior of the
barrel to enable it to enter the compartment H. From there the
steam goes into the superheating tubes the right set and arrives
at J, whence it passes by pipes K to the L.P. cylinders.
" Second case. Superheat at the entrance of the low-pressure cylinder .
The valve B is placed by the driver in a position that diverts the
direction of the steam directly from the regulator into the pipe L ;
from there it goes to the high-pressure cylinders after having passed
through the valve B' and the delivery pipes E. On leaving the
high-pressure cylinders, the steam traverses the pipes F, the valve
B', and enters into the collector D. From the front it passes back
through the left set of superheater tubes and arrives at the com-
partment C. From this it passes through the valve B into the
compartment H, and traverses through the right group of superheater
tubes, whence it goes into the collector J, and from there by the
delivery pipes K into the low-pressure. A locomotive of type 19
bis, showing this pattern of superheater, is exhibited in the Liege
Exhibition. Trials are going to be continued with a second identically
similar engine to determine which is the more advantageous mode
of working to adopt for the new superheater. It is manifest that if
the superheat is required at the entrance of the low-pressure cylinders
only, it will be possible to dispense with a certain number of parts
of the superheater, and by that means remedy the obstruction in
the smokebox."
The results of these trials will be watched with great interest by
locomotive engineers in all parts of the world.
The New Century Engine Company's System. As an interesting
corollary to the subject of the use of superheated steam for loco-
motives, a system of working which is now undergoing trial in
Great Britain, and which may become a feature of locomotive
engineering practice, is deserving of brief mention.
Superheating is principally intended for the purpose of preventing
the condensation of moisture from steam as it falls in pressure,
by providing a reserve of heat to make up to some extent for the
inevitable loss of heat as the steam is used, and in the arrangements
already described this is effected by heating the steam in super-
heating apparatus after it leaves the boiler, and before it is used in
the engine cylinders. The system now under notice, however, goes
further than this, and also introduces means of economical working
in other ways.
184
LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
According to the New Century Engine Company's system, air under
pressure is mixed with the steam, both being heated before mixture,
and also to a further extent after mixture. The result is that, as air
is a bad conductor of heat, there is an interchange of heat units
r
FIG. 146. The New Century Engine Company's Steam and Compressed
Air System.
between the heated air and the superheated steam, which has the
effect of not only providing all the advantages attending the use of
superheated steam, but also provides a motive fluid which appears
from practical experience to possess peculiar advantages of its
own.
The air pumps are, in the case of a locomotive, operated from the
FIG. 147. New Century Engine Company's Steam and Compressed
Air System.
engine crossheads ; and although this entails expenditure of work, it
is returned by the working of the air in the cylinders in a large
measure, owing to the expansion of air in the heater, and by the
effect that the heater air has upon the superheated steam.
The heating of the air and the superheating of the steam are
THE USE OF SUPERHEATED STEAM FOR LOCOMOTIVES. 185
obtained by utilising the heat of the escaping furnace gases, which
is otherwise wasted, and absolutely no change in the boiler is required,
so that there is no employment for devices which detract even in
a slight degree from the heating surface of the boiler. It will there-
fore be seen that the advantage occurring from the heating of the
air and steam is obtained without utilising any energy which would
otherwise be available for direct steam generation or utilisation.
The apparatus comprises a special arrangement of heating coils
and chambers in the smokebox, as shown in figs. 146, 147, 148.
The air pumps are adapted to compress the air to a pressure slightly
above that of the boiler steam; and when the steam and air are
heated, the volume of the mix-
ture is considerably increased,
although maintained at an ap-
proximately uniform pressure.
At starting, the engine works,
of course, by steam alone, but as
it continues working the steam
is gradually and partially dis-
placed from the apparatus by
the air supplied at about the
same pressure, and in working
it is found that the relative pro-
portions of air and steam become
adapted very nearly to the vary-
ing requirements of work.
Air is admitted to the heating
device whilst the air pumps are
at work, and steam is admitted
from the boiler to the heating
device only when the pressure
in the latter falls below the nor-
mal pressure due to consumption
of the mixture by the engine.
Thus the supply of air and steam FIG. 148. New Century Engine Coin-
to the heating device is self- ^^ SteKm "^ Compressed Air
regulating, the supply of com-
pressed air depending upon the working of the air pumps, and the
supply of steam upon the rate of consumption of the mixture in
the engine, both supplies automatically stopping when the engine,
and consequently the pumps, are stopped, and automatically recom-
mencing when the engine is restarted. The proportions of this
mixture are usually about one of air to eight of steam.
One of the chief advantages is the more complete prevention of
cylinder condensation without injurious temperature, a temperature
of 500 F. being more than sufficient,, in the case of air and steam,
to produce a high degree of economy under this head, whereas a
temperature of 650 F. to 700 F. is probably required for pure
steam as used in a superheater alone.
186 LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
In the case of excessive pressure in the heater, which may occur
on descending gradients, a relief valve is provided.
The apparatus comprises a system of tubes coiled round the smoke-
box and connecting chambers as shown, divided up so that steam
is superheated in one section, air is heated in another, and the
mixture is then further heated in the final section before it is sent
to the engine cylinders.
This apparatus has so far been adapted to two small contractors'
engines for elaborate tests, which have shown very favourable results,
and it has been fitted for some time to a standard engine belonging
to one of the large British railway companies.
The general system of using air and steam together under pressure
is not a new one, for it forms the subject of many patents, but the
system of working above briefly reviewed appears to possess advan-
tages which may result in its extensive adoption in connection with
locomotive and other steam engines.
Superheating Apparatus in New Zealand. A type of super-
heating apparatus has also been adapted to a compound locomotive
in New Zealand, the apparatus comprising a system of coils of
piping arranged in a large smokebox.
In addition to the foregoing, a number of constructions of super-
heating apparatus for locomotives have been patented, but, so far
as the writer is aware, no others have been actually employed.
INDEX.
Adhesion and rack locomotives, 160.
Adjustability of valve-gears, 26.
Advantages of compounding, 11.
of superheating, 163.
Air and sceam, superheated, 183.
American Locomotive Co. , 45, 106, 143,
154, 178.
Andrade's three-cylinder system, 35.
Annular systems, 22, 120, 156.
Argentine, compounds for, 72.
Arrangement of cranks, 25.
Articulated locomotives, 22, 23, 25, 32,
41, 148.
Asynometric system, 41, 50.
Australia, compound locomotives in, 6,
115.
Austria, compound locomotives in, 6,
41, 87, 124.
superheaters in, 165.
B. & C.D.R., compound locomotives
on, 6.
B. & N.C.R. , compound locomotives
on, 6, 37.
Balanced systems, 19, 25.
Baldwin Works. See Vauclain.
Batchellor system, 45.
Baudry system, 41, 131, 137.
Belgium, compound locomotives in, 6,
131, 133, 146, 164, 172.
superheaters in, 164-6, 172, 181.
Borodine, Russian compounds, 109.
Borries (von), 20, 33, 36, 44, 49, 67.
69, 70, 71, 127.
Borsig, A., locomotives, 131, 136.
Bousquet (du), 21, 40, 102, 111, 131, 157.
Brooks Locomotive Co., 80, 104.
Brunner system, 51, 52.
Canada, compound locomotives in, 6.
superheaters in, 4, 164-6, 178.
Capacities, receiver, 24.
Cape Colony, superheaters in, 165.
China, compound loco, in, 115, 133.
Classification of compound systems,
15.
Cockerill superheater, 181.
Cole system of compounding, 20, 131.
superheater, 178.
Colvin system, 48.
Comparison of locomotive and other
steam engines, 7.
Complication, 13.
Compound use of steam, 1.
locomotives, use of, abroad, 6.
Compounding, objects of, 1.
future of, 163.
Compressed air compound locomotives,
115.
air and steam, superheated, 183.
Condensation, cylinder, 2.
Conditions of locomotive work, 10.
Continuous-expansion system, 29.
Cooke systems, 61, 86.
Cooling, cylinder, 2.
Cranks, arrangement of, 25.
Cut-off ratios, 27.
Cylinder condensation, 2.
cooling, 2.
heating, 2.
ratios, 23.
re- evaporation, 2.
Dawes' proposals, 32.
Dean system, 79.
Deeley, R. M., compounds on M.R., 96.
De Glehn. See Glehn (de).
Denmark, compound locomotives in, 6.
Development of compounding, 28.
Direct economy due to compounding,
12.
Divided and balanced systems, 19.
Division of work by compounding,
1,25.
Double low-pressure cylinder, 36.
Du Bousquet. See Bousquet (du).
Dultz system, 63.
Dunbar tandem system, 40.
187
188
INDEX.
Eastern Railway of France, 53, 138.
Economy, direct and indirect, due to
compounding, 12.
of superheating, 163.
Egypt, compound locos, in, 115, 133.
Eight-cylinder compound locomotives,
156.
Expansion, two-stage versus one stage,
1.
Fairlie type, 23, 32, 149, 156.
Fireman's work, influence of compound-
ing on, 13.
First cost of compounding, 13.
Flamme, Mons., paper on super-
heating, 172.
Four-crank systems, general remarks,
13, 19.
Four-cylinder balanced systems, 19.
two- crank systems, 20.
two-crank systems (other than
tandem), 22.
Four-cylinder systems, general remarks,
13, 16, 19.
France, compound locomotives in, 6,
18, 20-1, 34-5, 40-2, 50, 53, 62,
94-5, 102, 109, 111, 115, 131, 133,
134, 137, 146, 157.
superheater locomotives in, 166.
Future of compounding, 162.
G.C.R., compounds on, 6, 96.
G.E.R., compounds on, 6, 28, 29, 36,
o<7 qo
o/, oo.
G.N.R., compound locomotives on, 6,
20, 136, 145.
G.S.W.R., compound locomotives on,
49.
G.W.R., compound locomotives on,
6, 41, 134, 136.
superheaters on, 181.
Germany, compound locomotives in, 6,
20, 33, 36, 41, 44, 49, 51-2, 63, 67,
69-71, 83-5, 87, 109, 127-8, 131,
136, 147, 149, 150, 155, 165.
superheaters in, 4, 164, 173, 177.
Glehn (de), system, 20, 36, 41, 109,
131, 134, 136, 146.
Golsdorf systems, 20, 41, 87, 124.
Great Britain, compound locomotives
in, 5, 6, 17, 18, 20-1, 23-6, 29, 33,
35-8, 40-1, 44, 49, 67, 71, 92, 94,
96-7, 123, 127, 129, 130, 133-4,
136, 145.
superheaters in, 166, 179, 181, 183.
Heating, cylinder, 2.
Henri system, 41, 131, 137.
Holland, compound locomotives in, 6,
41, 50.
Holt's system, 35.
Hudson's system, 33.
Hughes' system, 130.
Hungary, compound locomotives in, 6,
21, 54, 73, 87, 110, 130.
superheaters in, 165, 177.
India, compound locomotives in, 6,
18, 38, 39, 92, 94, 115, 189.
Indirect economy due to compounding,
12.
Intercepting valves, 27.
Italy, compound locomotives in, 6, 65,
115, 124, 160.
superheating in, 177.
Ivatt systems, 20, 49, 145.
Japan, compound locomotives in, 115.
Johnson, Midland compounds, 96.
Johnstone system, 22, 120, 156.
Joy's proposal, 31.
Kemp tandem system, 31.
Krauss & Co., locomotives built by, 109.
L.N.W.R., compound locomotives on,
6, 18, 20, 23, 24, 25, 26, 38, 92,
94, 123.
L.Y.R., compound locomotives on, 6,
129.
superheaters on, 179.
Landsee asynometric system, 41, 50.
Lapage system, 36, 44, 49, 67, 71, 91.
Lindner system, 22, 25, 41, 83, 84,
149, 155.
M.R., compound locomotives on, 6, 17,
23, 96, 97.
Maffei system, 41, 85, 128, 131, 150.
Mallet systems, 22, 25, 28, 33, 35, 36,
38, 39, 41-2, 51, 91, 109, 149, 150,
152, 154, 159.
Mechanical advantages due to com-
pounding, 11.
Mellin system, 47.
Meyer-Lindner systems, 22, 25, 149,
155.
Meyer-Mallet systems, 22, 25, 149.
Morandiere's proposal, 31, 91.
N.B. R., compound locomotives on, 40.
N.E.R. , compound locomotives on, 6,
36, 38, 96, 127.
Nadal system, 62.
New Century Engine Co.'s system, 183.
New Zealand, compound locomotives in,
6, 115.
superheaters in, 186.
Nicholson-Samuel system, 28, 29.
Nisbet tandem system, 40.
Norway, compound locomotives in, 6,
63.
INDEX.
189
Objects of compounding, 1.
of superheating, 3, 163.
One-stage expansion, 1.
Oscillating cylinders, compounding
with, 33.
Pielock superheater, 173.
Pit kin system, 75.
Pittsburgh system, 48.
Player system, 80, 104
Portugal, compound locomotives in,
6, 131, 133, 136.
Pull, unformity of, 3.
Rack locomotives, compound, 160.
Ratios, cylinder, 23.
Reasons for and against compounding.
9.
Receivers and receiver capacities, 24.
Re-evaporation, cylinder, 2.
Rhode Island systems, 45, 121, 156.
Richmond systems, 47.
Riekie system, 18, 25, 92, 94, 159.
Rogers systems, 33, 53, 80.
Russia, compound locomotives in, 6, 21,
35-6, 43, 63, 87, 109-10, 115, 152.
superheaters in, 164-5.
Salmon proposal, 29, 30.
Samuel-Nicholson system, 28, 29.
Sandiford system, 39.
Saturated steam, 4, 163.
Sauvage system, 41, 95.
Schenectady system, 55, 75.
Schmidt superheater, 164, 166, 170-2.
Six-cylinder compound locomotives,
161.
Smith system, 17, 23, 96, 97, 127.
Sondermann system, 109.
South America, compound locomotives
in, 6, 18, 37, 38, 44, 49, 67, 71,
72, 94.
Spain, compound locos, in, 6,43,131,133.
Starting valves, general remarks, 27.
Struwe proposal, 35.
Superheated steam, use of, 3.
Superheater, Cockerill, 181.
Cole, 178.
Lanes, and Yorks. Railway, 179.
Superheater, New Century Engine
Co. 's, 183.
Pielock, 173.
Schmidt, history of, 164.
,, smoke box- type, 166.
,, smoke tube-type, 170.
Superheating, advantages and economy
of, 163.
objects of, 3.
Sutcliffe proposal, 29.
Sweden, compound locomotives in, 6,
47, 87.
superheaters in, 165.
Switzerland, compound locomotives in,
6, 17, 41, 85, 95, 131, 133, 150, 161.
superheaters in, 165, 177.
Three cylinder systems, general re-
marks, 13, 17, 18.
Thrust, uniformity of, 3.
Triple-expansion compounding, 159.
Two-crank four-cylinder systems,
general remarks, 13, 20.
Two-cylinder systems, general remarks,
12, 16.
Two-cylinder tandem system, 51.
Two-stage expansion, 1.
U.S.A., compound locomotives in, 5, 6,
18, 20-2, 33, 38, 40, 45, 47-8, 53,
55, 58, 61, 75, 77, 79, 80, 86-7, 94,
104-6, 115, 121, 129, 131, 133,
139, 143, 154-6, 160, 165.
superheaters in, 164, 166, 170, 178.
Uniformity of thrust and pull, 3.
Valve gear, number of sets of, 26.
gears, adjustability of, 26.
Vauclain systems, 20, 22, 58, 77, 105,
114, 129, 131, 139, 157, 160.
Vulcan Foundry system, 6, 136.
Webb system, 18, 20, 23, 24, 25, 26,
38, 39, 92, 94, 123.
Weir's system, 32.
Woolf compounds, 102.
Work, conditions of, for locomotives,
10.
WorsdelPs system, 33, 36, 44. 49, 67,
71.
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