LIBRARY
UNIVERSITY OF CALIFORNIA.
Deceived
^Accessions No.* ^ciazs No.
.*9 / fl^J^
COMPOUND LOCOMOTIVES
ARTHUR TANNATT WOODS,
M. M. E. (CORNELL UNIV.')
LATE ASSISTANT ENGINEER UNITED STATES NAVY J PROFESSOR OF MECHANICAL ENGINEERING,
UNIVERSITY OF ILLINOIS, AND PROFESSOR OF DYNAMIC ENGINEERING, WASHINGTON UNI-
VERSITY ; MEMBER OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS;
MEMBER OF THE AMERICAN SOCIETY OF NAVAL ENGINEERS; ASSOCIATE
MEMBER OF THE AMERICAN RAILWAY MASTER MECHANICS
ASSOCIATION, ETC., ETC.
SECOND EDITION, REVISED AND ENLARGED
DAVID LEONARD BARNES, A.M., C. E.
MEMBER OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS; MEMBER OF THE AMERICAN SOCIETY
OF MECHANICAL ENGINEERS; ASSOCIATE MEMBER OF THE AMERICAN RAILWAY
MASTER MECHANICS ASSOCIATION; ASSOCIATE MEMBER OF THE MASTER
CAR BUILDERS ASSOCIATION, ETC., ETC.
CHICAGO
THE RAILWAY AGE AND NORTHWESTERN RAILROADER
1893
COPYRIGHT, 1889,
ARTHUR T. WOODS.
COPYRIGHT, 1893,
HARRIET DEK. WOODS.
STije Hakest'Ue $rea8
R. DONNELLEY & SONS CO., CHICAGO
PREFACE TO FIRST EDITION.
In the preparation of the series of articles which are here
collected in book form, the aim of the author was to combine
the description of the various forms of compound locomotives
which have been actually used, with so much of the theory of
the design of compound engines as would seem to be directly
* - * * \
applicable to locomotive pra'ctice.
An effort has been made to present an unprejudiced
analysis of each type, and to point out such advantages and
disadvantages as are apparently clearly demonstrable, while
carefully avoiding matters of individual preference.
Free use has been made of all available material, and the
authority for data, is in general given in the text. The author
wishes to specially acknowledge his indebtedness to Engineer-
ing, and to Mr. Anatole Mallet, civil engineer, Paris ; Mr. A.
von Borries, locomotive superintendent of the Hanover Rail-
road ; Messrs. Henry and Baudry, of the Paris, Lyons &
Mediterranean Railway, and Mr. G. Du Bousquet, of the
Northern Railway of France, for courteously supplying him
with information concerning their designs.
CHAMPAICN, Illinois, January, 1891.
PREFACE TO SECOND EDITION.
In the preparation of the second edition of this book the
aim has been to add all important developments since
the first edition, and to describe not so much the plans of
various inventors, as to place before the reader the actual
construction and practical value of compound locomotives that
have been built and put into service, and to that end proposed
designs have been omitted.
Extended theoretical discussion has been avoided because
of the 'small practical value of such analysis with the limited
data from actual service that is available at this time.
There has been added further consideration of the more
important functions of compound locomotives, based on
analyses of data and indicator cards which were not available
for the first edition. Especial attention has been given to
the development of such safe conclusions about the use of a
compound system for locomotives as are indicated by the
results of service.
Technical papers have been drawn upon to furnish illus-
trations for the second edition, and as it has been found
impracticable to refer in each case to the publication from
which the illustration was drawn, occasion is now taken to
acknowledge the valuable assistance thus obtained from Amer-
ican and Foreign publications.
^The first ten chapters have been prepared with special
reference to students. Chapters XI. to XX. inclusive, refer
wore particularly to the different types of compound locomo-
VI PREFACE.
tives, and have been arranged for designers of locomotives.
Chapters XXI. to XXIII. inclusive, are intended to place
before the reader an unprejudiced comparison of the different
types, and to indicate why double expansion is expected to
be more economical than single expansion for locomotives.
The Appendix gives further information about the topics
treated in the body of the book, and is intended for the
purpose of illustration and explanation.
Valuable assistance has been given by Mr. E. M. Herr,
formerly Master Mechanic of the Chicago, Milwaukee & St.
Paul Railroad, and Superintendent of the Grant Locomotive
Works.
DAVID LEONARD BARNES.
CHICAGO, September, 1893.
TABLE OF CONTENTS.
CHAPTER I.
ELEMENTARY INDICATOR CARDS.
ARTICLE PAGE
1. Types of Compound Locomotives Commonly Used. 2
2. Receiver Type of Elementary Indicator Cards. 2
3. Non-Receiver Type of Elementary Indicator Card. . . . 4
CHAPTER II.
CLEARANCE, COMPRESSION. AND CONSTRUCTION OF THE EXPANSION
CURVE.
4. Clearance. 9
5. Construction of the Expansion Curve. 10
6. Compression. - - - -'-II
CHAPTER III.
MEAN EFFECTIVE PRESSURE.
7. Formula for Calculating Mean Effective Pressure. - - - 17
8. Difference Between Calculated and Actual Mean Effective Pressure. 1 8
9. Decrease of Mean Effective Pressure as Speed Increases. 19
10. Effect on Draw Bar Pull of Decrease of Mean Effective Pressure as
Speed Increases. 19
11. Increase of Per Cent, of Total Power Consumed by Locomotives and
Tenders which follows a Decrease of Mean Effective Pressure
Due to Speed. 20
CHAPTER IV.
DIFFERENCES BETWEEN ELEMENTARY AND ACTUAL INDICATOR
CARDS.
12. Difference Between Apparent and Actual Cut-off. - 25
13. Difference Between Actual and Elementary Mean Effective Pres-
sures in High-Pressure Cylinder. 26
14. Differences Between Actual and Elementary Mean Effective Pres-
sures in Low- Pressure Cylinder. ------- 29
Vlll TABLE OF CONTENTS.
ARTICLE PAGE
15. Differences Between Actual Work done in Cylinder and the Work
shown by Elementary Indicator Cards. - 31
16. Indicator Cards in Practice. - 32
17. Drop in Pressure During Admission, High-Pressure Cylinder. 33
1 8. Rise in Pressure During Admission, Low-Pressure Cylinder. 33
19. Effect of Speed on Shape of Indicator Cards. - 35
CHAPTER V.
EFFECT OF CHANGING THE POINT OF CUT-OFF — PRESSURE IN
THE RECEIVER.
20. Effect of Changing Cut-off in Elementary Engine. 38
21. Effect of a Change of Cut-off on the Receiver Pressure in an Ele-
mentary Engine. 40
22. Equalization of Work in the High and Low-Pressure Cylinders of a
Receiver Compound. - 42
23. Equalization of Work in the High and Low-Pressure Cylinders of a
Non-Receiver Compound. 43
24. Conclusions About Equalization of Work in High and Low-Pressure
Cylinders. - - 44
25. Pressure in the Receiver. 44
26. Loss Due to Drop of Pressure in Receiver. 47
CHAPTER VI.
COMBINED INDICATOR CARDS AND WEIGHT OF STEAM USED
PER STROKE.
27. Combined Diagram, Receiver Type. - - - 48
28. The Rectangular Hyperbola as a Reference Curve. 49
29. Location of Rectangular Hyperbola for Reference. 51
30. Weight of Steam Used per Stroke. 51
31. Weight of Steam Retained in Cylinder at End of Compression. 52
32. Limitations of Combined Diagrams. - 53
33. Re-Evaporation in Receiver. - 54
34. Condensation in Receiver. - 54
35. What is Shown by Reference Curve on Combined Diagrams. - 55
36. Ideal Combined Diagram. - 55
37. Combined Diagram from Non-Receiver or Woolf Type. - 57
38. Method of Combining Indicator Cards from Non- Receiver Type. 58
39. Losses Shown by Combined Diagram from Non-Receiver Type. 61
40. Correct Area of Combined Diagram, Non-Receiver Type. - 63
41. Reference Curve for Combined Diagram, Non-Receiver Type. 63
42. Weight of Steam per Stroke. 64
43. Other Reference Curves for Combined Diagrams. 65
44. Weight of Steam per Stroke, Various Compound Locomotives. - 6£
TABLE OF CONTENTS. IX
CHAPTER, VII.
TOTAL EXPANSION. RATIO OF CYLINDERS.
ARTICLE
PAGE
45. Total Expansion from Elementary Indicator Cards. - 69
46. Total Expansion from Actual Indicator Cards. 69
47. Ratio of Cylinders, Elementary Formulas for. 72
48. Ratio of Cylinders as Affected by Maximum Width of Locomotive. 72
49. Ratios of Cylinders Commonly Used. 73
50. Ratio of Cylinders as Affecting Equalization of Power in Two-
Cylinder Receiver Compounds. 74
51. Ratio of Cylinders and Equalization of Power in Non-Receiver
Compounds. - '-75
52. Ratio of Cylinder Volumes to the Work to be Done. 76
t
CHAPTER VIII.
RECEIVER CAPACITY, RE-HEATING AND SEQUENCE OF CRANKS.
53. Receiver Capacity. 80
54. Re-Heating and Steam Jackets. - 80
55. Smoke Box Temperatures. 82
56. Sequence of Cranks. - 83
CHAPTER IX.
MAXIMUM STARTING POWER OF LOCOMOTIVES.
57. Starting with Close Coupled Cars and with Free Slack. - 84
58. Starting of Two-Cylinder Receiver Compounds Without an Inde-
pendent Exhaust for the High-Pressure Cylinder. 84
59. Starting of Two-Cylinder Receiver Compounds with Independent
Exhaust for High-Pressure Cylinder. - 85
60. Starting of Four-Cylinder Two-Crank Receiver and Non-Receiver
Compounds. - 85
61. Starting of Four-Cylinder Four-Crank Compounds with Receivers. - 86
62. Starting and Hauling Power of Single Expansion Locomotives. - 86
63. Graphical Representation of Hauling Power. - 87
64. Starting Power with Mallet's System and other Non-Automatic
Starting Gears. 90
65. Starting Power with Worsdell, von Berries and other Automatic
Starting Gears. - 91
66. Starting Power with the Lindner system. -• 94
67. Starting Power of Three-Cylinder Three-Crank Compounds. - 95
68. Variation of Hauling Power with Four-Cylinder Two-Crank Receiver
and Non-Receiver Compounds. 95
X TABLE OF CONTENTS.
CHAPTER X.
CONDENSATION IN CYLINDERS.
ARTICLE PAGE
69. Range of Temperature. - - 97
70. Need of Covering Hot Surfaces to Prevent Radiation. 97
71. Condensation, Leakage of Valves and Re-Evaporation as Determined
from Indicator Cards. - - - 98
72. Examples of Determination of Condensation, Leakage, and Re-
Evaporation from Various Indicator Cards. - - - 102
CHAPTER XL
THE VALVE GEAR ADJUSTMENTS.
73. Mallet's System of Cut-Off Adjustment. - - - 106
74. Chicago, Burlington & Quincy System. 108
75. Heintzelman System. ..... - 109
76. The Rogers Locomotive Works Link Hanger Adjustment. - - m
760. Different Adjustments of Cut-Offs that have been Used for Com-
pound Locomotives. - ••---III
CHAPTER XII.
MAIN VALVES.
77. Lap, Travel, and Size of Ports. - . - 122
78. Piston Valves. ------.... I22
79. Some Effects of Inadequate Valve Motions. - - - 123
80. Effect of Long Valve Travel and Inside Clearance or Negative Lap. 124
81. Conclusions about Main Valve Dimensions. jo
CHAPTER XIII.
STEAM PASSAGES — ACTION OF EXHAUST.
82. Size of Steam Passages and Loss Due to Wire-Drawing. - - 132
83. Effect of Exhaust on Fire and on Back Pressure. - - - 135
CHAPTER XIV.
EFFECT OF HEAVY RECIPROCATING PARTS.
84. Weight of Reciprocating Parts. - - - - - 139
85. Advantage of Large Drivers. I40
86. Counterbalancing of Reciprocating Parts. - - - 140
87. Marine Practice in Counterbalancing. - 140
88. Effect of Decreasing Weight of Reciprocating Parts and Increasing
Diameter of Drivers. - . - 144
89. Distribution of Centrifugal Tendency of Counterbalance over the
Track. - I44
TABLE OF CONTENTS. XI
CHAPTER XV.
DESCRIPTION OF TWO-CYLINDER RECEIVER COMPOUNDS, WITH AUTO-
MATIC INTERCEPTING VALVE STARTING GEARS, AND WITHOUT
SEPARATE EXHAUST FOR HIGH-PRESSURE CYLINDER AT STARTING.
ARTICLE PAGE
90. The von Borries System in 1889. 147
91. The von Borries System as used on the Jura, Berne-Lucerne Railway. 150
92. A Modification of the von Borries System. - 151
93. Recent Changes in the von Borries System. 153
94. The Worsdell System. 153
95. A Modification of the Worsdell System. - 155
96. The Schenectady Locomotive Works (Pitkin) System. 157
97. A Modification of the Schenectady Locomotive Works (Pitkin)
System. 160
98. The Dean System. - 165
99. A Modification of the Dean System. 165
100. The Brooks Locomotive Works (Player) System. 169
10 1. The Rogers Locomotive Works System. - 171
102. The Baldwin Locomotive Works System. 178
CHAPTER XVI.
DESCRIPTION OF TWO-CYLINDER RECEIVER COMPOUNDS, WITH AUTO-
MATIC STARTING GEAR AND WITHOUT SEPARATE EXHAUST FOR
HIGH-PRESSURE CYLINDER AT STARTING, AND WITHOUT INTER-
CEPTING VALVE. THE LINDNER SYSTEM; THE COOKE LOCOMOTIVE
WORKS SYSTEM; THE GOLSDORF (AUSTRIAN) SYSTEM.
103. The Lindner System. 181
104. A Modification of the Lindner System. 184
105. The Lindner System as Used on the Saxon State Railroad; The
Meyer-Lindner Duplex Compound. 185
1 06. The Lindner System on the Chicago, Burlington & Quincy Railroad. 185
107. The Lindner System on the Pennsylvania Railroad. - - - 1 88
108. The Cooke Locomotive Works System. 192
109. The Golsdorf (Austrian) System. - - - 194
CHAPTER XVII.
DESCRIPTION OF TWO-CYLINDER RECEIVER COMPOUNDS, WITH INTER-
CEPTING VALVE, AND WITH SEPARATE EXHAUST FOR HIGH-PRES-
SURE CYLINDER AT STARTING.
1 10. The Mallet System. - 196
in. The Early Form of the Mallet System. 199
112. Preliminary Work of Mallet. - 201
113. Rhode Island Locomotive Works (Batchellor) System. - - 202
Xll . TABLE OF CONTENTS.
ARTICLE PAGE
114. The Richmond Locomotive Works (Mellin) %stem. 205
115. The Pittsburgh Locomotive Works (Colvin) System. - 208
1 1 6. von Berries' Latest System. - 209
CHAPTER XVIII.
DESCRIPTION OF FOUR-CYLINDER NON-RECEIVER COMPOUNDS, "CONTIN-
UOUS" EXPANSION OR WOOLF TYPE, VAUCLAIN AND NON-RECEIVER
• TANDEM TYPES.
117. The Dunbar System. 21 1
118. The Du Bousquet (Woolf) System on the Northern Railway of
France. 211
119. Indicator Cards from the Du Bousquet (Woolf) Compound. 213
120. Baldwin Locomotive Works (Vauclain) System. 215
121. Distribution of Pressure on Pistons. - 228
122. Advantages Claimed for the Baldwin Locomotive Works (Vauclain)
System. - - 232
123. The Johnstone System on the Mexican Central Railway. 233
CHAPTER XIX.
DESCRIPTION OF FOUR-CYLINDER, TWO-CRANK RECEIVER COM-
POUNDS— TANDEM RECEIVER TYPES.
124. Tandem Compounds on the Hungarian State Railway. 235
125. Tandem Compounds on the Southwestern Railways of Russia. 237
126. Indicator Cards from Tandem Compounds on the Southwestern
Railways of Russia. ..... 238
127. The Brooks Tandem System. - . - - 239
CHAPTER XX.
DESCRIPTION OF THREE AND FOUR-CRANK COMPOUNDS.
128. Webb System; Express Locomotives without Parallel Rods. 244
129. Webb System; Freight Locomotives with Parallel Rods. 245
130. Webb System on Pennsylvania Railroad. 245
131. Three-Cylinder System Used on the Northern Railways of France. 246
132. Valve Gear for Three-Cylinder Compound on Northern Railways of
France. - 247
133. Summary of Three and Four-Crank Compounds. 248
134. Miscellaneous Designs of Compounds that have Not been Put in
Service. - - 248
CHAPTER XXI.
SUMMARY ABOUT STARTING GEARS.
135. Automatic Starting Gears with Intercepting Valves. - - - 249
TABLE OF CONTENTS. Xlll
ARTICLE PAGE
136. Automatic Starting Gears Without Intercepting Valves. - 251
137. Non-Automatic Gears With Intercepting Valves and With Separate
Exhausts for the High-Pressure Cylinders. - - - - 251
138. Starting Gears for Four-Cylinder Compounds. .... 252
CHAPTER XXII.
REASONS FOR ECONOMY IN COMPOUND LOCOMOTIVES.
139. Possibilities of Savings. 254
140. Saving by Greater Expansion. 255
141. Saving by Reduction of Condensation. - 256
142. Saving by more Complete Combustion. 256
143. Saving in Fast Express and Passenger Service. 257
144. Saving in Slow Grade Work and in Freight and Suburban Service. 257
145. How Saving is Affected by the Price of Fuel and Rate of Combustion. 258
146. Cost of Repairs. 262
147. Methods of Operating to Gain Economy. - 264
CHAPTER XXIII.
SELECTION OF TYPE AND DETAILS OF DESIGN BEST ADAPTED FOR A
GIVEN SERVICE.
148. Four-Cylinder Four-Crank Types. : 269
149. Three-Cylinder Three-Crank Types. - 270
150. Four-Cylinder Tandem Two-Crank Types. - - 270
151. Four-Cylinder Non-Tandem Two -Crank Types, With and Without
Receivers. - - - - 272
152. Two-Cylinder Two-Crank Receiver Types. 275
153. In General About a Selection of a Suitable Design. - - - 277
APPENDIX.
A. Example of Calculation for Mean Effective Pressure during One
Stroke. 281
B. Example of Calculation for Mean Effective Pressure during Expansion. 281
C. Example of Calculation for Pressure in the Receiver. 281
D. Final Pressure ; Total Expansion. 281
E. Drop in Pressure in Receiver. 282
F. Mean Effective Pressure ; Equivalent in One Cylinder. 282
G. Example of Calculation for Mean Effective Pressure when Clearance
is taken into Account. ...... 283
H. Derivation of Formula for Tractive Force. 283
I.. Some further Discussion of Three-Cylinder, Three-Crank Compounds. 284
XIV TABLE OF CONTENTS.
PAGE
J. Example of Modification of Elementary Indicator Cards to Approxi-
mate to Actual Cards for Non-Receiver Compounds. 292
K. Some Further Discussion of Four-Cylinder Receiver Compounds. 293
L. Diagram of Turning Moments of a Lindner Two-Cylinder Receiver
Compound. 299
M. Some Tests of Compound Locomotives in the United States. (Table
II.) 30i
N. Reported Savings of Compound Locomotives in the United States.
(Table H H.) 302
O. Formulas for Expansion Curve. 303
P. Formula for Inertia of Reciprocating Parts. 303
Q. Comparative Cylinder Capacities of Compound Locomotives.
(Table L.) 305
R. Dimensions of Some of the more Prominent Compound Locomotives
that have been Put into Actual Service, Chiefly in the United States.
(Table C C.) 307
Glossary. 311
Index. - .... 1
COMPOUND LOCOMOTIVES.
CHAPTER I.
ELEMENTARY INDICATOR CARDS.
The elementary theory of steam use in compound
locomotives does not differ from that of other compound
non-condensing engines, but it has been found that some
factors, which are of comparatively small consequence in
marine or stationary work, become of importance in the
locomotive. This arises largely from the wide range of
power required from locomotives, and the practical neces-
sity of keeping the valve gear and operating mechanism as
free from complication as possible. The recent introduction
of higher pressures and greater piston speeds in marine
practice has made some of the working conditions of marine
engines more nearly like the conditions of locomotive use
than they have been heretofore.
The action of steam in expanding in a slow moving,
elementary compound engine is well laid down in text
books, and the elementary indicator cards show in a general
way how steam acts in an engine. This is well understood
by most of those who will be called upon to design the cyl-
inders and valve motion of compound locomotives. Such
elementary analysis is, however, of but little value as a
guide to an understanding of what takes place in a com-
pound locomotive. This results mainly from the high piston
speed which causes excessive wire-drawing and compression
with the valve motions ordinarily used. Such motions are
universally positive and direct, and do not differ materially
2 COMPOUND LOCOMOTIVES.
in action from the well-known Stephenson link, and have,
generally speaking, all of its defects. Although elemen-
tary analysis has a limited application to the compound
locomotive, yet it is, perhaps, best to review the elementary
theory somewhat in order to properly introduce the more
complicated and involved conditions, which actually exist
in a practical engine.
1. Types of Compound Locomotives Commonly
Used. — There are two distinct types of compound engines
that have been commonly used ; one has a large receiver
between the cylinders, into which the h. p. cylinder exhausts,
and from which the 1. p. cylinder takes steam. The other
form has no receiver, so-called, but may have a small space
between the cylinders, consisting of the volume of the
clearances of the cylinders and the volume of the space in
the valve.
The first type of compound is commonly called the
" receiver " type ; the second, without a receiver, is gener-
ally known as the "Woolf" or "continuous expansion"
type, and is only used for locomotives, in which both pistons
are attached to the same crosshead. The Woolf type of
expansion of steam is used in the Vauclain type, built by
the Baldwin Locomotive Works, and the Johnstone type,
used on the Mexican Central Railway.
2. Receiver Type of Elementary Indicator Cards. —
The combined elementary indicator card from a receiver
compound engine has the general form shown by Fig. I when
no account is taken of the clearance spaces, and when it is
assumed that steam is admitted and exhausted exactly at
the beginning and end of the stroke, and no allowance is
made for wire-drawing through the steam ports, for com-
pression, nor for irregularity caused by the angularity of
the connecting rods.
The upper part of the card, a, b, c, d, e,f, a, is from the
h. p. cylinder, and the lower part of the card, e, /, g, h, k, e,
ELEMENTARY INDICATOR CARDS. 3
is from the 1. p. cylinder. The cards are on the same scale
of pressures and have the same length, and are placed with
respect to each other as they would be when the cranks are
placed at right angles. This appears from the fact that
the point e, the admission to the 1. p. cylinder, is placed in
the middle of the card from the h. p. cylinder, or just one-
half a stroke later than the admission point a to the h. p.
cylinder. The h. p. card leads to the right and the 1. p. to
the left, as a matter of convenience in illustration, as will
appear later.
ZERO LINE OF PRESSURE
FIG. i.
Receiver Type of Elementary Indicator Card.
The following is a description of the different lines on
this combined diagram : At a steam is admitted to the
h. p. cylinder with a pressure corresponding to the distance
of a above the atmospheric line. Steam continues to be
admitted at this pressure until the piston has advanced to
the cut-off point, at half-stroke in this case, b. From b to
c steam expands, and at c is exhausted into the receiver.
The fall in pressure from c to d represents the drop of
pressure into the receiver, and is a source of loss in com-
pound engines, 26. The most perfect compounds have no
drop of any magnitude when the h. p. cylinder opens to
the receiver, 36. From d to e the h. p. piston is pushing steam
into the receiver. At e steam is admitted to the 1. p.
4 ' COMPOUND LOCOMOTIVES.
cylinder from the receiver, and from e to /steam is being
pushed into the receiver from the h. p. cylinder, and is
being taken out of the receiver by the 1. p. cylinder.
The drop in pressure from e to /is the fall of pressure
in the receiver, and results from the fact that the 1. p.
cylinder takes more steam out of the receiver from e to /
than is put into it by the h. p. piston during the same time.
At /the h. p. piston ceases to push steam into the receiver,
it being at the end of the stroke. At this point also, for
the purpose of illustration, it has been assumed that the
1. p. valve cuts off the steam from the receiver; therefore,
from/to g steam is expanding in the 1. p. cylinder. The
fall from g to h shows the drop in pressure at the exhaust
of the 1. p. cylinder to the atmosphere. From h to k is the
line of back pressure in the 1. p. cylinder, which is some-
what above the atmospheric line, as shown.
In all practical engines, or nearly all, the cylinders are
double acting, and therefore, in the engine assumed for
Fig. I, there will be an exhaust of steam at the end of each
stroke of the h. p. piston ; hence, when the 1. p. piston has
moved to the point /from e, there will be at /an increase
of pressure in the receiver and in the 1. p. cylinder, due to
the exhaust from the opposite end of the h. p. cylinder,
which will cause in actual work the point /to rise slightly.
This will appear from an examination of an actual indicator
card. See Fig. 14. A different arrangement of the cut-off
from that assumed for Fig. I would cause a somewhat
different shape of combined card, but in general the
description given will answer for all elementary indicator
cards from receiver compounds.
3. Non-Receiver Type of Elementary Indicator
Card. — In locomotive practice, so far, four-cylinder com-
pounds without receivers are so made that the h. p. and 1. p.
pistons move together. This type includes the Du Bousquet
non-receiver tandem, the Vauclain, and the Johnstone,
ELEMENTARY INDICATOR CARDS. 5
of the types that have been put into practical service, and
others that have been suggested but not built. The prob-
lems to be solved, when the pistons move simultaneously
are, in some respects, quite different from those for receiver
engines.
The Woolf, or " continuous expansion " engines, is typ-
ical of this class ; the pistons move simultaneously and
FIG. 2.
Non-Receiver Type of Elementary Indicator Card.
there is no receiver. In the simplest forms of this type, as
applicable to locomotives, the h. p. and 1. p. pistons are
attached to the same crosshead, and the slide valves of
both cylinders are operated by the same link motion. The
peculiarities of the steam distribution in this arrangement
of cylinders can be best examined by means of elementary
indicator cards such as Fig. 2.
Referring to this figure, a, b, d, e, /, g, h, k, a is the
h. p. card, and g, h, /, m, n, q, g is the 1. p. card. In the
h. p. cylinder cut-off takes place at b, and there is expansion
in that cylinder until the exhaust opens at d. There is
6 COMPOUND LOCOMOTIVES.
then a drop in pressure to e as the steam in the h. p. cyl-
inder mingles with that in the passages which connect
the cylinders. From e to f there is further expansion in
the h. p. cylinder and the connecting passages. At / the
1. p. steam valve opens and there is another drop in
pressure to g.
From g to h the cylinders are in communication, and there
is expansion until the 1. p. steam valve closes at h. From
h to k there is compression in the connecting passages and
the h. p. cylinder, and when the h. p. exhaust closes at k
there is further compression in that cylinder. In the 1. p.
cylinder the steam expands from h to /, where release
occurs and the pressure drops to the ordinary back
pressure line.
The fall of pressure in the 1. p. cylinder up to cut-off is
shown by g h. The pressure falls because the amount of
steam pushed into the 1. p. cylinder by the h. p. piston is less
than the volume displaced by the 1. p. piston in the same
time. At the point h the 1. p. cylinder cuts off and com-
munication is closed between the h. p. and 1. p. cylinders ;
hence, from h to a the steam remaining in the h. p. cylin-
der is compressed, for it has no outlet. This is often called
"continuous expansion," as there is no pause of expansion
as in the case of those engines where the steam is passed to
an intermediate receiver after expansion in one cylinder.
The features of this diagram which require special
attention are the losses in pressure at d and /"and the com-
pression in the h. p. cylinder. In order to prevent the
drop at d, either the pressure in the connecting passages,
valves and clearance spaces between the cylinders when the
h. p. exhaust opens must be the same as that at d, or else
the volume of the connecting passages must be practically
nothing. The pressure can possibly be made the same as
at d by adjustments of the 1. p. cut-off, but it is not prac-
ticable on account of the unavoidable complications. The
ELEMENTARY INDICATOR CARDS. 7
only feasible method of reducing this loss to an inapprecia-
ble amount appears to be to make the volume of the
connecting passages very small compared with that of the
h. p. cylinder. The drop in pressure at /can be prevented
or reduced by compressing to the pressure / in the 1. p.
cylinder, or by making the 1. p. clearance very small.
The question of compression in the h. p. cylinder in this
type of engine is even more troublesome than in receiver
engines. In order to avoid compressing to a higher pres-
sure than the initial pressure with the usual forms of valve
gear, it is necessary that the volume of the h. p. clearance
space should be made large, since the pressure at k, where
the compression caused by the exhaust closure begins, is una-
voidably high. This pressure can, of course, be somewhat
reduced by making the volume of the passages connecting
the cylinders large, but, as has been shown, this involves a
considerable drop in pressure at d, 37. See Figs, n, 12
and I 50.
The expedient of giving the h. p. valve inside clearance
may also be employed in connection with a large clearance
space to assist in keeping down the compression. In any
case in which the shifting link motion is used, early cut-
offs are to be avoided, both on account of this compression
and to avoid the wire-drawing which results from a small
port opening. The use of late cut-offs has been advocated
by the builders of this class of engine for the reason just
given, but that involves the wire-drawing of the steam for
all light work by closing the throttle. This leads to loss of
potential of pressure and is not conducive to economy,
especially in compound engines, as has been shown by Pro-
fessor Goss in the Purdue University shop tests. See
Fig. 45. 80, 151.
It is, however, not necessary to resort to very early cut-
offs in order to obtain a sufficiently great expansion, as this
may be secured by using a comparatively large cylinder
8 COMPOUND LOCOMOTIVES.
ratio, but at high speeds the wire-drawing and compression
modifies this greatly, 77-82.
In determining the proportions for the valve gear and
the size of the cylinders advisable for a tandem compound
which is intended to take the place of single expansion
locomotive, the most satisfactory mode of procedure will be
to take actual cards from similar engines for various points
of cut-off, measure the area of these cards, and finally to
adjust these cards for losses or gains, according to any pro-
posed changes in design or method of operation. An exam-
ple of .estimating from elementary indicator cards is given
in Appendix J,
CHAPTER II.
CLEARANCE, COMPRESSION, AND CONSTRUCTION OF THE
EXPANSION CURVE.
4. Clearance. — The volume included between the pis-
ton, when at the end of a stroke, and the valve face at that
end is called the " clearance." It includes the volume of the
steam port, the space 'between the piston and the cylinder
head, and any other spaces that are in communication with
\b
FIG. 3.
Construction of Expansion Curve.
these spaces, such as indicator pipes and cylinder drains.
One of the principal effects of clearance is to make the
effective or actual cut-off later than the apparent ; that is,
the cut-off shown by the indicator card is but the " apparent "
cut-off, while the "actual" cut-off is a longer one, as shown
on Fig. 3, as follows :
Let e d represent the stroke of a piston, and assume a
cut-off at one-half stroke and ten per cent, clearance. Then
a b is one-half of e d, and the apparent ratio of expansion
IO COMPOUND LOCOMOTIVES.
is 2. Lay off e f equal to one-tenth of e d, then / e or
a g represents the clearance. The volume which is filled
with steam when cut-off takes place is g b, and this expands
until it fills the volume of f d. The actual ratio of expan-
sion is therefore /W divided by^- d, or as drawn in Fig. 3 it is :
— =—= 1.83 instead of 2. Expressing this as
a formula, the actual ratio of expansion is
n+k
in which k is the clearance expressed as a decimal of the
volume displaced by the piston in one stroke, and n is the
apparent cut-off, or one divided by the apparent ratio of
expansion. The point c on the expansion curve is, of
course, higher with a ratio of expansion of 1.83 than with
a ratio of 2, and hence the mean pressure between b and c
is higher. In making calculations the actual ratio of expan-
sion should of course be used, but the formula, 7, will
not then give correct results, as by it the mean pressure
between ^and c is found, and not that between a and c, and
a correction must therefore be made which necessitates
additional calculation. It is better in most cases to make
use of a graphical construction. For example, see Appen-
dix G.
5. Construction of the Expansion Curve. — A simple
method of plotting points on the hyperbolic expansion curve
is the following, which requires only a triangle and a straight
edge : In Fig. 3 let 0 V be the zero line of pressures, 0 P the
zero line of volumes, and p a known point on the hyperbola.
Through p draw / s parallel to 0 V, making it of any con-
venient length. Draw/ k and s t perpendicular to O J^and
draw 0 s. Through the point u where 0 s crosses/ k, draw
u q parallel to 0 V, and where this line cuts s t at q is a
second point on the curve. Any number of other points
can be found from p or q in a similar manner, as indicated
CLEARANCE, COMPRESSION, EXPANSION. I I
in Fig. 3. An advantage of this method is that the dis-
tance of a point from 0 P can be selected at pleasure, as it
will be always directly under the point to which the diag-
onal is drawn, as q and s, or x and w, 41, 43.
6. Compression. — Compression or cushioning in com-
pound locomotives is a factor of steam distribution which
it is more difficult to* dispose of satisfactorily than in single
expansion engines. For economy of steam, the pressure in
the clearance space, when the steam valve opens, should
not be far from, but somewhat less than, the initial pressure,
while the necessary pressure for "cushioning" the recipro-
cating parts is a problem in itself, and is generally regulated
by the lead of the valves.
In a single expansion engine having an initial pressure
of 175 pounds absolute, and a back pressure of 18 pounds
absolute, it is possible to compress to 9.7 times the back
pressure before the initial pressure will be exceeded. But
in a compound, if the receiver pressure is 70 pounds abso-
lute, the possible range of compression is for the h. p. cyl-
inder from 70 to 175 pounds, and for the 1. p. cylinder from
1 8 to 70 pounds, or 2.5 times in the former, and about 3.9
times in the latter. It will be at once apparent that the
valve adjustment for compression in the compound is a
much more difficult problem than in the single expansion
engine.
For example, with 5 per cent, clearance in a compound
and the pressures as just stated, the pressure in the clear-
ance space at the end of the stroke would equal the initial
pressure in the h. p. cylinder when the exhaust closed at
2.5 X. 05 — .05 = . 075 of the stroke from the end, or at 92.5
per cent, of the stroke, as it is frequently stated. In the
1. p. cylinder, an exhaust closure at 85.5 per cent, would fill
the clearance space with steam at receiver pressure. With
10 per cent, clearance, and the same pressures as before,
the earliest allowable points of exhaust closure would be 85
12
COMPOUND LOCOMOTIVES.
per cent, in the h. p. and 71 per cent, in the 1. p. cylinder.
It is practically impossible to get such late -exhaust closures
at early cut-offs with a link motion, 73-81.
It will be seen from this that a large percentage of
clearance in a compound engine will reduce compression
750
50
%T
•25 ,50 .75
Volume in Cubic jeet
FIG. 4.
Actual Curve of Compression.
and may be a positive advantage, so far as the distribution
of power between the cylinders is concerned, also large
clearance spaces assist in the reduction of high compres-
sion at fast speeds.
An approximation to the relations between the back
CLEARANCE, COMPRESSION, EXPANSION. 13
pressure, the pressure from compression, the point of ex-
haust closure and the clearance, can be expressed in a gen-
eral formula as follows: Referring to Fig. 3, let/' repre-
sent the back pressure and p" the pressure in the clearance
space at the end of the compression, both measured from
the zero line of pressures ; let / be the point of exhaust
closure, Im the compression curve which is considered as a
rectangular hyperbola, d e the stroke of the piston, and / e
equal k, the clearance as before. Then the fraction of the
stroke at which the exhaust should close to produce/" is:
47— (^-¥
It should be remembered that this formula is but an
approximation, as the real compression curve is not a rectan-
gular hyperbola, but has more nearly the form of the lower
curve in Fig. 4. This modification of the compression
curve is produced by the cooling action of the walls of the
cylinder, the face of the piston, and the walls of the steam
passages, all of which have to be heated to the tempera-
ture of the steam which rises during compression. This dif-
ference between actual and hyperbolic curves, in Fig. 4,
indicates a loss due to clearance. Clearance compels com-
pression, and compression carries with it this type of loss.
The problem of determining the amount of compression
necessary to cushion the reciprocating parts does not differ
essentially in compound and single expansion engines,
except that with compounds the weight of the reciprocating
parts is necessarily greater.
To further illustrate the difference between the actual
curve of compression, and the hyperbolas drawn from any
point in that curve, and to show the decrease of steam
weight during compression, reference is made to Figs. 5
and 6, which show some actual indicator cards taken from
a locomotive. The actual clearance in the engine is 8 per
cent., and is represented by the full vertical lines. The
COMPOUND LOCOMOTIVES.
FIG. 5.
Difference between Actual Curve of Compression and Hyperbol;
CLEARANCE, COMPRESSION, EXPANSION,
FIG. 6.
Difference between Actual Curve of Compression and Hyperbola.
1 6 COMPOUND LOCOMOTIVES.
dotted lines for comparison with the curve of compression,
are hyperbolas, one of which is drawn from a point of the
compression curve after the exhaust valve is closed, and is
based on the actual clearance. This dotted line is always
the one which falls inside of the compression curve. The
other dotted line is an hyperbola that is drawn to approx-
imate closely to the actual curve of compression. This
second line is drawn from the same point of the actual
expansion curve as the first dotted line, and the clearance
which would give this hyperbola is shown by the dotted
vertical line. This would indicate that an approximation
to the actual curve of compression may be made by assum-
ing an hyperbola for the shape of the curve of compression,
and changing the clearance to suit ; that is to say, the
actual compression curve approximates to an hyperbola
based on a greater clearance than is actually used in the
engine from which the cards were taken. The amount of
this greater clearance is given in the illustrations.
These comparative lines on Figs. 5 and 6 are hyper-
bolas, and therefore show less decrease in weight of steam
during compression than would be shown if the curve of
equal steam weight had been used for comparison, as is
evident from Fig. 23a.
CHAPTER III.
MEAN EFFECTIVE PRESSURE.
7. Formula for Calculating Mean Effective Pres-
sure. — For calculating the pressures at the various points
of elementary cards, we can without serious error make
use of the ordinary formulas, and assume that pressures of
steam vary inversely as the volumes, the curves of expan-
sion and compression then being rectangular hyperbolas.
On this basis, the absolute mean pressures for such lines
as a b c, Fig.. 3, are determined by the formula: 43.
This will be recognized as the ordinary formula for
mean pressures, and in which P is the absolute initial pres-
sure, r is the ratio of expansion, i. e., volume at cut-off
divided by volume at end of stroke or at exhaust, as the case
may be, and p is the absolute mean forward pressure. The
absolute pressure is the gauge pressure plus the atmospheric
pressure, which is practically 14.7 pounds per square inch.
The term " hyperbolic " as applied to logarithms refers to
the " Natural " or " Naperian " logarithm. An example of
the application of the above formula will be found in Appen-
dix A. This formula is applicable to such lines of the card
as a b c when a b is parallel to the atmospheric line, as it is
practically in engines supplied from a boiler and working
at slow speeds. For calculating the mean pressure between
b and <:, d and e, e and/^ or for other expansions or compres-
sions in which the part of the card considered is wholly
17
18
COMPOUND LOCOMOTIVES.
within the hyperbola, and where the line of constant pressure
as a b is not included, the following formula is to be used :
hyp. log. r
r —
For example see Appendix B and Appendix F.
8. Difference Between Calculated and Actual
Mean Effective Pressure. — The foregoing method serves
to illustrate what the action of steam in locomotive cylin-
ders is frequently assumed to be, and is worth perusal by
the student ; but for actual practice, the mean effective pres-
sure in either cylinder differs so much from that given by-
FIG. 7.
Reduction of M. E. P. as Speed Increases.
calculation, that the only safe course to pursue is to draw
the preliminary indicator cards by modifying actual cards,
from practice, as is explained further on.
As a more forcible illustration of this difference, Tables.
B, C, D, E, F, G, and H, have been prepared from the
actual indicator cards Figs. 14 and 15, taken from a Sche-
nectady ten-wheel two -cylinder receiver compound on the
Central Pacific Railroad. Columns I, K and L show how
wide is the variation between the calculated and actual
mean effective pressures when the calculations are based on.
MEAN EFFECTIVE PRESSURE. 1 9
the elementary indicator cards. Reference to these tables is
also made under the head of " Cylinder Ratios," chapter VII.
9. Decrease of Mean Effective Pressure as Speed
Increases. — Fig. 7 shows the decrease, in a single expansion
engine, of the maximum mean effective pressure per square
inch of piston, with the best and the ordinary valve gears,
20000
20 4O 6O
SPEED IN MILES AN HOUR.
FIG. 8.
Reduction of Power as Speed Increases.
which follows an increase in the number of revolutions
per minute of locomotive driving wheels. Boiler pres-
sure, 175 pounds per square inch absolute. This shows the
need of careful attention to valve gear dimensions, 77-82.
10. Effect on Draw Bar Pull of Decrease of Mean
Effective Pressure as Speed Increases. — Fig. 8 shows
the decrease in the maximum pull on draw bar of a single
expansion engine which follows an increase in speed of a
19X24 locomotive with 5^ foot driving wheels, with the
best valve gear and with the ordinary valve gear.
2O
COMPOUND LOCOMOTIVES.
11. Increase of Per Cent, of Total Power Consumed
by Locomotives and Tenders which follows a Decrease
of Mean Effective Pressure Due to Speed. — Fig. 9 shows
how the per cent, of total power generated by the cylinders
and consumed by the locomotive and tender together, in-
creases as the speed increases, regardless of any change there
PERCENT. OF TOTAL CYLINDER POWER
CONSUMED BY CARS.
2O 4O 6O 8O
ftO
"*•*•
\
\
\
\
A
\,
X
n
y
n
^
4,
2
V
&
/.
>rt»
fiO
X
fc.
?
f
* I.
N
^
V
\
sj
(t.
^
\
*
\
T
^
^
10
^
-> \
\
\
^
Y
Of)
10(
)
8
0
6
O
4
O
2
O
(
J
PERCENT. OF TOTAL CYLINDER POWER
CONSUMED BY LOCOMOTIVE AND TENDER,
FIG. 9.
Per cent, of Power Consumed by Locomotive at Various Speeds.
may be in train resistance. This is readily deduced from Fig.
8 by comparing the total draw bar pull with the approxi-
mate locomotive resistance.
It is clear from these diagrams that at high speeds almost
the entire power of the locomotive cylinders is consumed
by the locomotive and tender, not because the head air
MEAN EFFECTIVE PRESSURE.
21
resistance, or the locomotive and tender resistance, increases
greatly, but almost solely because of the decrease of mean
effective pressure in the cylinders brought about by wire-
drawing, compression and early cut-off at high speeds. The
worse the design of valve motion and steam passages, the
sharper will be the inclination of the curve in Fig. 9 to the
1-eft. A misunderstanding of the real condition on the part
of some writers has led to the conclusion that this inclina-
tion is due to a great increase in head air resistance The
fallacy of such a conclusion appears at once from an exam-
ination of Figs. 7, 8 and 9.
Fig. 10 shows the advantage of using a large driving
3O 35 4O 45 SO 55 €0 65 TO 75 8O
SPEED IN MILES AN HOUR.
85 90 85 100
FlG. 10.
Effect of Large Drivers on M. E. P. at High Speed.
wheel on a locomotive. All that this diagram, Fig. 10,
shows, applies with greater force to compounds, as the loss
in power with compounds increases more rapidly as the
speed increases than with single expansion engines. The
mean effective pressure given in Fig. 10 is that which
will be obtained when the steam valves are controlled by
the best types of valve motion now used, and when the
boiler pressure is 160 pounds per square inch by gauge.
Figs. II and 12 show very . clearly how the mean
effective pressure is reduced as the speed increases in a
Vauclain compound. These cards, Nos. I to 13, were taken
from a ten-wheel freight engine on the Chicago, Milwaukee
22
COMPOUND LOCOMOTIVES.
& St. Paul road. Table A gives the data calculated from
these cards, and Fig. No. 13 is a diagram showing the
decrease of mean effective pressure as the revolutions per
minute increase. These cards are intended to illustrate
FIG. ii.
Actual Indicator Cards Showing Decrease of M. E. P. as Speed Increases.
what takes place in any engine, compound or single expan-
sion, as the speed increases, and shows how the hauling
power of a freight engine decreases as the speed increases.
Card No. I shows, perhaps, more clearly than any of the
others how compression and wire-drawing robs the engine
of its power at high speed. From this it is clear that
if a locomotive is proportioned so that its cylinder power
MEAN EFFECTIVE PRESSURE.
10
FIG. 12.
Actual Indicator Cards Showing Decrease of M. E. P. as Speed Increases.
INVOLUTIONS ren MINUTC
FIG. 13.
Diagram Showing Decrease of Hauling Power as Speed Increases.
COMPOUND LOCOMOTIVES.
at low speed is just about sufficient to slip the wheels, it will
have far too little cylinder power to slip the wheels at high
speed. This then is an illustration of the need of an increase
of cylinder power to haul heavier trains at high speeds, and
it is evident that the simplest and best way to increase
the cylinder power is to reduce the wire-drawing and com-
pression.
TABLE A,
Giving Data "with Reference to Indicator Cards Nos. i to /?, taken from
a Ten-Wheel Vauclain Compound Freight Engine on the Chicago, Milwaukee
and St. Paul Railroad.
No. of card. -
i
2
3
4
5
6
7
8
9
10
ii
12
13
No. of reverse
lever notch.
i
1
i
ifc
*%
i#
2
2^
2^
2^
2^
2^
7
Cut-off h.p. cy-
linder,inches.
12.25
12 25
12 25
13 25
13.28
1328
14 25
15 41
J5 44
IS 44
I5-4I
I5-4I
21.62-
Cut-off 1. p. cy-
linder,inches.
15.06
15 oo
15.06
15 94
15 9°
*5-9°
16.87
17 62
17 75
*7 75
!7-63
I7.63
22.75,
Revolutions per
minute. - -
256
256
228
244
232
140
188
192
172
156
120
80
48
Boiler pressure,
absolute - -
191
I9I
l85
185
183
189
192
190
192
1 86
190
l85
191
Mean effective
pressure, h. p.
cylinder.
37 5°
41 25
4O.OO
51 88
47 50
64.50
68 75
70.00
75 °°
78 75
82.50
81.25
116. 25.
Mean effective
pressure, 1. p.
cylinder. -
13 75
12 50
15 oo
15 oo
20.00
25.00
22 50
28.75
25 oo
27 5°
37.50
38.75
46.25
Mean effective
pressure, 1. p.
cyl., reduced
to equivalent
for h. p. cyl.
Prop o r * i o n a 1
40 43
34 75
44 10
41.70
58.80
73-50
62-55
84 52
69.50
76.45
110.25
"3-93
128.56
No. showing
com para t i v e
haul ing power
1.025
I CO
i 107
1.231
1-399
1.816
I 728
2.033
i .901
2.042
2.535
2.568
3.221
Pressure at ad-
mission to h.
p. cylinder.
165
*75
168
178
168
173
180
170
176
171
176
168
167
CHAPTER IV.
DIFFERENCES BETWEEN ELEMENTARY AND ACTUAL
INDICATOR CARDS.
12. Difference between Apparent and Actual Cut-
off.— Figs. 14 and 15 show a set of actual indicator cards
from a two-cylinder receiver compound of the Schenectady
type on the Southern Pacific Railroad, having the following
general dimensions :
Diameter of H. P. Cylinder 20
" L. P. " 29
Stroke of Pistons 24
Diameter of Drivers 69
Number " " 6
Weight on " 96,680
" of Engine, loaded 129,700
' Tender,
Heating Surface 1736.2
Grate " 29.26
Heating per sq. ft.
of Grate 60.7
Heating Surface per sq. in.
Cyl. Area, L. P. 2.63
inches Outside lap of Valve, H. P. il/% inches
" " " L. P. \y% "
Inside Clearance, H. P. j5^
L. P. ft "
Size of Steam Ports, H. P. Cyl. 2^x18
Ibs. " " " " L. P. " 2^x20
" Exhaust '* H. P. " 3x18
" L. P. " 3x20
sq. ft. Cyl. Area per sq. in. flue open-
ing 1. 1 1 sq.in
Per cent, of Weight on Drivers 74-54
Clearance H. P. Front 1026 cu. in.
" " Back 1178 "
" L. P. Front 1386
" " Back 1220
Table B shows the difference between the "actual" cut-
off, taking into account the clearance, and the "apparent"
cut-off measured from the valve motion when the engine is
out of service, and ^ not as taken from indicator cards, and
does not therefore include lost motion and springing of
the parts. The difference between these is so great as
to emphasize the need of always basing calculations and
examinations on the actual instead of the apparent cut-off.
This table also shows the effect of clearance in increasing
the actual cut-off beyond the apparent cut-off.
25
26
COMPOUND LOCOMOTIVES.
TABLE B.
Showing the difference between the "Actual" Cut-off, counting the Clear-
ance, and the "Apparent " Cut-off, Measured from the Valve Motion when the
Engine is out of Service, and not taken from Indicator Cards.
Actual
Card No.
A
Revolutions
per
minute.
B
Miles per hour.
E
Piston speed in
feet per minute.
c
Actual cut-off
including clear-
ance. Per cent.
HP L P
D
Apparent cut-off
Per cent.
HP L P
I
2
3
4
6
7
8
9
30
50
60
144
1 80
240
240
300
330
6.16
10.26
12.32
29.56
36.95
49.27
49.27
61.58
67.74
120
200
240
576
720
960
960
1200
1320
86.4
83.8
76.6
68.2
58.4
58.4
50.2
50.2
50.2
87.3
84.2
78-5
71.2
61.6
61.6
55-1
55-1
55-i
84.5
81.2
73-o
63-5
52.1
52.1
42.7
42.7
42-7
86.
82.8
76.8
68.8
58.5
58.5
51-5
51-5
5i-5
13. Difference between Actual and Elementary
Mean Effective Pressures in High- Pressure Cylinder. —
Table C gives the elementary or theoretical mean effective
TABLE* C.
Showing the Elementary or Theoretical Mean Effective Pressure in the
High- Pressure Cylinder, based on the Elementary Indicator Cards and on
Boiler Pressure.
C(h.p)
F
G(hp)
H
I
K
L
Fi
Is ^
jo*--
jw"!
'£. V
y-^J 8 ^ g g
I.S-S
"s 3--
t; 1 S
1 &
«sr
«|
N
* ^ s| o-|
iC ^ ^
1 11
c|||
d
fc
i*
s S3
</> a.
||
•|f2
i^g'G^ll.s
cd|
|*|
^ iT ** i—
M 0 >>
1
S1*"1
If
£1
a|
Ej
aj^.S
rt fij
'" "Z « 8 !y 8J
u ^ Ja ^ £ << a
Si
l]jj
— 5^2 u
.0 SS"S d
o
I js
c
oj .
If
60
rt "g C/3
•II
S?«
%ii!il
"^ 1 S3
S3 e « ^
411
:
86.4
152
151
58
92.3
89.1
96.8
165-3
2
83.8
142
142
54
84.9
83.2
98.0
153-9
3
76.6
152
152
54
93-o
83.0
89.2
162.0
4
68.2
150
149
50
88.5
83.6
94-5
153-5
5
58.4
I 60
157
47
93-8
54-2
57-8
155.8
6
58.4
I 60
1 60
46
94-8
42.4
44-7
155-8
7
50.2
I 60
1 60
46
86.0
32-9
38.3
147.0
8
50.2
I 60
1 60
45
87.0
31-3
36.0
147.0
9
50.2
165
165
45
91.2
31.0
34-0
151 .2
ELEMENTARY AND ACTUAL INDICATOR CARDS. 27
pressure in the h. p. cylinder, based on elementary
indicator cards and on boiler pressure, and includes no con-
sideration of clearance or compression, the back pressure
being taken equal to the average receiver pressure. This
is compared with the actual mean effective pressure, and
shows how great is the reduction of power, and to some
extent economy, resulting from wire-drawing and com-
pression.
TABLE D.
Showing the Theoretical Mean Effective Pressure in the High-Pressure
Cylinder, based on the Elementary Indicator Card, and with other assumptions
used for Table C.
C (h. p.)
F
G (h. p.)
H
J
K
M
bfi
C
'O
3
"u
-I
rt
CUD
II
i!
> S3 « i'S Ji'-o
||:IHi
V •
•=l
If
.§5d
H £*
o — e
0
•sg
O y
£.
K-S
SJ
^
|l
id|llig-
« 51
Bft-S
iij
•E
tj
« sr
ijj
s y
_ x « £ a 8 '^
l-fig"
6
ft W
D t/5
^
i-sc^|ii
^•Sft
g'll _
"«
g C
_S «
^ •
2 &c
2- H ^ &£^Q rt ^ *^
« w
U QJ ^ a;
2
tl 2
SB
S 3-a
o
JH «
rh &JO-"
U x S
« S 5 c
<j
< s
PQ ^
O c .
<J 2n .
f^Snuo^Urt^fa
^ ™ o^,
"y
fin
'5 sr
S^
a^ 'Si « 2 ^ o.
ft(£
I
86.4
152
151
58
91-3
89.1
97-8
2
83.8
142
142
54
84.9
83-2
98.0
3
76.6
152
'52
54
93-o
83.0
89.3
4
68.2
150
149
50
87-5
83.6
95-6
5
58.4
I 60
157
47
91.1
54-2
59-5
6
58.4
I 60
1 60
46
94.8
42-4
44-7
7
50.2
I 60
1 60
46
86.0
32.9
. 38.3
8
50.2
I 60
160
45
87.0
3i-3
36.0
Q
50.2
165
165
45
91.2
31.0
34-0
Table D shows the theoretical mean effective pressure
in the h. p. cylinder based on elementary indicator cards
and on the pressure at the beginning of the stroke,
and with the other assumptions used for Table C. This
shows the loss in power, and to some extent economy,
resulting from wire-drawing and compression. The close
approximation of the results given in Tables C and D is due
to the important fact that this two-cylinder compound, Figs.
14 and 15, has very large throttle valve and steam pipes,
28
COMPOUND LOCOMOTIVES.
CLCArtANCt.
-l026cu.iNS.
/MX..P.'
•87.574
MJC..P.'
90.53SN
1 CLEARANCE.
1-1176 cu. INS.
120
100
£0
60
^Q
f9
1
\
1
\
A
84.195^-
7^
^
^L&
120
s~
^y
_qo
130
0
\/
8ljS3t \/
A\
/v
F.END.
eo.
50
lo
IO
TcT
45044 /
^^-r^
^^ -~—
^5^6^
^^
^X
(/
\
f\
7
^-X^
j~~*
54.36 ><^^^ 54.07
J\
160
£5.756
FIG. 14.
Indicator Diagrams from Two-Cylinder Receiver Compound.
ELEMENTARY AND ACTUAL INDICATOR CARDS. 2Q
F END.
B.END.
6.
M.EJ?- agaeg
ifl !Sf
ZIOO
B. END.
60
n
UK.
7.
9.
FIG. 15.
Indicator Diagrams from Two-Cylinder Receiver Compound.
and was operated with a full open throttle. There was but
little, if any, loss in steam pressure between the boiler
and the steam chest.
14. Differences between Actual and Elementary
Mean Effective Pressures in Low-Pressure Cylinder.—
Table E gives the theoretical mean effective pressure in
the 1. p. cylinder based on the average receiver pressure,
the actual cut-off, and on 5 pounds per square inch back
pressure, and the other assumption used for Tables C and D.
30
COMPOUND LOCOMOTIVES.
This shows the loss in power, and to some extent the loss
in efficiency in the 1. p. cylinder due to wire-drawing and
compression, and shows the futility of any attempt to
use the common theory of steam engines deduced from
elementary indicator cards when designing compound
locomotives under the ordinary conditions and with the
ordinary valve gears and ports.
TABLE E.
Showing the Theoretical Mean Effective Pressure in the Low-Pressure
Cylinder, based on the Average Receiver Pressure, the Actual Cut-off, on
Five Pounds per Square Inch Back Pressure, and the other Assztinption w-.9<:Y/ for
Tables Cand D.
C (1. p.)
H
N
0
P
E i
0
£
•o
II
u w
.£ 2fc
8 «'"
4) M 0-
MjfjHiJ
c s •
11*1
«- D ^ g
e i> • • ^
8 = oM
i|2||
5
?£
u u
— X
4) V
.5 & « "' a-" | n
- $- ?
"o c jf'n ^
*: S 5 -2 -a
"5a?^ »
— n
of -a yudo ~-^> • c.
- ^^0-
S E * °.S
w ^^ T
r;
<
1 61 1
<^ h
£5-3 |g.2 :_McSl'g-
^ " § E ^~ «'«-'" y * ''
"^QJ^ r"^ H- ** « y e '^^ir
~ > a-
5"s^f"^
u U O ^^
S-^s^-S
H'^^3
! -Scu
*sj — 2-i
S~i_:
^SiS
i
87-3
58
52.3
50.9
97-4
52.4
2
84.2
54
49.6
46.2
93-o
49-5
3
78.5
54
47-6
44.8
94.0
49-5
4
71.2
50
41.8
32.5
77-6
47-4
5
61.6
47
36.4
24.4
67.1
42.8
6
61.6
6
35-5
20.1
56.6
43-8
7
55-i
46
33-7
16.4
48.6
39-o
8
55-i
45
32.8
13.2
40.3
37-2
9
55- i
45
32.8
15-4
46.9
39-8
Table F gives the theoretical mean effective pressure
in the 1. p. cylinder, based on the admission pressure,
and with the other assumption as given for Table E. This
table also shows the loss in power and to some extent
the loss in efficiency, resulting from compression and wire-
drawing in the 1. p. cylinder.
ELEMENTARY AND ACTUAL INDICATOR CARDS.
TABLE F.
Showing the Theoretical Mean Effective Pressure, in the Low-Pressure
Cylinder, based on the Admission Pressure, and with the other Assumption
given for Table £.
£
C (1. p.)
H
D i
o
Theoretical mean effective pressure
1
3
Actual cut-off
including clear-
ance. Per cent.
Average r e -
ceiver pressure,
gauge. Pounds
per .sq. in.
for 1. p. cylinder, based on admission
pressure, on 5 Ibs. per sq. in. back
pressure, and on the same compres-
sion that is found in Corliss engines.
Actual mean
effective pressure
in 1. p. cylinde".
Pounds per sq. in.
<
Pounds per sq. in.
I
87-3
58
52.3
50.9
2
84.2
54
49-5
46.2
3
78.5
54
49-5
44.8
4
71.2
50
47-4
32.5
5
61.6
47
42.8
24.4
6
61.6
46
43-8
20. I
7
55-i
46
39-0
I6.4
8
55-i
45
37-2
13.2
9
55-i
45
39-8
15-4
15. Differences Between Actual Work done in Cylin-
der and the Work shown by Elementary Indicator Cards.
—Table G shows the difference between the actual work
done in both cylinders of the compound two-cylinder loco-
motives under consideration, and the work that would be
given by calculation based on elementary indicator cards
in which the steam was assumed to expand from the vol-
ume at cut-off in the h. p. cylinder, and with the pressure at
admission in the h. p. cylinder, to the volume correspond-
ing to the final volume of the 1. p. cylinder, and illustrates
the errors in some of the theoretical formulas offered for
compound locomotives, more particularly in foreign tech-
nical publications. Such formulas as these have been used
in argument about compound locomotives, and have gener-
ally led to conclusions entirely different from the results of
actual trials of real locomotives.
To some extent this table also shows the loss in effi-
ciency of compound locomotives due to inadequate valve
motion, steam passages, and high speed, when compared to
a good stationary compound engine, or a marine compound
having better valve motion and running at slower speed.
COMPOUND LOCOMOTIVES.
TABLE G.
Showing the Difference between the Actual Work done in both Cylinders, and
the Work that would be given by Calculation based on Elementary Indicator
Cards.
0
*r.
Z
A i
B i
C i
Actual Card ]
Absolute pres-
sure at admission,
h. p. cylinder.
Absolute pres-
sure at end of
expansion, 1. p.
cylinder.
Actual work done in
both cylinders per
revolution, foot pounds,
calculated for the pur-
pose of comparing
with column (C i).
Theoretical work in both cylin-
ders based on expansion in ele-
mentary engine from actual
pressure at admission in h. p.
cylinder, to pressure correspond-
ing to final volume in 1. p. cylin-
der, including clearance.
I
166
55
246,000
467,000
2
157
55
226,100
433,000
3
167
49
222,300
439,000
4
164
40
190,500
389,000
5
172
30
132,300
383,000
6
175
30
106,300
393,000
7
175
25
84,700
353,000
8
175
23
74,200
353,ooo
9
180
23
79,600
364,000
However, the difference in the power as given does not
represent fairly the loss in efficiency. Loss in power does
not necessarily indicate loss in efficiency ; in fact, the loss
in efficiency is very much less than the loss in power indi-
cated by this table.
16. Indicator Cards in Practice. — In making a theo-
retical analysis of a proposed design of compound engine,
the most important thing to do is to bear in mind the dif-
ference that exists between elementary indicator cards,
on which such mathematical analysis is generally based, and
actual indicator cards from practice. The causes which
produce the differences are chiefly the initial condensation,
re-evaporation during expansion, the size, shape and loca-
tion of the steam passages and receiver ; the opening of
the exhaust before the end of the stroke ; compression and
wire-drawing due to the slow opening and closing of the
ports, as well as the effect of the steam distribution bv the
existing types of valve motion. The following are some
examples of the differences usually found between the ele-
mentary and the actual indicator cards :
ELEMENTARY AND ACTUAL INDICATOR CARDS. 33
17. Drop in Pressure During Admission, High-Pres-
sure Cylinder. — Fig. 16 shows an indicator card from a
compound locomotive in which steam was cut off at about
-fa of the strpke in both cylinders, as shown by the full line.
The clearance space is 10 per cent, of the piston displace-
ment in the h. p. cylinder, and 7.5 per cent, in the 1. p.
FIG. 1 6.
Cards Showing Drop of Pressure During Admission.
cylinder. The volume of the receiver is one and one-half
times the h. p. cylinder. With this data the theoretical
lines shown dotted in the figure have been constructed,
making allowance for the excessive drop shown between
the two cards. The differences between the actual admis-
sion and expansion lines of the h. p. card are the same as
in cards from single expansion engines, and are due to the
wire-drawing during admission and at cut-off, and to the
re-evaporation during expansion.
18. Rise in Pressure During Admission, Low-Pres-
sure Cylinder. — It will be seen from indicator cards, Figs.
14 and 15, that there is an increase in pressure in the 1. p.
34
COMPOUND LOCOMOTIVES.
cylinder and in the receiver after the 1. p. piston has
moved somewhat from the end of the stroke. This is per-
haps more pronounced in card No. I, Fig. 14, taken at slow
FIG. 17.
Difference Between Actual and Elementary Admission and Expansion Lines.
speed. This arises from the fact that the opposite end of
the h. p. cylinder exhausts at this time, and thus increases
the steam pressure in the receiver, and also in the 1. p.
cylinder. This action will always be found when the
exhaust from the h. p. cylinder takes place before cut-off
in the 1. p. cylinder. This action is called "re-admission."
It is not likely that with the ordinary valve gear, the h. p.
exhaust in any compound locomotive will occur later than at
90 per cent, of the stroke, and the 1. p. cut-off will not gen-
erally be earlier than -^ of the stroke, and hence it is
ELEMENTARY AND ACTUAL INDICATOR CARDS. 35
safe to say that re-admission will always occur in prac-
tice. The practical effect of this is to make the 1. p.
admission line more nearly parallel with the atmospheric
line, or, in other words, causes the 1. p. admission line to
more nearly resemble the admission line of a card from a
single expansion engine.
In Fig. 17 are shown the admission and expansion lines
of four indicator cards from the 1. p. cylinder of a com-
pound locomotive. The points of cut-off given are those
which were recorded on the cards. The dotted lines indi-
cate the form of the theoretical card for these points of cut-
off and for the initial pressures as shown.
On card No. 6 a curve which agrees with the actual
curve very closely is indicated by dots, and shows an ear-
lier cut-off than that recorded. On card No. 9 the irreg-
ular dotted line shows the form of the card from the other
end of the cylinder with the same nominal point of cut-off.
19. Effect of Speed on Shape of Indicator Cards.—
The extent of departures from the assumed theoretical
curve varies greatly in simple engines, and principally
depends upon the piston speed, valve gear, and size of
steam passages. The only satisfactory way of determining
the probable loss in a proposed engine, whether simple or
compound, is to examine indicator cards from an existing
engine of the same general proportions, and having a valve
gear of the same type and dimensions. Indicator cards
taken from engines of various makes when on similar ser-
vice show variations of as much as 20 per cent., and it is
obvious that no general rule can be laid down which will
give the results that may be expected in any given case, as
the conditions which affect the actual indicator cards are
not only numerous but variable as well.
For example, in Fig. 16, when the h. p. exhaust occurs
at #, the 1. p. piston is at n, and re-admission to the 1. p.
cylinder takes place, causing a rise in pressure to m. The
30 COMPOUND LOCOMOTIVES.
1. p. piston moves from this position to that of cut-off/
T40- of the stroke, before the h. p. piston has moved
over the remainder of its stroke from b to c. The pressure
at c was calculated approximately on the basis of the
receiver pressure when the h. p. exhaust opened, being that
at / From c to d there is some compression as shown.
— 160
H. P. Cut-off.
L.P. " " 73%
Rev. p. min. 147
FIG. 1 8.
Actual Indicator Cards at Different Speeds.
Turning now to the 1. p. card, and taking the pressure at e
as that of the steam in the receiver, we find that the line
from e to n is practically at constant pressure, and that the
rise in pressure from n to m is comparatively slight. Also,
that during the expansion of the steam in the receiver from
m to /the fall in pressure is not great. The drop between
the h. p. and the 1. p. cards in this figure is excessive.
In Figs. 1 8 and 19 are shown indicator cards from two-
cylinder compound locomotives at different speeds and
ELEMENTARY AND ACTUAL INDICATOR CARDS. 37
points of cut-off. The shape of the h. p. back-pressure line
is to be noted. Cards Nos. 2 and 3 are from the same
engine, and it will be noticed that the compression up to
about the middle of the back stroke is quite marked, and
— 140
H. P. Cut-off, 80°*
L.P. » » 40%
Kev. p. min. 160
FIG. 19.
Actual Indicator Cards at Different Speeds.
that the remainder of the back pressure line is nearly
horizontal, as it was found in Fig. 16. In Nos. 4 and 5 the
compression appears to continue during the whole of the
back stroke. This is the case in a considerable number of
cards which have been examined, and is particularly notice-
able at high speeds.
CHAPTER V.
EFFECT OF CHANGING THE POINT OF CUT-OFF—PRESSURE
IN THE RECEIVER.
20. Effect of Changing Cut-off in Elementary Engine.
—Perhaps the clearest way of indicating the general effect
on the work done in the cylinders by changing the point of
cut-off is to analyze the elementary engine and see the
effect in it. In practice there is so much wire-drawing,
particularly in the 1. p. cylinder, that a change in the point
FIG. 20.
Effect of a Change in Point of Cut-Off.
of cut-off does not affect the power generated in the cylin-
der as much as in the elementary engine. Also, in cases
where the receiver is small, a change in the cut-off in the
1. p. cylinder is not always followed by a proportionate
change in the mean effective pressure in that cylinder
To illustrate what takes place in the elementary engine
when the cut-off is changed, reference is made to Fig. I.
Under the conditions assumed for that illustration, if the
38
CHANGING CUT-OFF — PRESSURE IN RECEIVER. 3Q
h. p. cut-off is made earlier, while the 1. p. cut-off remains
as before, at one-half stroke, a series of changes will be
introduced, which are shown in full lines in Fig. 20, the lines
of Fig. I being repeated in dotted lines. Assuming a cut-
off at 3/6 stroke, the final pressure in the h. p. cyl-
inder is i6oxf=6o pounds, or at c' instead of c. Also,
as the total expansion is now 2.5 Xf =2y°=6-f instead of 5,
the final pressure at g is reduced to g' , which represents
1 60 X 2%-= 24 pounds. Then, as the 1. p. cut-off is un-
changed, the pressure at /is reduced to f , or 24x2 = 48
pounds. The steam which fills the h. p. cylinder at a
pressure of 60 pounds is mixed with an equal volume in the
receiver at a pressure of 48 pounds, giving a resulting
pressure at d of 54 pounds. The results of this change
are, then, that the pressure in the receiver, the initial pres-
sure in the 1. p. cylinder, and the mean pressure in that
cylinder, are all less than before. The work done by the
1. p. cylinder is therefore less, while for the h. p. cylinder
we have taken from one part of the card and added to
another part. The total work done by both cylinders is,
of course, less than before, but the proportion done by the
h. p. cylinder is greater, and, in fact, the mean effective
pressure in that cylinder has been increased.
With both cut-offs at the same point, considerably more
work is done in the 1. p. than in the h. p. cylinder, but by
making the h. p. cut-off the earlier of the two there is less
difference in work than before, or, in other words, the work
may be equalized by this means. A similar effect will, of
course, be produced by making the 1. p. cut-off later than
that of the h. p., and conversely by making the 1. p. cut-off
earlier than that of the h. p. the proportion of the total
work which is done by the 1. p. cylinder will be increased.
The following table, calculated for R—2 and C=i.$ v, will
illustrate this :
COMPOUND LOCOMOTIVES.
Showing the Effect of a
Compound Engine.
TABLE H.
Change in Point of Cut-off in an Elementary
Cut
h. p.
-off.
I. p.
Mean
press,
h. p.
Mean
press.
1. p.
Mean h. p.
press, referred
to 1. p.
Total mean in
one cyl.
Prop
of \v
h.p.
Drtion
ork.
l.p.
1-
1
46.6
54-o
23-3
77-3
•3
•7
&
1
51.4
39-6
25-7
65-4
•4
.6
f
39-2
48.9
19.6
68.4
.29
•7i
i
*
31-5
60.3
15-7
76.0
.21
•79
21. Effect of a Change of cut-off on the Receiver
Pressure in an Elementary Engine. — In locomotive
practice the pressure in the receiver is less than that cal-
culated, on account of losses in the h. p. cylinder and
passages. The effect of a lower receiver pressure is to
increase the proportion of work done in the h. p. cylinder,
so that by adjusting the valve gear to give an earlier cut-
off in the h. p. cylinder than in the 1. p., the total work
may be very nearly equally divided between the two
cylinders of an elementary engine, and can be divided
with sufficient approximation to equality in a well designed
locomotive.
In Figs. I, 2 and 3 the 1. p. cut-off has been taken at
one -half stroke, and it was assumed that release occurred
in the h. p. cylinder exactly at the end of the stroke. If
now we make the 1. p. cut-off later than one -half stroke,
leaving everything else unchanged, there will be an
exhaust from the h. p. cylinder, while the 1. p. steam
valve is still open, which will increase the pressure in the
receiver and cause what may be called a re -admission in
the 1. p. cylinder. This is illustrated by Fig. 22, in which
the h. p. exhaust occurs at b, causing a rise in pressure to
c, from which there is expansion as before in the h. p.
cylinder, the receiver and the 1. p. cylinder until the 1. p.
steam valve closes at d. A similar effect will be produced
by pre-release in the h. p. cylinder. See Figs. 14 and 15.
CHANGING CUT-OFF PRESSURE IN RECEIVER. 4 1
An examination of a diagram such as Fig. 21 may make
this subject more clear. In this Fig. b c represents the
stroke of the pistons, and the circle the path of the crank
pins. Taking the direction of revolution as indicated by
FIG. 21.
Diagram of Crank Location, Two-Cylinder Compound.
the arrow, when the h. p. piston is at the end of a stroke,
or its crank is at a c, the 1. p. crank will be at a c' , and the
FIG. 22.
Rise in Pressure During Admission to 1. p. Cylinder.
exhaust from the h. p. cylinder which takes place at this
position of the cranks will cause the rise in the 1. p. card
shown at c, Fig. 22. If the h. p. exhaust occurs before the
end of the stroke, for example when the piston is at d,
the 1. p. crank will be at a e' , and the 1. p. piston at g,
causing a rise in the 1. p. card as shown at k, Fig. 22. In
cards taken from an engine this increase in pressure will,
of course, be more gradual, and at high speeds may simply
cause the 1. p. admission line to be more nearly parallel
with the atmospheric line. This arises from the high
42 COMPOUND LOCOMOTIVES.
piston speed and the consequent wire -drawing of the
steam through the ports and past the valves.
22. Equalization of Work in the High and Low
Pressure Cylinders of a Receiver Compound. — The
nearer the action of the steam in a compound locomotive
approaches the action in the elementary engine, the more
readily can the power generated in the two cylinders be
equalized at all cut-offs by an alteration of the cut-offs
in the cylinders, and the reverse is also true ; namely,
that where the receiver is small and the wire-drawing
and compression excessive, it is well nigh impossible
to equalize the power generated in the two cylinders
at all cut-offs by adjusting the cut-offs.
Some of the first compounds built in this country had
much wire -drawing and compression, and had small
receivers, and it was found practically impossible to
equalize the power by changing the cut-offs. After some
considerable experiment the receivers were increased and
the compression was very considerably reduced by cutting
out the inside of the steam valve, more particularly on the
h. p. cylinder, so as to give what is termed " inside
clearance" or negative lap, 80. On a 5^ inch travel, the
amount cut out on each side was as much in one case as
y2 of an inch. This clearance delays the point of exhaust
closure and decreases the amount of compression. The
result of these changes, when taken together with the longer
steam ports now used, has been to put the two -cylinder
compound locomotive at this time in very good shape, so
far, at least, as the equalization of the work between the
cylinders is concerned. This appears from Table I, for
instance, which shows how perfectly the work is equalized
in the Schenectady ten -wheel compound on the Central
Pacific Railroad.
It is not expected that when a locomotive is starting a
train and steam is used directly from the boiler in the 1. p.
CHANGING CUT-OFF PRESSURE IN RECEIVER. 43
cylinders, that the work will be equalized in the h. p. and
1. p. cylinders of any compound engine.
TABLE I.
Showing the Equality of Work in the High and Low-Pressure Cylinders
of a Schenectady Two- Cylinder Compound Ten-Wheel Locomotive.
Cut-off h. p.
Cylinder.
Inches.
Cut-off I. p.
Cylinder.
Inches.
Per cent, of total
work done in
h. p. Cylinder.
Per cent, of total
work done in
1. p. Cylinder.
20^
20^8
45-o
55-0
19%,
• 19%
45-8
54-2
17 y^
18/8
46.5
53-5
l$l/i
16^
47.8
52.2
12%,
14^5
51.0
49-0
12l/2
I4M
49-7
50.3
ic>X
12/8
48.5
Si-5
IOJ^
12/8
52-7
47-3
ioX
12/8
48.5
51-5
23. Equalization of Work in the High and Low-
Pressure Cylinders of a Non-Receiver Compound. — In
the four-cylinder type of engine, which includes the tandem,
Vauclain and Johnstone compounds, it is not necessary,
either for the purpose of starting trains or for steadiness of
motion of the engine, to equalize the work done in the
cylinders. This appears from the fact that the two sides
of the locomotive are duplicates of each other. However,
in the Vauclain engine, in order to favor the peculiar con-
struction of the crosshead, in which the centres of the
piston connections do not coincide with the centre of
the main road bearing, it is very desirable to equalize the
pressure at all parts of the stroke rather than the zcw/£
done per stroke, and this brings in a new problem quite
complicated in its nature, and which is not considered in
the foregoing. This will be considered in the description
of the Vauclain type of engine, as it has to do only with
that particular construction, 121.
44
COMPOUND LOCOMOTIVES.
24. Conclusions about the Equalization of Work
in High and Low-Pressure Cylinders. — In the two-cyl-
inder receiver compound it is desirable to equalize the work
done at all points of cut-off in the two cylinders except
at starting, so that the difference will not be more than
about 10 per cent. 20-23. In the tandem compound, it is not
necessary or very desirable to equalize either the work in
the cylinders or the pressures on the piston rod. In the
Vauclain type of engine, 120, it is not necessary or very
desirable to equalize the work done in the two cylinders, but
it is quite necessary to approximately equalize the total pres-
sures on the piston rods at different points of the stroke, in
order to prevent a twisting tendency of the crosshead.
This equalization cannot be made when steam is admitted
directly from the boiler to the 1. p. cylinder, yet it has been
quite well equalized in some engines when running under
normal conditions. In calculating the total pressures on
the piston rod of the Vauclain engine to determine the
equalization, it is necessary to include the pressures on the
crosshead which result from the inertia of the piston, and
this makes the calculations rather complicated. In a high
speed engine, such as a locomotive, the inertia of the piston
rod and piston modifies materially the total pressure on the
piston rods. See Appendix P.
25. Pressure in the Receiver. — The variation of the
pressure in the receiver, as shown on the lines d, e, f,
Fig. I, depends upon the capacity of the receiver com-
pared with the capacity of the h. p, cylinder and the
1. p. cylinder up to cut-off. For example, see Ap-
pendix E. As a further illustration of this, the follow-
ing table shows the pressure at the points d, e and f, with
receivers having capacity 1.5 and 2 times the capacity of
the h. p. cylinder and with the 1. p. cylinder capacity from
2 to 2.5 .times the capacity of the h. p. cylinder, 53. It must
be remembered that the results in this table are based upon
CHANGING CUT-OFF PRESSURE IN RECEIVER. 45
elementary indicator cards and not actual indicator cards,
and are offered only in the way of illustration, and not for
guidance in actual work, 12-19. The actual pressure in the
receiver is materially modified by the action of the valve
motion, the wire -drawing of the steam through the ports,
and the compression in the 1. p. cylinder.
Pressure
atrf.
Mean
press. bet.
d and e.
Pressure
at e.
Mean
press.bet.
e and/.
Pressure
at/.
Mean
press, in
receiver.
C — v R — 2
80
01 8
1 06 7
01 8
80
91 8
C — T 5 v R — 2 .
80
88 Q
100
88 9
80
88 9
C — 2 v R — 2
80.
87.4
06.
87 4
80
87 4
C — v, R = 2.$
72.
82.6
96.
77-8
64
80.2
C = 2 v, R = 2.$
69.3
75-7
83.2
72.4
64
74.
The table shows that the receiver pressure may vary
during one stroke as much as 27 pounds, and that, gener-
ally, the pressure at / the cut-off in the 1. p. cylinder,
will be below the admission pressure to that cylinder, and
while it would appear from the table that the mean pressure
up to cut-off, from e to f, does not differ much from the
mean pressure in the receiver, yet, in fact, there is a con-
siderable difference between these mean pressures, because
of the wire-drawing of the steam through the port and past
the valve of the 1. p. cylinder. See Figs. 14 and 15.
In designing compound locomotives, the pressure in the
receiver has been frequently assumed as constant. This
assumption gives very simple formulas for receiver capacity
and mean effective pressure, yet such foimulas have no
practical application, as the receiver pressure varies con-
siderably in locomotive work owing to the irregular action
of the valve motion and the wire-drawing and compression,
12 19. Some technical writers, more particularly in foreign
publications, have deduced some quite simple mathematical
expressions for the proper proportion of cylinder volume,
receiver volumes, and points of cut-off, but these formulas
46 COMPOUND LOCOMOTIVES.
have no practical application, for reasons that have been
given, and because of further and incidental conditions that
are imposed on locomotives. See Appendix K.
In most cases it is well-nigh impossible to pre-determine
the receiver pressure by calculation, and the only safe way
to proceed is to select actual indicator cards, of which
there are now a great many available, from similar engines
in practice, arid make such changes in the actual cards as
judgment and experience dictate, being guided in this by
the differences between the proposed design and the actual
similar design that has been tested in practical service.
However, the table shows clearly one important fact. It is
that the larger the receiver, the smaller are the variations
of pressure in it. A further analysis of the practice in this
respect is given under 45—56.
Upon the receiver pressure depends, to a great extent,
the division of work between the cylinders, 50-51, and in an
elementary engine or a slow moving locomotive the
division of power may entirely depend upon this factor ;
but in an actual engine moving at considerable speed, the
wire -drawing and compression so modifies the action of
the steam that the control of the power distribution does
not lie with the receiver pressure. Any useful rule for
receiver pressures must necessarily be based almost entirely
on the results from actual indicator cards, and will not be
applicable to engines differing much in design.
If the pressure maintained in the receiver of an engine
in practice is known, the probable receiver pressure in a
similar proposed engine can be predicted ; but when a
quite different arrangement of valves and passages is used,
the distribution in previous engines will be of little service
as a guide in making estimates of receiver pressures.
When a compound locomotive is moving slowly, the
wire-drawing and compression, 6-11, is not so much a factor
in the distribution of power between the cylinders and in
CHANGING CUT-OFF PRESSURE IN RECEIVER. 47
controlling the receiver pressure, and, therefore, an approx-
imate calculation can be made with more satisfaction than
for conditions when the locomotive is at speed. The
following is a method of approximating to the probable
receiver pressures at slow speeds:
h. p. cut-off.
P=C^ 1. p. cut-off.
In this formula / is the absolute receiver pressure, />x
the absolute h. p. initial pressure, and c is a numerical co-
efficient.
An examination of a considerable number of indicator
cards from compound locomotives gave an average value
for c of 0.46, but this value is not recommended except for
approximations, and, of course, no such formula can take
the place of direct experiment.
26. Loss Due to Drop of Pressure in Receiver. — The
drop of pressure into the receiver, 25, represents an actual
loss of efficiency, since it occurs by the expansion of the
steam without doing useful work. For any given cut-off,
or position of the reverse lever in a locomotive, this drop
can be removed, but, in doing this, other losses or un-
satisfactory actions at other cut-offs may result, which
will make such removal of drop of receiver pressure at any
particular cut-off undesirable. A method of calculating
the drop in the receiver from elementary indicator cards,
but which does not represent actual conditions, is given in
Appendix E.
CHAPTER VI.
COMBINED INDICATOR CARDS AND WEIGHT OF STEAM
USED PER STROKE.
27. Combined Diagram Receiver Type. — It is quite
necessary, in order to understand where the losses are in
compound locomotives, to construct what is called a
" combined " indicator card, which is a diagram showing
r^ n
-dLLb-
O'
FIG. 23.
Combined Diagram from Two-Cylinder Receiver Compound.
the indicator cards from both h. p. and 1. p. cylinders,
drawn to the same scale and compared to a reference curve
in the matter of expansion. In this way the expansion of
the steam in the two cylinders is compared approximately
with equal expansion in a single expansion engine, 45—46 ;
however, the usefulness of such diagrams is limited, and,
48
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 49
.at the best, they only show the serious defects, and not the
minor ones.
28. The Rectangular Hyperbola as a Reference
•Curve. — The reference curve that is the most satisfactory
•of all to use is the rectangular hyperbola, 41, the method of
drawing which has been described in Fig. 3. Fig. 23
[illustrates a combined diagram from a two -cylinder
Deceiver compound locomotive, of which the separate cards
as taken closely resemble Fig. 19, card No. 4. In making
tthis combined diagram, the cards are drawn to the same
.scale of pressures and volume as follows :
Take any convenient distance, such as b c, to represent
rthe volume of the 1. p. cylinder, and let a b represent the
^volume of its clearance space. Then 0 a Pis the zero line
from which to measure volumes, and 0 V drawn as usual is
the zero line of pressures. Lay off a d equal to the h. p.
clearance space, and d e equal to the volume of the h. p.
cylinder, both on the same scale as that of the 1. p.
cylinder ; or d e should equal b c divided by the ratio of
the cylinders. The outlines of the cards are then found by
plotting points as usual.
The rectangular hyperbola, m n, for instance, is not a
curve that corresponds to equal steam weights at different
points, but to the contrary, rises above the curve of equal
.steam weights, and therefore approximates more nearly to
£he real curve of expansion in the simple engine than the
other curves of expansion sometimes used. See Fig. 23a.
This explanation is necessary in order to indicate why the
rectangular hyperbola is taken as the basis of such argu-
ment as is here offered about combined indicator diagrams.
It is evident that, at the point K' , the exhaust in the
1. p. cylinder, all of the steam is not sent in the 1. p.
-cylinder or receiver, but some of it is retained and is com-
pressed in the clearance spaces ; therefore, by calculating
;the amount of steam retained, say at q, we shall find a
COMPOUND LOCOMOTIVES.
-
N P"
6 B
2
to
etf
Q
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 51
substantial amount to be deducted from the amount at K' ,
in order to get the weight of steam that is discharged into
the receiver.
The actual weight of steam used per stroke is greater
than the apparent weight, for the reason that the 1 5 to 40
per cent, of the entering steam that is condensed before
cut-off is not re-evaporated during expansion, and the
steam at K' contains a large amount of water, 69-72.
29. Location of Rectangular Hyperbola for Refer-
ence.— The point from which the hyperbola m n should be
FIG. 23b.
Weight of Steam in Cylinder at Different Points of the Stroke.
drawn depends upon the purpose for which the examina-
tion is being conducted. Before further explanation of this,
it is necessary to understand how much steam is used in a
cylinder per stroke, and what should be expected of it in a
comparatively perfect engine, 41-44.
30. Weight of Steam Used per Stroke. — By means
of the total volume of the cylinder at any point, /£, Fig. 23,
which will be represented by/' k and from the pressure of
the steam represented by o' k, the total weight of the steam
in the cylinder at k can be calculated. This is true of
other points, k' k' ' and k' ' ' , also of q and R. In a single ex-
pansion engine it will be found, by calculation from an actual
52 COMPOUND LOCOMOTIVES.
indicator card, that the weight of steam increases from k to
k' ' ' almost uniformly, see Fig. 230, 42-44. This is due
to the re-evaporation during expansion of the steam that
was condensed before cut-off, due to the cooling effect of
the cylinder walls. The re-evaporation is caused by the
heating effect of the cylinder walls on the steam and water
in the cylinder. As the pressure falls during expansion, the
temperature of the steam falls, and the walls, being hotter
than the steam, re-evaporate some of the moisture in the
cylinder, 69-72,
We have seen that the steam sent to the 1. p. cylinder
from the h. p. is the difference between that at k' and q.
If none of this steam is lost in transit through the receiver
or in entering the 1. p. cylinder, it will be apparent in that
cylinder, and the difference between the steam at k' ' and
the steam at R should equal that sent from the h. p.
cylinder. Later on, at /£''', it should be expected that
further re-evaporation would make more steam apparent.
This can be learned from the difference between that at
k' ' ' and R than that between k' ' and R. This continued
re-evaporation in the 1. p. cylinder generally takes place,
and in a good compound locomotive, where the valves are
tight, it will be found that the steam present, as shown by
the indicator cards, will increase quite regularly from the
point k to the point k' ' ', when allowance is made for the
steam retained in the h. p. cylinder at q, 44
31. Weight of Steam Retained in Cylinder at End
of Compression. — In assuming or locating the points q
and R, much care should be taken, as the amount of steam
in the cylinders, shown by the indicator cards, decreases
continually from the time the exhaust closes, which is the
commencement of compression, to the opening of the valve
for pre-admission due to lead, 6. The point q should be
taken to represent, as nearly as possible, the weight of
steam in the cylinder when the valve opens, and, there-
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 53
fore, it should be taken well up on the compression line,
and as near to the point of admission as possible. This is
also true of the point R. Fig. 2$b further illustrates this,
and shows the change in apparent steam weight during
compression. See Fig. 4.
It is clear that if the valves of a compound engine are
tight, the same amount of water, in the shape of moisture,
steam and water, must be discharged from the h. p. as from
the 1. p. cylinder at each stroke ; otherwise, if the 1. p. dis-
charged more than the h. p. the receiver would be quickly
emptied, or if less than the h. p. it would be quickly filled
with water and steam, 44. All this adjusts itself automatic-
ally, and the pressure in the receiver rises and falls as the
cut-offs in the cylinders are changed in such a way as to bring
about the same discharge of water, in the shape of steam
and moisture, from the 1. p. cylinder as is discharged from
the h. p. cylinder into the receiver.
32. Limitations of Combined Diagrams. — In making
an examination of the action of an engine, by means of
the combined diagram, it must not be forgotten that such
diagrams have a distinct limitation, which is found in the
fact that they show only the steam in the cylinder and,
therefore, only the apparent amount of water, and do
not show the moisture or water in the cylinder, which
must be added to the apparent amount of water, in the
shape of steam, in order to get the actual total water
used per stroke, 69-72. In other words, there is a con-
siderable amount of water passing through the cylinders
of the compound engine, in the shape of moisture in the
steam, which is not measured, indicated or made appar-
ent by the indicator cards, 69. However, this limitation of
the value of combined diagrams does not prevent them
from being decidedly useful when such limitation is under-
stood and allowed for, as will appear from what follows :
54 COMPOUND LOCOMOTIVES
33. Re-evaporation in Receiver. — If in a compound
receiver engine it is found by calculation from the indicator
cards, 30, 72, that more apparent water, in the shape of
steam, is used per stroke in the 1. p. cylinder than in the
h. p., then one may be led to understand that there is
either a leakage in the valves or a re-evaporation (not
super-heating) in the receiver.
Super-heating in the receiver of a compound locomotive
is practically impossible, unless the smoke box temperature
is above what it should be for good economy in the boiler,
for the reason that the steam passes through the receiver
when the engine is at speed at a rate that would make it
impossible to collect enough heat to re-evaporate all of the
moisture in the steam, much less to cause a super-heat,
54-55. This has been shown by tests made by Mr.
William Forsyth, Mechanical Engineer, of the Chicago,
Burlington and Quincy Railroad, on a two-cylinder com-
pound locomotive having a receiver in the smoke box.
1 1 is true that the temperature of the smoke box is about 600
degrees Fahrenheit, quite sufficient to produce a substantial
super-heat, if the steam remained in the receiver long enough
to permit it ; but at 200 revolutions per minute, which is an
ordinary velocity for a locomotive, there are 400 exhausts
into the receiver per minute. If the receiver is about twice
the volume of the 1. p. cylinder up to cut-off, then each
cubic foot of steam remains in the receiver about Yinr Pai"t
of a minute, or about ^ of a second, a much too short time
to permit of super-heat.
34. Condensation in Receiver. — On the other hand,
if it is found that less steam is apparently used in the 1. p.
cylinder than is discharged into it from the h. p. cylinder
per stroke, then it may be expected that there is a loss' of
steam by condensation in the receiver or in the 1. p.
cylinder, 54—55. Some results of calculation of this kind
are given in Table J. 30, 72.
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 55
In this way an examination can be made to learn if the
steam at k' ' , Fig. 23, less that at R, is greater than that at
k' ' , less that at q. This will indicate whether there is a gain
or loss up to cut-off in the 1. p. cylinder. Allowance should,
of course, always be made for the steam at q and R, as the
steam at R always mixes with the incoming steam from the
h. p. cylinder. To be still more accurate, the difference in
the heat contained per pound of the steam at R, q, k' ' , and
k' , should be allowed for.
35. What is Shown by Reference Curve on Com-
bined Diagrams. — It now will be clear that in drawing the
rectangular hyperbola m n, it may be drawn from the point
k to note the re-evaporation at k' , or from some point, as m,
located so that the volume P m corresponds to the volume
of the weight of the steam, which is discharged into the
1. p. cylinder at each stroke. Manifestly, when the curve
m n is located in this way, it will fall to the left of k' , Fig.
23, and if there is no loss between the cylinders and up to
cut-off in the 1. p. cylinder, it will pass just to the left of
point k' ' and inside of the expansion curve of the 1. p.
cylinder by an amount which depends upon the steam that
is added to the incoming steam from the h. p. cylinder,
from the compression or clearance spaces in the 1. p.
cylinder. This last amount is that which is calculated for
the point R. This is further explained in the analysis of
the combined diagrams from the four-cylinder non-receiver
type, 41-44.
36. Ideal Combined Diagram. — To show what the
ideal combined indicator card would be from a compound,
reference is made to Fig. 24. This card was taken
from a triple expansion Corliss pumping engine running
at twenty revolutions per minute. The cylinders were
5 feet stroke, and with the following diameters: H. p.
cylinder, 28 inches ; intermediate cylinder, 48 inches ;
1. p. cylinder, 74 inches. Careful tests of this engine
56 COMPOUND LOCOMOTIVES.
showed a consumption of twelve pounds water per horse-
power per hour. There is little, if any, loss of steam by the
drop in the receiver, and practically no loss from com-
pression and wire-drawing. Compound locomotives cannot
be made to give cards like this, even at the slowest speed,,
for the reason that the locomotive has to be designed to
work at different cut-offs, while the stationary compound is
made principally for a single cut-off, or with very small
variations therefrom. However, a comparison of this
card with an actual indicator card, Fig. 25, will show
where the loss occurs in the compound locomotive at the
FIG. 24.
Ideal Combined Card.
present time, and further explains why high speed com-
pound locomotives have not given the economy that they
should, 139-147.
The upper cards A and B of this diagram, Fig. 24, rep-
resent probably the best steam distribution that has been
obtained from a two-cylinder receiver compound. Taking
the area of these cards A and B and calculating the horse
power, omitting the 1. p. card C, and taking the same total
water per hour that was actually used in the test, the water
per horse power is found to be 18 pounds. That is to say,
wrhile the water per horse power per hour with the triple
expansion engine, giving cards A, B and C, is 12 pounds,
yet by omitting the work done by card C, to bring the
result more nearly like a two-cylinder compound locomo-
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 57
tive,. the resulting water per horse power per hour is about
1 8 pounds. It may be said then that a compound locomo-
tive must use steam with approximately as good distribution
as shown by Fig. 24, in order to reach as low a water rate
as 1 8 pounds per horse power per hour. However, the
steam pressure on a locomotive is generally higher, say 180
pounds per square inch, while in the case of Fig. 24 the
steam pressure was but 120 pounds. On the other hand,
the triple expansion engine had steam jackets and other
advantages which would tend to offset the advantage of
higher boiler pressure.
FIG. 25.
Actual Combined Card.
37. Combined Diagram from Non- Receiver or
Woolf Type. — Combined diagrams from the Woolf type
of compound having no receiver, sometimes called " con-
tinuous expansion " compounds, differ greatly in appear-
ance from those of receiver compounds, 27—32, as will
appear from Figs. 23 and 26. The following is an analysis
of Fig. 26, which will emphasize what has been said about
steam use for Fig. 23. The cards in Fig. 26 have been
combined on a new plan, which shows the effect of
clearance in the cylinders and valves. The line ZC' ' is.
58 COMPOUND LOCOMOTIVES,
the line of zero pressure. The line of atmospheric pressure
is just above it. The mean effective pressures and the
clearances of the engine are given on the diagram. The
indicator cards, shown on the left hand part of the diagram,
are an exact reproduction of the ones taken from the
engine. The indicator diagram on the right side shows the
1. p. diagram enlarged, so that the pressure at each
individual point of the diagram is plotted on a volume
exactly equal to the volume which the steam occupied in
the 1. p. cylinder when it had a corresponding pressure.
For instance, take, the point K on the 1. p. diagram, the
pressure represented by G' K is exactly that which was
in the 1. p. cylinder at admission, and is equal to F' Y,
while the volume which is represented by the distance 0 G' ,
is exactly the volume which the steam occupied in the
cylinders when it has the pressure, G' K, and this is true
of every other point on the expansion line of the combined
diagram.
38. Method of Combining Indicator Cards from
Non-Receiver Type. — The method of combining the
diagrams is as follows :
From 0, which is the point of zero volume, the distance
0 C' is laid off equal to the h. p. clearance. C' F' is the
length of the indicator card as taken. F' P' corresponds
to the volume of the space in the valve between the h. p.
and the 1. p. cylinders. P! G' corresponds to the clearance
in the 1. p. cylinder. OC" corresponds to the volume of
the 1. p. cylinder (being about 2.93 times the volume of the
h. p. cylinder), plus the 1. p. clearance. Between the
vertical lines drawn from C' F' the actual indicator card
is laid out.
The line K H is the expansion line in the 1. p. cylinder
taken from the actual indicator card, and the pressure at
every point on this expansion line is plotted at a volume
point exactly corresponding to the volume of the steam in
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 59
the cylinders, as shown by the actual indicator cards. At
the point //, which is the cut-off in the 1. p. cylinder, the
volume is reduced by the amount HJ, which is the sum of
the volume of the interior of the valve, or R Q, and the
volume remaining in the h. p. cylinder and the volume of
h. p. cylinder clearance together, or V U. Thus the volume
occupied by the steam after cut-off is represented by the
distance 0 M' , and the pressure corresponding to that
volume is M' J.
After cut-off the steam expands from the point /, as
shown by the line//', and this line corresponds with the
expansion line on the actual indicator card ; that is, at each
point the pressure is plotted on a volume corresponding to
the actual volume occupied by the steam.
This method of plotting is necessary in order that a
comparison may be made between the lines EE' -££" -DD'
and D D" , which are theoretical lines drawn to show any
peculiarities of the expansion of the steam in the two
cylinders, 43. Without this method of plotting no fair
comparison could be made, as the pressure would not be
plotted on actual volumes, and a false and untrue condition
would be exhibited.
The over-lapping of the 1. p. indicator card from H to
J is necessary by reason of the abrupt reduction in the
volume occupied by the steam at cut-off in the 1. p. cylinder,
the reduction being caused by the cutting out of the volume
of the valve and the volume yet remaining before the com-
pletion of the stroke of the h. p. cylinder. In order that
the true area of the combined indicator card may be pre-
served, it has been found convenient to draw the dotted
sections R Q P S and V U T W, which are together equiv-
alent to JIN M. This makes the mean effective pressure
determined from the entire area of the combined indicator
cards, including the dotted section, exactly the same as
that determined from the original cards.
6o
COMPOUND LOCOMOTIVES.
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 6 I
The pressure during exhaust and compression on the
combined diagram is plotted at the same point as the cor-
responding pressure in the steam line of the actual card ;
that is to say, the back pressure at N is the one correspond-
ing to the back pressure on the point below the cut-off
point on the original indicator card. That is, the pressure
at N is the same as the pressure at U, just as the pressure
at H is the same as the pressure at T. This is an unim-
portant fact, however, as the combined diagram is mainly
drawn for the purpose of examining the correspondence
between the theoretical expansion line and the actual ex-
pansion line of the steam in the cylinders, and not to get
the mean effective pressures. By these lines are shown the
continual re-evaporation and corresponding increase in ap-
parent steam weight during expansion in the h. p. cylinder.
At the point 3 the h. p. cylinder exhausts into the valve and
into the 1. p. cylinder clearance. Here it meets with steam
that was retained in the valve at cut-off at the point H or
T in the 1. p. cylinder, and with steam that was left in 1. p.
cylinder clearance after compression, and therefore the
total steam weight is increased.
If no steam leaked out of the valve or condensed from
the time it was shut in at cut-off in the 1. p. cylinder, and
none of the steam was condensed or lost from the clearance
spaces after compression in the 1. p. cylinder, the total
steam weight at the point K would be the sum of the steam
exhausted from the h. p. cylinder, the steam that was left
in the valve, and the steam remaining in the 1. p. clearance.
39. Losses Shown by Combined Diagram from
Non-Receiver Type. — If there were no losses, and making
due allowance for the lower pressure arid temperature of
the steam in the valve and in the 1. p. clearance, the pres-
sure at K, Fig. 26, should be 101 pounds absolute instead
of 92 pounds. The weight of the steam in the valve and
in the 1. p. clearance, which would be mixed with the steam
62 COMPOUND LOCOMOTIVES.
from the h. p. cylinder, at exhaust from the h. p. cylinder
is about 21 y2 per cent, of the weight exhausted from the
h. p. cylinder, provided there was no loss of any kind from
the clearance of the 1. p. cylinder and the clearance in the
valve after the steam wras shut into these cavities. The
point G shows what the pressure would be if there was no
loss. If all the steam shut in was lost, then the point K
would fall about to the point Y'. The tighter the valve
and the less the loss in other ways of the steam that is shut
in, the higher the point A" will be above the point Y'. It
has been said that the rise of pressure at the point K above
Y' shows leakage, but this is a mistake, unless all the
steam shut into the valve and into the 1. p. clearance is
assumed to be lost. That this steam is not wholly lost is
shown by the fact that the point K does actually rise con-
siderably above the point Y'.
As we go on with this analysis to the pomt of cut-off,
or at //, we find that the weight of steam in the cylinders,
as shown by the indicator card, increases continuously and
according to the following numbers :
Weight at K, .66 pounds ; and at other points, .66, .68
and at the point H .70 pounds. At this point the volume
is decreased by H J, and steam at the pressure H is shut
into the valve and the h. p. cylinder, and the total apparent
steam weight is decreased, as shown by the actual indicator
card, to .575 pounds, the pressure, of course, remaining
the same as at H.
In the case of this particular indicator card, it is curious
to note that the point / falls upon the hyperbola E Y'
E' drawn from the h. p. indicator card expansion line, and
indicates that, up to the point of cut-off in the 1. p.
cylinder, there has not been leakage enough or re-evapora-
tion enough to raise the steam pressure above the hyperbola
drawn from the expansion line of the h. p. indicator card.
Also it is a curious fact that in this particular indicator
COMBINED INDICATOR CARDS — WEIGHT OF STEAM. 63
card the expansion line in the 1 p. cylinder after cut-off, as
shown by / /, corresponds almost exactly with the hyperbola
E E' , just described. This shows that while at the point of
the exhaust from the h. p. cylinder a considerable amount
of steam is added to that exhaust (from the interior of the
valve and from the 1. p. clearance), yet this added steam
is not wholly lost, but part is returned again to the valve and
h. p. cylinder at the point of cut-off in the 1. p. cylinder.
As has been said before, 28, the hyperbola corresponds
more nearly to the actual expansion line of steam in a
locomotive cylinder than does the adiabatic, owing to the
re-evaporation of the steam that was condensed up to
the point of cut-off. Therefore, if the pointy on any com-
bined indicator card should fail much below the hyperbola
E E' , one would suspect considerable loss due to condensa-
tion ; and if it should' rise very much above this hyperbola,
one would suspect leakage or an unusual amount of re-
evaporation, but more probably leakage.
40. Correct Area of Combined Diagram Non-
Receiver Type. — In measuring the area of this combined
indicator card, one must follow the lines K H IE" N M L
K. This will appear from a study of the way in which the
card is laid out. This method of combining cards is ex-
ceedingly simple and can be followed without incon-
venience. To do it one needs only to calculate the volume
occupied by the steam at several points and plot these vol-
umes from 0 as an origin.
41. Reference Curve for Combined Diagram Non-
Receiver Type. — The proper theoretical line to be drawn
for comparison on a combined indicator card is a matter of
some dispute, but as each line has its own particular value
and meaning, there is not much to dispute about, 43. The
point from which the theoretical line should be drawn is of
more importance.
In a single expansion engine with tight valves, the total
64 COMPOUND LOCOMOTIVES.
.amount of water in the shape of steam and moisture in the
cylinder does not change after cut-off until exhaust is
reached. Some of the steam may be condensed, but the
total water remains the same. With compound engines, of
the non-receiver type, however, this is not so, for the reason
that at cut-off in the h. p. cylinder and at the closure of the
exhaust from the h. p. cylinder, a considerable amount of
: steam is retained in the valve and clearance of the h. p.
cylinder. The steam used per stroke in the h. p. cylinder,
as apparent from the indicator card, is the difference between
the amount present in the cylinder at the point 3, Fig. 26 ;
and the amount retained in the cylinder during compression,
.taken for example at the point 4. For one to draw the
theoretical steam line from the point 3 is to assume that all
the steam that enters the h. p. cylinder during admission is
exhausted therefrom, but this is not true. The real amount
is the difference just referred to, and is represented by the
volume B D, B E being the amount admitted to the h. p.
cylinder; so that to look for leakage or re-evaporation in
the 1. p. cylinder after cut-off, the theoretical steam line
should be drawn from the point D, and not from the
point E,
42. Weight of Steam per Stroke. — It may not be
clear why this is so without further explanation. In any
compound engine as much water in the shape of steam or
moisture must pass out of the 1. p. cylinder as is passed out
of the h. p. cylinder ; otherwise, there will be a collection
of water in the 1. p. cylinder which would go on until the
cylinders were full. That is, the amount of water in the
shape of steam taken from the boiler at each stroke of the
h. p. cylinder must be the same as that thrown out from
the 1. p. cylinder at each stroke.
If the volume B D and pressure at D indicates the
amount of steam given from the h. p. cylinder to the 1. p.
,at each stroke, then this amount should be looked for after
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 65
the cut-off in the 1. p. cylinder, barring, of course, all gains
due to re- evaporation of the moisture in the steam and the
losses due to any condensation, 69, that may take place.
This leads to the conclusion that in an examination of the
steam lines on the combined card from E to H (H being
the point of cut-off in the 1. p. cylinder, and also the point
of the commencement of compression in the h. p. cylinder),
the theoretical expansion line should be drawn from the
point E and for the examination of the steam pressures after
cut-off in the 1. p. cylinder, that is, from /to the end of the
stroke, the theoretical steam line should be drawn from the
point D. It follows, then, that to determine, by compari-
son of pressures at the end of the expansion of steam in
the two cylinders, the leakage, re-evaporation, or con-
densation, during the passage of the steam through the
cylinders, the theoretical steam line should be drawn from
the point D and the comparisons should be made after
cut-off in thel. p. cylinders. This is because any leakage,
re-evaporation, or condensation, will show up most prom-
inently after the cut-off point/, Fig. 26.
43. Other Reference Curves for Combined Dia-
grams.— In this particular diagram both the hyperbola
and the adiabatic lines have been drawn from both points
E and D. E E' and D D' are hyperbolas, E E" and D
D" are adiabatic curves. It will be seen that the point /
rises considerably above the adiabatic curve drawn from D,
and this shows either some leakage or re-evaporation. It
also falls somewhat above the hyperbola from the point D.
This is a further indication of leakage or re-evaporation ;
but there is and should be in every engine a considerable
amount of re-evaporation, which will frequently raise the
actual steam line above the hyperbola. Therefore, so far
as this combined diagram shows, there is no strong evidence
of leakage. However, the combined diagram is not the
best way to show leakage. It is a good graphical way of
66
COMPOUND LOCOMOTIVES.
showing how the volume, pressure and weight of steam
changes during the entire expansion of the steam, but it is
not as accurate in showing leakage or re-evaporation as the
comparison of the steam weights. See Appendix O.
44. Weight of Steam per Stroke, Various Com-
pound Locomotives. — Take this particular card and refer
to Table J, Card No. 3, C. B. & Q. tests. It will be seen
that the card shows that .507 pounds of steam was used per
stroke in the h. p. cylinder and .493 pounds used per stroke
in the 1. p. cylinder. These amounts are practically the
same, and, so far as the indicator card goes, there is no
evidence of more steam being thrown out of the 1. p.
TABLE J.
Giving the Weight of Steam Used per Stroke in Several Compound Locomo-
tives. This Data was Calculated from Sample Indicator Cards.
S
g «U
Jc ci
c"o A
d.
•E
c3
a
4) O
"IS
u o
•St:
£ c
.5° •
£ c
"° «
^^ js _;
*' g «
Engine.
o
C U
° aE-
1 a"&
si
£e
a «
g w
c
« o.'S
rt
*a 3
.c
« «
8
^ S
fc^ W! •
rt rt •
os oj
*? •" rL
1
JN
?"
1^
J3°fr
Q^"
^His^
(gSS&
§**
51
121.4
.4999
.5026
.0027
0.5
67
Baldwin No. 82 in
C., B. & Q. tests.
48
8
3
140.1
210.2
I40.I
.5000
.3428
•5071
•4931
.3650
.4908
.0222
.0069
.0163
"6.'5"
1.4
3.2
g
33
186.8
.3780
.4052
.0272
7-2
58
i
120
.4568
•4451
.0117
2-5
58
Baldwin No. 82 in
Erie tests.
2
3
4
160
160
140
.4320
.4293
•3499
•4452
.4007
'3564
.0132
.0065
'.0286
3.0
1.9
' ' '6.6 ' '
48
5
172
.3605
.3681
.0076
2.1
52
Schenectady, 12
Wheeler,
2&2a
6&6a
15°
156
1 80
.8022
I-J374
•7I03
1.0646
.0919
.0928
11.46
8.02
44
66
Eng. No. 367.
8&8a
192
.9518
•8579
•°939
9.86
Schenectady, 10
61
100
.7920
.7144
.0776
9.80
59
Wheeler,
74
152
.7028
-6363
.0665
9.46
59
Mich. Cent.
80
124
.8247
•7259
.0988
11.98
59
C., B. & Q. Mogul,
Eng. No. 324.
8
49
243.9
.5861
.4932
.6631
.6001
.0770
.1069
21.6
::::::::
35
Rhode Island Comp.
on Brooklyn Ele-
27
1 80
006
.2765
.2639
.0126
4.0
86
64.
vated.
Great Eastern Wors-
3
252
.5110
.4586
.0524
10.
42
dell Comp., Eng.
4
192
•4992
.4609
-0383
7-7
57
No. 230.
5
264
.3918
•3390
.0528
13-5
48
X
72
•593°
.6918
.0988
16.6
69
TVIpvi n (~*pnf«.o1
60
6611
0664
Johnstone Comp.
3
57
•6344
.7140
.0796
12.5
79
4
66
•5887
•6399
.0512
8-7
70
COMBINED INDICATOR CARDS WEIGHT OF STEAM. 6/
cylinder than is thrown out of the h. p. cylinder, which
would be the case if there was any considerable leakage
through the piston valve. In making these analyses one
must remember that there is a large amount, something
over 30 per cent., of water present in the steam at the point
of cut-off in the h. p. cylinder, and the major part of this
water goes through the engines without being shown on
the indicator card. It is this water which re-evaporates
and raises the steam line at cut-off in the 1. p. cylinder
above the adiabatic curve. We have seen that in this card
there is no more steam used by the 1. p. cylinder than by
the h. p., but this is also true of other cards from this and
other engines of the same type, as shown by Table J.
As the pressure of the steam decreases during expansion
there is a continual increase in apparent weight from the
indicator cards.
If the rate of re-evaporation in the h. p. cylinder (if
such it be and not leakage, and it probably is re-evapo-
ration, as there is no reason to believe that steam would
not re-evaporate in this type of h. p. cylinder just as in
any other h. p. cylinder) be continued until the commence-
ment of the stroke of the 1. p. cylinder, the weight of
steam at K, Fig. 26, would correspond to the actual appar-
ent weight from the indicator card. But it is not to be
expected that this rate of re-evaporation would thus con-
tinue, owing to the fact that the steam when it is dis-
charged from the h. p. cylinder meets comparatively cold
surfaces and intermingles with steam in the valve and in
the 1. p. clearance which is of a lower temperature. Of
course this last argument is mainly a speculation, and is
interesting only so far as speculation goes. It is a curious
fact, however, that assuming the rate of re-evaporation to
continue, the calculated weight of the steam shut into the
valve and 1. p. clearance would raise the pressure to G" at
the commencement of the stroke of the 1. p. cylinder, and
Of THB -
WVBBSXTY
68 COMPOUND LOCOMOTIVES.
the loss would have been G" K, but that it is impossible
that this was the case is clearly seen from an analysis
of the steam weight at different points of the indicator
card. To claim that the valve, at the time of admission to
the 1. p. cylinder, is filled to the same pressure as the pres-
sure of the exhaust from the h. p. cylinder, as has been
claimed, is to admit that the area represented by G" K H
H' is wholly lost. But it is easily shown that this is not
the case. <
The indicator card, Fig. 26, shows that about 17.4
pounds of steam were used per horse-power per hour. Of
course this does not account for the loss due to condensa-
tion up to cut-off. From the actual tests an approximate
estimate of the water used per horse-power per hour is 29.9
pounds, leaving 10.5 pounds of water per horse-power per
hour not shown by the indicator card, the measurements
being taken just after cut-off in the h. p. cylinder. This
indicates a condensation of about 37 per cent, of the steam
entering the h. p. cylinder up to cut-off. The insufficient
data from which this result is obtained renders it probable
that the 37 per cent, is not the correct amount. It may be
more, but it is probably less. This, of course, is only
another speculation and interesting only so far as specu-
lations go. However, the plan of analysis indicates what
can be done when a complete set of data is furnished.
Whether this data can be collected from a road test is
somewhat uncertain, but it surely can be collected from a
shop test, such as is now made regularly at the Purdue
University by Professor Goss, who has a large Schenectady
single-expansion eight-wheel locomotive mounted on carry-
ing wheels and operated with as much power as the same
engine would exert if it were hauling a regular train. The
advantage of this arrangement is that very accurate
measurements can be made of the water and fuel used.
It also permits accurate indicator cards to be taken.
CHAPTER VII.
TOTAL EXPANSION. RATIO OF CYLINDERS.
45. Total Expansion from Elementary Indicator
Cards. — It is frequently necessary, for the purpose of
comparing the action of locomotives, to know the total
expansion of the steam in each type, and while it might
appear from Figs. I and 2, 2—3, that this can be done by
reasoning from the known volumes of the cylinders and
points of cut-off, yet in fact the steam use is so affected by
wire-drawing and compression that calculation is of little or
no value, 12-19. The only accurate way to get the total
expansion is to examine the actual indicator cards, from
a locomotive that has been built, or the pre-determined indi-
cator cards of a proposed design. These pre-determined
cards should always be made up from cards from existing en-
gines of similar design, with such corrections as experience
or judgment show to be necessary to include the differences
between the proposed and actual locomotives. An approxi-
mate method of calculating the total expansion from the
elementary indicator card is given in Appendix D.
46. Total Expansion from Actual Indicator Cards.—
The difference which is generally found between the theo-
retical* total expansion and the actual total expansion in
practice is sh®wn by Table K.
Table K, taken from same data as Tables B, C, D, E, F,
and G, shows the difference in the ratios of expansion in the
individual cylinders and the total in both cylinders when
estimated by different rules commonly used, and illustrates
*" Theoretical " as here used is intended to be understood as applying to the limited theory
of steam expansion commonly used as a basis for the computation of mean effective pressures.
See Chapter I.
69
COMPOUND LOCOMOTIVES.
•i|
,s s
*
I-H uapuijXD -d •[ uoisusdxa
<! jo pua JE aJnssa-id ajrqosqv
u-)U->O\O O O^nf^r^)
uOiOrf'^-OOfOM CM M
•japuijXo -d -q uois
O t^I>.TfCM u->u-)VOO
O LOOO X^l->I^.t^OiO
siuipE JE ains. ajrqosqy
•ui -bs
>H jad spunoj Maputo -d -\ ui
uoisuudxa jo pua }E aanssaaj
O O rfi-r>u^u-)OOO!X)
rj- TJ- rn M HH M M
•paaaptsuoD s; uo-jno
JEnjDE JOU pUE '}U3.IEddE UaqM
UOISUEdxa }U3JEddE J3}E3J3
,, ai{i pus sissq s;qj jo aojja
^ aq; 3uiA\oqs 'saapuiiXo jo OIJEJ
QO t^SO O rf "Jj- 04 M M
Tf 1000 CO O O SO OO 00
pus aapuqXo -d «q ui jjo-jno
lusjsddE uo pasEq sjaputjAo
qjoq uoisuEdxa jo OIJEJ IEJOJ^
^ juajEddB uo passq aapuqXo
I-H c^ c^iocNOCDrorr;
•d *q ui uoisuEdxa jo opE'jj
_ii_rtMt-(MC4(NCS
'iz si qoiqAV
saapuijXD jo OIJEJ pus •£) '{03
, jo pn'poid Supg 'suapuiiAo jo
Tf 10
"3-mr^oioo CN ^ CM
-jno JEHJOE uo pasEq sjapuijA?
q;oq uoisuEdxa jo opBJ JEJOJ^
•saapui^D qjoq ui jo
^ -}iio JBUJDE uo pasEq uoisuEdxa
^ JEJOJ sqj 3AoqE uoisuEdxa JEJOJ
jEnjoE jo asEaaout jo "juao aa^
TT M 10 O tl-QO Tf HH t>»
OOOCNOOOi-ii-i
CM(N<NwMCM>-HMCN
•sajnssaad JEIJIUI o;
r_^ IEUIUU9} JO OIJBJ 3upg 'SpJBD
•• JOlEDIpUl UIOIJ p3JnSE3UI UOIS
-usdxa jo OIJEJ JEJOJ |Bnpy
>-O
o oo ^r M t^oo o o oo
•uo-;na
C/3 JEUJOE uo pasBq saapuqAo
rONvO-OGOGO O O O
ro ^J-O O t^ t^\O O O
qjoq uoisuEdxa jo OIJBJ IBJOJ^
MMMMNCSfOcnco
•UO-4HD
p^ jBmoE uo pasEq aapuijXo
""lO^f^ONNwMiH
I-H HH CM ^^O <O OO OO OO
•d •[ uoisuEdxa jo oi}Ey;
•uo-jno
O^EnjDE uo pasEq aapuijAD
O O\ M t^ i-i w O\C\O\
1-1 I-H r^rrt^t^OOON
•d -q uoisuBdxa jo opEy;
%
(X
OOOOOOO lOLOLOlOiO
J
O CMOOOOOOO M H-I >-H
OOOO t^.O IOU~1»OIO>O
iocs o low 1-1 r^t^r^
w
^(-MfOrOCMeMCM^CM
oooo i>.o LoiOTj-Trrr
AH
•JU30 J3d '30UEJE3|0 ^
COCMiOCMOO >-i 1-1 M
l^.rJ-OO 1-1 1-1 1-1 wiioin
oooo r^r^oo xoiovo
U3uipnpui uo-jno pmoy ^
a
•rTOO O M Tf Tf- CM CM M
o roo oo oo oo o o o
oooo r^o io<-o«oio>o
•jaquiux PJB0
-i CM r^Tl-voO t^CO O
TOTAL EXPANSION RATIO OF CYLINDERS. 71
the variation in the results given by these rules, and
emphasizes the need of a perfect understanding of the wide
difference between the theoretical and practical operation
of compound locomotives
The important fact is shown that the ratio of the initial
and final volumes in nowise indicates the real ratio of ex-
pansion. This results from the effect of the comparatively
small receivers used, which gives a large drop in pressure
in the receiver, 25-26, and the wire-drawing due to in-
adequate valve motion. . This more particularly applies to
the conditions when the engine is running at considerable
speed, for at such times the reduction of pressure due to
wire-drawing is equal to or greater than the reduction
resulting from expansion. This shows how a compound
locomotive at high speed may approach more nearly to a
throttle-governed wire-drawing steam engine than to one
having a variable cut-off. It is this action which reduces
so greatly the otherwise possible saving of a compound
locomotive at high speed, 139-147, and when taken to-
gether with losses resulting from compression gives nearly
a full explanation of the reasons why a majority of com-
pound locomotives, thus far, have not shown a very sub-
stantial saving in passenger service.
Note. — The terminal pressure for Table K is not taken
as that at exhaust, but is taken at an equated pressure lying
between that at exhaust and that at the end of the stroke.
This is done to allow for the useful work done by the steam
during exhaust before the end of the stroke is reached.
The equated terminal pressure thus taken is not an arith-
metical mean of the pressure at exhaust and the pressure
at the end of the stroke, but is so selected as to allow for
the work done from the exhaust point to the end of the
stroke. For the slow-speed cards it is taken nearly at the
exhaust point, and for the high-speed cards nearly at the
end of the stroke.
72 COMPOUND LOCOMOTIVES.
47. Ratio of Cylinders — Elementary Formulas
for. — In treatises on compound engines, formulas have
been deduced for the ratio of the volumes of the cylinders
so that the total work, 22, done by the engine will be
almost equally divided between the cylinders, 15, but such
formulas are not applicable to engines having much com-
pression and wire-drawing, and therefore not to loco-
motives. Usually for engines with receivers, these formulas
are based upon a constant receiver pressure. A rule that
has been frequently used is that the ratio of the volumes of
the two cylinders should equal the square root of the total
number of expansions desired. This rule will not apply to
locomotives.
48. Ratio of Cylinders as Affected by Maximum
Width of Locomotive. — So far as economy alone is con-
cerned, the maximum over-all-width of a locomotive and
the necessity for a minimum weight of reciprocating parts
places such a low maximum limit upon the diameter of the
1. p. cylinder of a two-cylinder receiver compound locomotive:
that it cannot always be given a volume that will give
the best theoretical economy ; however, single expansion
locomotives frequently work' with such low efficiency
that a compound can generally be given sufficient vol-
ume in the 1. p. cylinder to enable it to show a substantial
saving, although not the maximum saving that would be
possible under other and more favorable conditions. The
loss due to existing types of valve motion is so great that
the comparatively minor loss incident to a reasonable limi-
tation of the diameter of the 1. p. cylinder practically disap-
pears in comparison. With the four-cylinder compound, it
is possible to get a more economical volume of 1. p. cylin-
der, but it would appear from what has been done so far
that the four-cylinder compound introduces further troubles
in the valve motion, and the saving that would otherwise be
found, by reason of the larger 1. p. cylinder, is to some
TOTAL EXPANSION RATIOS OF CYLINDERS. 73
extent counterbalanced by a decrease in the efficiency of
the valve motion. This more particularly applies to high
speed locomotives.
It should be mentioned here that the use of a double
1. p. cylinder, as originally proposed by Mallet, 112, see
Figs. 28 and 100, will give a sufficiently large 1. p. cylinder
capacity to any compound locomotive of the two-cylinder
type, 51.
The term " valve motion," as here used, refers to sizes
of ports and all parts of the steam regulating gear.
49. Ratios of Cylinders Commonly Used. — The
cylinder ratios, which have been used for two-cylinder com-
pounds, range from 2.74 foi small engines to 1.77 for large
engines. Four-cylinder engines generally have a ratio of
about 3. Mr. Mallet, from his wide experience, has said
that the ratio for two-cylinder engines should not be less
than 2. Mr. von Borries recommends ratios of 2 for freight
locomotives and 2.25 for passenger locomotives. Ratios
between the limits of 2, and 2.2 have been adopted by the
majority of designers. For two-cylinder compounds in the
United States a ratio of 2.1 has been more generally used.
The foregoing gives prevailing practice.
As has been shown, mathematical calculation is not of
much value in determining the cylinder ratios, when such
calculation is based upon the elementary engine. It has
also been shown that the relative mean effective pressures
in the cylinders is more dependent upon the valve arrange-
ment at the present time than upon the sizes of the cylin-
ders, and, therefore, as the power in the cylinders depends
upon the mean effective pressure, it follows that the
division of power between the cylinders depends not so
much on the sizes of the cylinders as upon the action of
the valve motion and the size of the steam passages. And,
further, the necessity for starting trains quickly is such a
controlling condition that the ratio of the cylinder volumes
74 COMPOUND LOCOMOTIVES.
must be made, not what is most efficient from an economical
stand-point, but rather what will give a reasonably uniform
power at starting, and sufficient power on the h. p. side to
enable the engine to start without pulsations and jerks.
It is evident that the best practical ratio of cylinder
volumes must have been originally determined by experi-
ment. Experiments in cylinder ratios have been made
by nearly all who have undertaken to introduce two-
cylinder compounds, and many have traveled over the
ground of investigation covered by others, with the hope of
getting a satisfactory starting power and an even power dis-
tribution with better theoretical conditions for economy In
a recent case of this kind, the locomotive builder had to take
off the h. p. cylinder and replace it with a larger one. The
ratio at first was about 3, and it was finally made about
2.2 to i.
To emphasize and explain what has been sa d regarding
the incidental control of the mean effective pressures in the
h. p. and 1. p. cylinders by the wire-drawing and compression,
reference is now made again to Figs. 14 and 15, Cards I
to 9. See also Tables C, D, E, F, G, H, and I. These cards
represent about the best that has been done in the way of
an equal distribution of power between the h. p. and 1. p.
cylinders of large two-cylinder compound locomotives.
50. Ratio of Cylinders as Affecting Equalization of
Power in Two -Cylinder Receiver Compounds. — Theo-
retical investigation has had but little to do with develop-
ing the proper ratio, but practical experiment has shown
definitely that a ratio of 2.4 is as great as can satisfactorily
be used in a two-cylinder compound, and that a ratio of 2
is better, as it makes easier the approximately equal dis-
tribution of power between the cylinders at different speeds
and gives better results in starting heavy trains. It is a
simple matter to adjust the equalization of the power in the
cylinders of a two -cylinder receiver compound with a
TOTAL EXPANSION RATIO OF CYLINDERS. 75
volume ratio of 2 when the valve motion is good. It is
easier to accomplish this equalization with a ratio of 2 than
with a ratio of 2.4. With a ratio of 2.4 it is practically
impossible to equalize the power between the cylinders at
high speed, unless the ports and passages are unusually
large and the valve motion most excellent.
All things considered, it is better to assume the ratio of
volumes of cylinders for two-cylinder receiver compound
locomotives between the limit of 2 and 2.2, than to go out-
side of these limits with the hope of obtaining greater
economy. Within these limits, it does not matter so very
much what the ratio is ; but, as has been said before, it is
easier to adjust the equalization of power between cylinders,
particularly for high-speed work, when the lower limit is
used, and in addition better results will be obtained in
starting trains.
Exact equalization of power is not necessary, or perhaps
desirable. A variation of 10 per cent, either way will pro-
*duce no harmful results. In the case of some recent two-
cylinder receiver compounds, the greatest variation in
power from starting to a speed of 67 miles per hour is 5
per cent. This is a remarkably close equalization.
51. Ratio of Cylinders and Equalization of Power
in Non-Receiver Compounds. — For four-cylinder receiver
or non-receiver compounds having duplicate sets of cyl-
inders on the two sides, where the equalization of power
is not so desirable as in two-cylinder receiver compound
locomotives, a ratio of from 2.7 to 3.2, as limits, can be
chosen without error and without materially affecting the
economy in locomotive work. Probably a ratio of 3, for
the present at least, will be found perfectly satisfactory.
If the time ever comes when a better positive acting
valve motion is devised, 8, 82, and one that will, with the
assistance of larger valves and steam passages, give quicker
and greater port openings and will postpone the point of
76 COMPOUND LOCOMOTIVES.
compression nearer to the end of the stroke, then these
remarks about the cylinder ratios for compound locomotives
will perhaps need to be modified ; but until then the limits
of ratio given will be found satisfactory.
52. Ratio of Cylinder Volumes to the Work to be
Done. — The ratio of the cylinder volumes, not to each
other but to the work to be done, is an important matter.
In general, in this country, the two-cylinder receiver com-
pounds have had less volume than they should have for the
work they have been designed to do. This has perhaps
been caused by the timidity with which designers have
undertaken larger cylinders with their consequent heavier
reciprocating parts for American engines. The cylinder
volumes used in Europe for the same work are greater in
proportion to the hauling power of the locomotive, as
determined from the total weight on drivers, than they
are here, Table L, Appendix Q. On the other hand, the
four-cylinder non-receiver engines built here have had cyl-
inder volumes more in proportion for the work to be done,'
and more in accordance with European practice. This
appears from Table L, which gives the comparative'cylinder
volumes of several designs. An increase of total cylinder
volume for two-cylinder compounds above that now gener-
ally used in this country is certainly necessary if the best
attainable efficiency is sought.
For the Vauclain compound the Baldwin Locomotive
Works have used the following formula for a number of
engines, but at the present time they are using a formula
having a somewhajt different coefficient, instead of 2.7,
and this gives larger cylinders for the same weight of
locomotive :
2-7PS.
d2 = -i- d'2.
TOTAL EXPANSION RATIO OF CYLINDERS. 77
In these formulas the following are the meanings of the
symbols used :
P = Pressure, by gauge, at admission to h. p. cylinder.
S = Stroke in inches.
D = Diameter of drivers in inches.
W = Weight on drivers in pounds.
d = Diameter of h. p. cylinder in inches.
d'= Diameter of 1. p. cylinder in inches.
Mr. von Borries has recently said that, in his opinion, at
the present time the following proportions should be used :
Cylinders. — Diameter d of 1. p. cylinder to be calculated by the formula
d£-4T.D.
p. s.
if the full tractive force is to be used as in ordinary goods engines. In this formula is :
T = Tractive force ^ -^fa of adhesive weight.
D = Diameter of driving wheels.
p = Boiler pressure.
s = Stroke of pistons.
For passenger and fast-traffic engines, where calculation is difficult, the diameter
of 1. p. cylinder of compound -engines to be i^ the diameter of cylinders of single
expansion engines, raising the steam pressure at least 15 pounds.
Diameter of h. p. cylinder to be 0.7 of 1. p.
Receiver. — The volume must not be smaller than h. p. cylinder, better 1.50 of
this.
Ports. — The dimensions of ports are shown in Table M.
TABLE M.
H. p. cylinder.
L. p. cylinder.
Clearance (including ports), - - -
0.05
0.07 of volume of 1. p. cyl.
Area of ports,
Width of ports,
Length of ports, ------
0.04
0.056
0.56
0.07 of area of 1. p. cyl.
0.07 diameter of 1. p. cyl.
0.77
For freight engines dimensions of ports can be 5 per cent, smaller.
Motion and Slide-Valves.— If t, is the width of 1. p. steam-port the following
proportions should be used :
Travel of valves for middle position of link, -' - - - - 1.6 .t
Outside lap of both valves, - 0.7 1.
COMPOUND LOCOMOTIVES,
Inside clearance of h. p. valve, - 0.20 t.
Inside clearance of 1. p. valve, -------- o.
The corresponding sections of slide-valves and faces are shown in Fig. 27. The
dimensions are given in proportion to t as a unit.
The link-hanging rods to be made of different length, so that 0.4 cut-off in h. p.
cylinder corresponds to 0.5 in 1. p. cylinder.
Greatest cut-off running forward to be 0.77 in h. p. and 0.8 in 1. p. cylinder.
HiqHP.VALYE.
5.7— H H
—3.1 f L3CH
fcS^l b^l
LOWP.VALVH.
6.6
FIG. 27.
von Berries' Proportions of Valve Dimensions.
Mr. A. Mallet and Mr. A. Brunner have found from
experience that a ratio of 2.25 is preferred to any other
for cylinders of two-cylinder receiver compounds.
With
FIG. 28.
Lapage Double Cylinder.
this ratio these designers have used the same cut-off in
both cylinders. With a ratio of 2 a longer cut-off is needed
in the 1. p. cylinder.
It would se'em that the proposition of Mr. Mallet, and
later by Mr. R. H. Lapage, to use a double 1. p. cylinder,
as shown by Figs. 28, 29 and 100, would effectually dispose
of the problem of finding room for a large 1. p. cylinder.
TOTAL EXPANSION RATIO OF CYLINDERS. 79
When this double cylinder is used in conjunction with a
crosshead of the Vauclain type, shown in Fig. 119, it is not
clear why a two-cylinder receiver compound, if such it
could then be called, having in reality three cylinders,
FIG. 29.
Lapage Double Cylinder.
could not be built with sufficient cylinder capacity for any
of the largest locomotives now made. This proposition has
considerable merit, and if two-cylinder compounds with
receivers are continued in use, and there is much prospect
that they will be, it is probable that some extended practical
use will be made of this suggestion.
CHAPTER VIII.
RECEIVER CAPACITY, RE -HEATING AND SEQUENCE OF
CRANKS.
53. Receiver Capacity. — The capacity of a receiver
can be properly based on the capacity of the h. p. cylinder.
In general, the greater the capacity of the receiver the
more readily can the equalization of power between the two
cylinders be accomplished by an adjustment of the cut-off,
22, in the cylinders, and the less will be the effect of a
change in the sequence of the cranks. Large receiver
capacities give less variation of pressure in the receiver, and
in this way are conducive to economy. The ratio of the
receiver volume to the volume of the h. p. cylinder now
commonly used for locomotives is given in Table Ui.
Probably in no case is it advisable to use a receiver with
less capacity than 2.3 times the volume of the h. p. cylinder,
and it is better to use a higher ratio. Some successful
four-cylinder receiver compounds have a receiver volume
4*/z times the volume of the h. p. cylinder. The prevailing
practice here is shown by Table Ui. For comfortable
working the volume of the receiver should not be less than
2.5 times the volume of the h. p. cylinder.
Mr. A. Brunner, who has made many designs of com-
pound locomotives for Mr. Mallet, is of the opinion that
the receiver should have from 4 to 5 times the volume of
the h. p. cylinder.
54. Re-Heating and Steam Jackets. — The receivers
should be located in as hot a place as possible ; not so
much to gain re-evaporation or super-heat as to prevent
condensation. If the receiver is exposed to the atmos-
80
RECEIVER CAPACITY RE-HEATING. 8 I
phere, the condensation in cold weather would be so
enormous as to offset any possible saving from compound-
ing. There is no doubt but that some re-evaporation of
the moisture in the steam does take place in the receiver of
a compound locomotive when the receiver is in the smoke
box, more particularly when the engine has short tubes and
is working hard, as on a grade, or whenever the conditions
are such as to give a high smoke box temperature ; but there
is probably no material saving in present designs of com-
pound locomotives over single expansion engines that results
from re-evaporation in the receiver. The re-heating must
be small owing to the short time, about one-third to one-
fifth of a second, that the steam is in the receiver when the
engine is at speed. However, all that is gained by re-
evaporation is purely a saving, for the smoke box heat
which produces the re-evaporation would otherwise be
wasted through the stack. If a steam jacket is used on the
receiver, or on either of the cylinders, the steam used in it
for re-heating would be used in the cylinders if there were
no jackets, and therefore the saving in the cylinders from a
steam jacket is offset by the loss of the steam used in the
jacket. Mr. F. W. Dean has tried a steam jacket on a two-
cylinder receiver compound locomotive for the Old Colony
Road, but it was finally abandoned on account of the
difficulty of draining it, and the engine now runs without
the steam jacket. The space in the jacket now serves to
give better heat insulation to the h. p. cylinder on which the
jacket is placed.
As it does not matter much in a compound engine
whether the jacket is on the receiver or the h. p. cylinder,
it is probably better, if a steam jacket is wanted, to put the
receiver into the boiler itself, as has been done on a Lindner
compound in Germany. This plan removes any difficulty
of draining the jacket and gives the highest possible value
to steam jacketing. However, as has been said, the re-
82 COMPOUND LOCOMOTIVES.
heating in the receiver brought about by a steam jacket is
not all gain, as, there is some loss of steam in the jacket or
in the boiler as the case may be ; but with re-heating by the
smoke box gases, all re-heating is purely gain. It is prob-
able that such gain as is obtained from re-evaporation in a
receiver in a locomotive smoke box, under ordinary con-
ditions, is greater than could possibly be obtained from a
steam jacket on either the receiver or the h. p. cylinder.
It is now generally understood that a steam jacket on the
1. p. cylinder is not conducive to economy.
In order to gain all that is possible by a re-evaporation
in the receiver produced by the heat in the smoke box gases,
it is better to use a large receiver made of one or more
copper pipes. It seems impractical to put these pipes in
the hottest part of the smoke box ; namely, in front of the
tubes, because of the difficulty in reaching the tubes for
cleaning and repairing ; hence, it is customary to put the
receiver pipe around the top of the smoke box, either for-
ward or back of the smoke-stack opening.
Cast iron receivers have been used generally in this
country. They cost less and have greater durability than
copper. It is not now known whether the thin copper
receiver gives a compound locomotive greater efficiency than
a cast iron receiver.
55. Smoke Box Temperatures. — Smoke box tem-
peratures vary from 400 to 1,200 degrees, according to
the forcing of the engine and the length of the tubes.
Recently there has been a decrease in smoke box tem-
peratures with new designs of locomotives, resulting from
the use of larger fireboxes and longer tubes, and it is
probable that smoke boxes will be run at a lower temperature
in the future than they now are, but in no case will they
reach so low a temperature as to remove all value for the
purpose of re-evaporating moisture in the steam in the
receiver of two-cylinder receiver compound locomotives.
RECEIVER CAPACITY RE-HEATING. 83
56. Sequence of Cranks. — At the commencement of
the use of compound cylinders for locomotives it was
questioned whether the h. p. or the 1. p. crank should pre-
cede in rotation, but as soon as the receiver capacities were
made sufficient, it was found that there was little or no
difference which crank had precedence in receiver engines.
For non-receiver engines it would make quite a difference
which crank precedes if the cranks were placed at an angle
with each other, but as non -receiver compounds for locomo-
tives are only made with the h. p. and 1. p. pistons con-
nected to the same crank, it is not necessary to discuss this
special case. Practically, the sequence of cranks need not
enter as a problem for solution in compound locomotive
designing.
CHAPTER IX.
MAXIMUM STARTING POWER OF LOCOMOTIVES.
57. Starting with Close Coupled Cars and with
Free Slack. — In starting a train it makes considerable
difference whether the train is close coupled, like a vesti-
buled passenger train, or has free slack as with a link and
pin coupling. With a close coupled train it is more difficult,
as the locomotive can only move forward a very short dis-
tance before the entire load has to be started, whereas with
free slack the locomotive can frequently move a full revo-
lution before taking up the last car. For this reason com-
pound locomotives have given more trouble in starting
passenger trains than freight trains.
58. Starting of Two-Cylinder Receiver Compounds
without an Independent Exhaust for High-Pressure
Cylinder. — Two-cylinder compounds can generally acceler-
ate passenger trains without difficulty, but there are certain
positions of the cranks in which such locomotives have a
reduced power, and when in such position the two-cylinder
compound of this type does not accelerate trains, either pas-
senger or freight, as satisfactorily as the ordinary or single
expansion engine. The reason is, that while the maximum
turning moment of a compound locomotive at starting,
which occurs when the 1. p. crank is nearly on the quarter,
is greater than the starting power of a single expansion
engine as a rule, yet the minimum starting power, which
occurs when the h. p. crank is about on a quarter, is consid-
erably less than with the single expansion engine. This
result comes from the comparative size of the h p. cylinder,
it being but little if any larger than one cylinder of a single
84
MAXIMUM STARTING POWER OF LOCOMOTIVES. 85
expansion locomotive, and yet has a back pressure on one
side of the piston very nearly equal to one-half the boiler
pressure, whereas the single expansion cylinder has but a
very small back pressure. Hence, while the compound has,
perhaps, 10 per cent, larger cylinder, it has fully 40 percent,
less effective pressure. This is probably all the argument
that is necessary to show why it is that the practical con-
ditions of operation compel the use of a larger cylinder on
the h. p. side of the two-cylinder compound than is generally
used for a single expansion engine. See Chapter XVII for
argument about recent tendency in starting gears.
59. Starting of Two-Cylinder Receiver Compounds
with Independent Exhaust for High-Pressure Cylinder.
-The engines of this' class start and accelerate trains
equally as well as single expansion locomotives, and are
practically such at low speeds when the separate exhaust is
opened. At higher speeds, the small opening allowed for
the separate exhaust generally causes considerable back
pressure, and the engine will not work well with single
expansion for that reason. This class of compounds can
generally start heavier trains than single expansion loco-
motives of equal rating, for the reason that the cylinders
are larger ; but, of course, the limit of all traction engines
lies in the adhesion of the drivers to the rails ; hence, the
additional cylinder power of this type of compound is of no
advantage after the limit of adhesion is reached.
60. Starting of Four-Cylinder Two-Crank Receiver
and Non-Receiver Compounds. — The four-cylinder two-
crank compounds do not have the disadvantage common
with two-cylinder compounds without separate exhaust for
the h. p. cylinder, at starting, as live steam can be used
in both 1. p. cylinders, one on each side, and the engine
can be started under a heavier load than it can haul
under normal conditions of compound working. Generally
speaking, four-cylinder two-crank compounds have more
86 COMPOUND LOCOMOTIVES.
starting power and more ultimate hauling power than single
expansion locomotives of equal rating. This applies to four-
cylinder tandem receiver compounds and all four-cylinder
compounds having but two cranks. This increase of hauling
power is one of the strong claims made by the advocates of
four-cylinder two-crank compounds. In cases where it is
customary for single expansion engines to separate trains in
two parts and pull each part separately over a heavy grade,
joining the train together again on the other side, generally
called "doubling the hill," the four-cylinder two-crank com-
pound and the two-cylinder receiver compound having inde-
pendent exhaust to the open air for the h. p. cylinder, can be
made to haul the entire train over the hill by using steam
directly from the boiler into the 1. p. cylinders and running
the train at a comparatively low speed. This is certainly a
decided advantage on some roads.
61. Starting of Four-Cylinder Four-Crank Com-
pounds with Receivers. — The starting power of four-
cylinder four-crank compounds depends upon the location
of the cranks, and whether parallel rods are used. With
some of these types the starting power has been small ;
with others it has been ample, 128-134. See Appendix K.
62. Starting and Hauling Power of Single Expan-
sion Locomotives. — The following formula has been much
used for the tractive power of locomotives :
D
in which d— the diameter of the cylinders in inches, p — the
mean effective pressure in pounds per square inch, s = the
stroke in inches, D — the diameter of the driving wheels in
inches, and T— the tractive power or pull at the rail in
pounds. This formula is based upon the fact, that, neglect-
ing friction, the work done in both cylinders during any
period, such as one revolution, is equal to that done at the
circumference of the driving wheel during the same time. It
MAXIMUM STARTING POWER OF LOCOMOTIVES. 87
is convenient and practical, as it gives the hauling power
of the locomotive when the mean effective pressure in the
cylinders is known. The tractive power by this formula
includes the power necessary to move the entire mechanism
of the locomotive and the locomotive itself. It is, in fact,
the entire work done in the cylinders reduced to an equiva-
lent pull on the rail. In using it, a deduction must always
be made for the internal friction of the engine and for
the power required to move the engine and tender in order
that the actual pull on the train itself may be determined.
Some have made the error of assuming a universal value for
/, namely, 85 per cent, of the boiler pressure. This is
greatly in error when applied to some engines, and the only
safe way to use the formula for a given engine is to deter-
mine, by taking indicator cards from the engine in question
or a similar one, what is the real maximum mean effective
pressure. The method of deducing this formula will be
found in Appendix H. It follows from the method of
deduction that this formula gives an average value for the
pulling power, and therefore that, while it furnishes a ready
method of comparing the pulling power of locomotives
under ordinary conditions, it is of very little use in estimat-
ing the first starting power from a stand-still, since the
minimum pull, and not the average, is the practical measure
of the initial starting power of the locomotive.
In the single expansion locomotive, assuming that steam
can be admitted during the full stroke, and neglecting the
effect of angularity of connecting rods, the minimum pull
occurs when one crank is on the half centre, the other being
.at a dead point, and the maximum pull is developed when
both cranks make an angle of 45 degrees with the centre
line through the dead points. This can be readily demon-
strated by calculation, or by a graphical construction.
63. Graphical Representation of Hauling Power.—
There are several methods of representing rotative efforts
COMPOUND LOCOMOTIVES.
graphically, one of which is shown by Fig. 30, in which the
dotted line a . . a represents the rotative effort, or the tan-
gential pull or push, on one crank pin, and b . . b is that of
FIG. 30.
Diagram Showing Combined Starting Power of Both Cylinders of a
Single Expansion Locomotive.
the other at right angles to it, the steam pressure being
assumed as constant throughout the stroke.
The method of construction is as follows : Let A B be
the length of the circumference of a circle, of which CD,
Fig. 31, is the radius. It can be readily shown that the
component D F, of the pressure on the piston D H, which
tends to produce rotation, is proportional to the sine of the
angle a, through which the crank has-
turned from a dead point. Divide the
line A B and the circumference in Fig»
31 into the same number of equal parts.
Then through the points of division on
A B lay off perpendicular distances,
such as k d, equal to the lines which
represent the sines of the angles in
Fig. 31, such as K D.
The dotted curve a a represents the variations in rotative
efforts on the crank starting from C L during one revolution,
and the curve b b, shown by a broken line, represents the
variations in efforts on the crank starting at C M, or at
right angles with the first.
The total rotative effort is shown by the ordinates of
the full line curve in Fig. 3'o, which is obtained by adding
FIG. 31.
MAXIMUM STARTING POWER OF LOCOMOTIVES. 8<>
the ordinates of the curves for the single crank, for example,
fm—fg-^fk. It is evident that the value of the total
efforts varies between A N and k e. In the first case, one
crank is on the dead point, and the other is on the half centre,
or midway between the two dead points. The pull at the
rail is then :
\K d2 x / X s -5- A
Which is .7854 of the tractive power as found by the
ordinary formula. In the second case the pull is twice
that of one crank when making an angle of 45 degrees
with the centre line, or it is
|-d2x/>x2x .707^ , -^- A
Which is i.i i of the tractive power as usually estimated.
It is also clear that there are four maximum and four
minimum points during a revolution. These values are
determined as has been said, on the basis that a constant
steam pressure can be maintained throughout the stroke,
which would be the case in starting if steam could be
admitted to the cylinder during the whole stroke. But when
the latest cut-off takes place, when the piston is some dis-
tance from the end of the stroke, as, for example, at 21
inches with 24 inches stroke, the engine will have a weaker
position for starting than that given above as a minimum.
When one piston is 21 inches from the beginning of its
stroke the other will be about 4 inches from the begin-
ning of its stroke, and its crank will have turned through
about 50 degrees from a dead point. If cut-off takes place
at 21 inches, no steam can be admitted to that cylinder
during the remainder of the stroke, that is, if the start occurs
with the piston in this position, and the work of starting
devolves upon the other cylinder.
When the piston has moved 4 inches from the begin-
ning of the stroke the rotative effort is about ^ of the
maximum for one cylinder, and is, therefore, about .589
of the tractive power as usually estimated. This cor-
QO COMPOUND LOCOMOTIVES.
responds to an ordinate of the curve a a, •& little to the
right of k d, and is evidently the most difficult position
from which to start the single expansion locomotive. The
reduction in the rotative effort on account of the fall in
pressure due to the expansion after cut-off and release will be
slight. This can be shown on the diagram by laying off
radial distances such as C P and C R on the proper
radii to represent the pressures for these crank positions,
and using the lines P Q and R S for ordinates in Fig. 30,
instead of those used before. The final effect is shown by
the dotted curve at ??, Fig. 30.
As the locomotive starts the mean effective pressure in
the cylinders will be somewhat reduced, but the reduction
will not be of large amount within what may be called the
starting limits, or until the link would ordinarily be hooked
up. As the speed increases the inertia of the reciprocating
parts, etc., will be sufficient to modify the form of the
diagram of crank efforts, but it is not necessary to consider
that in estimating the initial starting power.
64. Starting Power with Mallet's System and other
Non- Automatic Starting Gears. — Turning now to the
compound locomotive, it is apparent that in the Mallet and
other systems having independent exhaust for the h. p.
cylinder the starting conditions are almost identical with
those in the single expansion locomotive. If the h. p.
cylinder is of the same size as one cylinder of the single
expansion locomotive, and the cylinder ratio is 2, it is
only necessary to admit steam of one -half the boiler
pressure to the 1. p. cylinder in order to have starting power
equivalent to that of the single expansion engine, the same
boiler pressure being used. If the 1. p. initial pressure is
greater than one-half the boiler pressure, the starting power
of the compound will be greater than that of the single
expansion engine in all positions in which the 1. p. cylinder
is available for use in starting, that is, except when the 1. p.
MAXIMUM STARTING POWER OF LOCOMOTIVES. QI
crank is on a dead point, or when the 1. p. valve is in such
a position that steam cannot be admitted. If the boiler
pressure of the compound is higher than that of the single
expansion engine, and the h. p. cylinder is the same size as
one of those of the single expansion engine, the starting
power of the compound engine of this type will be the
greater in about the proportion of the two boiler pressures.
65. Starting -Power with Worsdell, von Borries and
other Automatic Starting Gears. — In the Worsdell and
von Borries type, and others with automatic intercepting
valves, the conditions in starting are quite different from
those just described. When steam is admitted to the
FIG. 32.
Steam Pressure During First Revolution with an Automatic Starting Gear.
receiver by means of the starting valve, the intercepting
valve is closed, and the h. p. piston therefore starts against
the pressure of the steam or air which filled the receiver
just before the starting valve was opened. The amount of
this receiver pressure will depend upon the length of time
during which the engine has been standing, the condition of
. the valves, etc. If at starting the h. p. crank is at a dead
point, the pencil of an indicator, which is applied to the
steam end of the h. p. cylinder during the first stroke, will
trace a line similar to a b c, Fig. 32. The back pressure
acting against the other side of the piston during this stroke
is shown by a line such as d e, the pressure at e being some-
what greater than that at d on account of the compression
Q2 COMPOUND LOCOMOTIVES.
in the h. p. cylinder and receiver. The initial back pressure
is assumed in the present case as equal to the atmospheric
pressure. The diagram, a b c e d, thus represents what may
be called the effective indicator card for the first stroke of
the h. p. piston.
When the h. p. exhaust opens the pressure in that cyl-
inder and the receiver will fall to some point g, which can
be only approximately determined by calculation. It is
located on Fig. 32, by calculation on the basis of no con-
densation or evaporation during the exhaust. The forward
pressure on the h. p. piston during the second stroke will
be similar to that during the first stroke, and is shown in
Fig. 32 by h k I. The back pressure line during this stroke
will consist of, first, a curve g m, which represents the com-
pression by the h. p. piston of the steam which fills the
space between the h. p. piston and the intercepting valve,
until that valve opens ; and second, of a line m n, of nearly
constant pressure, which represents the back pressure
during the remainder of the stroke, after the intercepting
valve opens and the starting valve is closed.
It is generally assumed that the pressure of the steam,
which is admitted directly to the receiver in starting, is
reduced by wire-drawing to about one-half the boiler pres-
sure. Assuming this to be so, the h. p. cylinder back
pressure will become sufficient to open the intercepting
valve when about 5/g of the second stroke has been accom-
plished, as indicated at m, Fig. 32. The net diagram from
which the effective pressure on the h. p. piston for the
second stroke can be obtained is then h k I n m g.
A diagram of rotative efforts constructed from these
indicator cards is shown in Fig. 33 by the curve A E C F B,
from which the reduced effort resulting from the increasing
back pressure during the second stroke is apparent.
The distribution of work in the 1. p. cylinder in starting
does not differ from that in the single expansion engine.
MAXIMUM STARTING POWER OF LOCOMOTIVES. 93
The rotative effort will, therefore, be represented by a curve
such as H K L D M, Fig. 33, which has the same form as the
single crank curves in Fig. 30. The curve in Fig. 33 is
constructed on the basis of the initial 1. p. pressure, being
one-half of the boiler pressure. If the initial pressure is
greater than this, the ordinates of the curve between
H and K, K and D, etc., should be proportionately in-
creased. The combined effort of the two cylinders is
shown in Fig 33 by the full line curve. The intercepting
P Q C
J)
FIG. 33.
Starting Power During First Revolution of a Compound, with
Automatic Starting Gear.
valve opens at about the point f, and from that point the
engine will work as a compound.
It has been already shown that when so working with
the customary pressures the power developed at late cut-
offs is less than that of the single expansion engine. The
location of the point at which the intercepting valve opens
depends upon the pressure in the receiver before starting, the
pressure of the steam admitted to the receiver by means of
the starting valve, and the size and location of the receiver.
For any given combination of conditions it will be found
.at a definite distance from the point C, or from the end of
the first stroke of the h. p. piston. In the present case this
point was found to be about $/% of the stroke from C.
It is obvious that this action is not at all dependent upon
t e first stroke of the h. p. piston, but only upon the exhaust
from that cylinder. It follows from these considerations
that, if the h. p. crank is at a dead point at starting, the
^engine will move through something over ^ of a
94 COMPOUND LOCOMOTIVES.
revolution before compound working begins : but, on the
other hand, if the h. p. piston is at the position correspond-
ing to P, or near the point at which cut-off takes place, the
compound working will begin after about T76 of a revolu-
tion. If the h. p. crank is in some position such as Q, at
which the steam valve is closed, the starting must be
accomplished by the 1. p. cylinder alone ; but after a
slight movement, sufficient to carry the h. p. crank over the
dead point, the cycle will continue as if started at A, the
effect being to prolong the time of direct working of the
1. p. cylinder to about ^ of a revolution.
After compound working commences, and while admit-
ting steam for as much of the stroke as possible, the combined
diagram of rotative efforts would be similar to Fig. 30, but
with a smaller mean effective pressure, the proportion being,
with boiler pressures of 170 and I 50 pounds in the two types,
not greater than 1 10 to 122, as has been already mentioned.
The two diagrams, Figs. 30 and 33, are not drawn to the
same scale of pressures, but the shape of the full line curves
represents with reasonable accuracy the variations in starting
power in the single expansion and compound locomotives.
In conclusion, it appears that, with the pressure customary
in the two forms, the pulling power of the Worsdell and von
Borries type, and others with automatic intercepting valves,
in starting may be greater than that of the single expan-
sion engine having cylinders of the same size as the h. p.
cylinder, during the first half revolution approximately,
but that after this the power of the compound engine
diminishes until it is from So to 85 per cent, of that of the
single expansion engine.
66. Starting Power with the Lindner System.— The
maximum starting power of the two-cylinder Lindner type
with latest type of Lindner starting gear, and without inter-
cepting valve, is about the same as the maximum with the
two-cylinder type having automatic intercepting valves, but
MAXIMUM STARTING POWER OF LOCOMOTIVES. 95
is much less than the two-cylinder type having independent
exhaust for the h. p. cylinder. Appendix L gives analysis
of the starting power of a Lindner engine.
67. Starting Power of Three-Cylinder Three-Crank
Compounds. — The starting power of three-cylinder com-
pounds, when the drivers are coupled together with parallel
rods, is about the same as with the two-cylinder type. If
the drivers are not coupled, as with the Webb type, the ulti-
mate starting power is dependent upon the accidental loca-
tion of the crank at the time of starting. The minimum
starting power for full cut-off and full throttle of a three-
cylinder type without parallel rods is lower than the mini-
mum of the two-cylinder receiver type. See Appendix I.
68. Variation of Hauling Power with Four-Cylinder
Two-Crank Receiver and Non-Receiver Compounds. —
The curve of variation of hauling power during a complete
revolution in a two-crank four-cylinder non-receiver com-
pound or four-cylinder tandem receiver compound, does
not differ materially from that of a single expansion engine,
as both sides are identical in action. However, with the same
number of expansions in the four-cylinder and the single-
expansion engine, the hauling power is more uniform in the
compound, more particularly for the reason that the cut-off
in both cylinders in the compound is later than in the single
expansion engine. In any engine, the later the cut-off the
more uniform will be the hauling power during a complete
revolution at slow speed. At high speeds this is much
modified by the inertia of the reciprocating parts, see
Appendix P. Uniformity of pull on a train is of more im-
portance in starting and at slow speed than at high speed,
as at slow speed a variation-in the pulling power may be felt
by the passengers in a train.
The foregoing statements about four-cylinder compounds
apply more particularly to the non-receiver Vauclain, John-
stone, and tandem types, and to the tandem form generally,
<)6 COMPOUND LOCOMOTIVES.
but are also true of four-cylinder receiver compounds with
four cranks in which the cranks are almost evenly divided
in position on a circle and with parallel rods between the
axles having cranks.
CHAPTER X.
CONDENSATION IN CYLINDERS.
69. Range of Temperature. — When compound engines
are well designed and are working under favorable con-
ditions, the loss from condensation of steam in trie cylinders
should be less than with single expansion. This arises from
the lower range of temperature in the cylinders ; the range
of pressure being less in the cylinders of the compound, it
follows that the range of temperature would also be less.
However, the gain in efficiency by saving in condensation
may be more than offset by results of faulty mechanical
arrangement. If the cylinders, steam passages, and receiver,
are not well protected from radiation, the loss by condensa-
tion from this cause may more than offset the saving from
the reduction of condensation brought about by a lower
range of temperature in the compound cylinders.
70. Need of Covering Hot Surfaces to Prevent Ra-
diation.— It is a very bad, but common practice, in locomo-
tive construction, and one that has descended from the
past, to construct cylinders for locomotives with the walls
of the steam passages exposed directly to the atmosphere
without covering on the outside. Steam chests and cylinder
heads are likewise very poorly insulated in common practice.
The loss from these defects alone is so great that it is
hardly worth while to go to the trouble to use compound
cylinders unless the heat insulation is improved. This
common defect in locomotive construction has been the
subject of severe criticism by mechanical engineers who are
familiar with the better class of designing for marine and
stationary engines. Just now some railroad companies have
97
g8 COMPOUND LOCOMOTIVES.
taken the matter in hand and are using somewhat better
heat insulation for all parts that are exposed. Locomotive
builders, however, have not yet considered it worth while
to reduce radiation by better insulation, probably because
of the lack of appreciation of these losses on the part of
those who purchase locomotives. Mr. F. W. Dean, 54, in
designing some engines for the Old Colony Railroad, has
separated the steam pipes from the walls of the cylinders,
and has used a better degree of heat insulation than is
common. From the results obtained from his engine, it
would appear that the better insulation has been of a
decided advantage. The condensation of steam in a loco-
motive is one of the sources of loss, and the highest
possible saving of the compound cannot be obtained with-
out a proper insulation of all pipes, passages, and recepta-
cles for steam.
71. Condensation, Leakage of Valves and Re-Evap-
oration as Determined from Indicator Cards. — In the
discussion of a method of analysis of combined indicator
cards, the losses due to condensation are considered, 42, 44.
In addition to that discussion, the following further analysis
of Fig. 26, and some cards from other types of engines, will
be found instructive. This analysis shows how the steam
weights calculated from actual indicator cards vary at dif-
ferent points during a stroke in the h. p. and 1. p. cylinders
of two-cylinder receiver and four-cylinder non-receiver
compounds. These results are given in Tables N, J and
O. Table N gives the fundamental data regarding the
engines that is used to make the calculations from the
indicator cards. Table J gives the final results of the
calculation, and shows the weight of steam used per stroke
in both cylinders, and the per cent, of increase or de-
crease of weight of steam used in the 1. p. cylinder above
or below that used in the h. p. cylinder, this data being
taken from the measurements on the indicator cards. The
CONDENSATION IN CYLINDERS.
99
I
S5 ^
S s
§ -I
H cT
J.
•o8 -O
-patpvoi
-IB3 'J3
-paij
•BZ 2g Z SpJB3
-aqAv zi 'ApE}D3U3
3tpg
Tg L SpJE3 M3
zi 'AEpauai
•Eg ^ 9
auM zi '
•s* -ON
•s -ON
•ON P«D -*SE -ON
'lnS°JM ft ^ '9 ''
^-^-H O O •^•
N.;10 "^^
S^-^-M o 0 •
N M • i^ tn^
SO^^M O O ^
5 w j ft invo
f moo m
t^in-
O • Is* 0 r^l t^ u"J ^J- ^-^O
t~- 1 ^-q"Scoc?tCMM
^vo •
H\O •
l-vo • t^O^O^O^^OM-^-
\O • t^wowvoooN-^-
• • . «r^-"j-OfOiriMNH
^- •* 0 N t^oo «-« H t^
§,5: 5- 5-S S S S.'S, S
OO . ^inov >o^O >o w o v
HH' H
^ cToo ^- I^^M O H vo1
M •«• o m TJ-VO JJ H rn
ei ' * ' • ei " ' '
•oNp«D ^£.o3 I 8""^|H?^'
'inS°i\[ •£) ^ 'a "D i „_"_**_
•££
•ON PJBD •& ^ *a
'•3 uo zs -ON umppjg
•iS -oN
A -zS
- OI "
•E8
pat[AV si
•duio3 uiBpnE^ 33
•0|sj '
«°° ET4
x , S.1 11 Ili 1 1 1 1 g*8 B<«-§ =-£^"
ill
100
COMPOUND LOCOMOTIVES.
3uojsuqo|
0 UEDIX3J\[
^00 M ^ J£00_;g NO_ g;
ON W r*1OO •**• ON O rO
auojsuqo
+\<N mw -^-10^0 O r^.G^ • Nvo
xMX Miofimrororo' • .••
» •*..! Irt W O V M M *0 00 .00;*
C4Nrr>rOM-- ". «
H
t^oo -^- ^*- O^OO
oocr, o> ^-o ^-
00 S m ON ON
M^OO^O t^^O
•z -oN pJE3
auojsuqof
'•duio3 auojsuqo
» «
i-ivO
O NO M
-vo ro M
ONf)WO>O
H\00 1000 v
OOClCJOO
'^' b-*OO M
•L9 -oN i
-3J3 uA[>[oojg uo
'•duio3 puEjs
-3|3
\N
HT\
H 00 vo
•S "0N PJE3 'Otz
•ON 'Suft -duio3 ipp
i^sre^gii^oS^
N M t^ ro t^.
vO W
•oft '3ug -duio3 jjap
o •*• "INC o ^*
•£ -o^ pJE3 'o£z
•ON -Sug -dmo3 ipp
JE3.IQ
• , -
t- H 0 ft « *
>Oi^ "^NC> O
"*• "*• ^"S/^ -='C-=^^«-M-M-X; 0"g_= g :A S Ifl on.t;
. o
'
2 2 s
CONDENSATION IN CYLINDERS IOI
weight of steam shown to be in the cylinder at the ter-
mination of the compression, period is subtracted from the
weight of steam in the cylinders near the end of the
expansion period. The remainder is taken as representing
the amount of steam used in the cylinders, as shown by the
indicator cards, 30-31, 42.
Table O shows the distribution of the steam at different
parts of the stroke for an indicator card from the Vauclain
engine. See Fig. 26.
TABLE O.
Giving Calculated Weight of Steam at Different Points of an Indicator Card
from Vauclain Compound No. 82 in C. B. &> Q. Tests.
Weight of steam at point 3, the terminal of expansion in
h. p. cylinder. 5913 Ibs »
Weight of steam in valve at H, the cut-off in 1. p. cylinder .0434 "
Weight of steam in 1. p. clearance space at L 0832 "
Ratio of weight of steam in valve at H to the weight of
steam discharged by the h. p. cylinder at point 3 .... 7.3$
Ratio of weight of steam in 1. p. clearance space at L to
the weight of steam discharged by the h. p. cylinder
at point 3 14.1$ •
Total addition to weight of steam discharged from h. p.
cylinder at point 3 resulting from the admixture with
the steam in valve and that in 1. p. clearance space.
Based on the measurement of the weight in valve at
H and in the 1. p. clearance at L, no allowance being
made for condensation 21.4$
Actual addition to weight of steam discharged from h. p.
cylinder at point 3, based on measurement of indica-
tor card at K 12.0$
Difference between the actual addition of steam weight
measured at K and the addition that would be found
if the steam at H in valve, and the steam at L in 1.
p. clearance space, had been retained without con-
densation or leakage and had been added to that
incoming from the h. p. cylinder, 21.4—12= 9.4$
It has been claimed that the steam pressure in the valve when the h. p.
cylinder exhausts at point 3 is the same as the pressure of that exhaust, but
in this case the valve pressure can be but 49 pounds absolute, or the same as
that at H, while the pressure of the exhaust from the h. p. cylinder is that at
point 3 or 126 pounds absolute.
The weight of the steam in the valve with 49 pounds pressure, absolute, is but
.0434 pounds, while the weight with 126 pounds pressure would be .1205 pounds.
IO2 COMPOUND LOCOMOTIVES.
72. Examples of Determination of Condensation,
Leakage, and Re-Evaporation, from Various Indicator
Cards. — Table J gives some data about steam use in com-
pound locomotives. The columns of particular interest are
those which show the per cent, of increase or decrease
of the steam used in the 1. p. cylinder. It will be noticed
that the cards taken from the two-cylinder compounds show
less steam in the 1. p. cylinder than in the h. p. This would
point to a condensation somewhere, but it is not possible to
say where it takes place without further analysis. It may
be in the receiver, as in any compound engine with a
receiver, if the receiver is not provided with an efficient
re-heater, there is some loss of steam weight. This is very
well shown in some tests of a triple expansion engine made
by Professor Peabody, of the Massachusetts Institute. From
the results of the analysis of the cards from the C., B. & Q.
compound it will be noticed that the crack in the cylinder
saddle caused so much leakage as to show a considerable
increase of steam used in the 1. p. cylinder. In closing
upon this very important matter of the relative amounts of
steam shown in the h. p. and 1. p. cylinders, it is necessary
to add that a 10 per cent, difference in the steam used by
the two cylinders is not necessarily followed by a 10 per
cent, loss of efficiency in the engine, and it may be that no
material loss follows as much difference as this, for much
depends upon the grade of expansion and conditions, 42, 44.
The object of making such analyses as this is, to learn
about the rate of re-evaporation in compound locomotive
cylinders. Re-evaporation must not be confused with leak-
age. With steam containing moisture when the volume
increases the apparent weight of steam increases also. This
arises from the fact that as the steam expands there is more
heat in it than is necessary to keep the steam at the
temperature corresponding to the reduced pressure, and
also some heat is given back from the cylinder walls, which
CONDENSATION IN CYLINDERS. IO3
have been previously heated, and this extra heat goes to
evaporate some of the moisture that is contained in the
steam. This moisture results from the condensation while
the steam is entering the cylinder from the boiler up to
cut-off. The amount of steam condensed varies materially
with different engines, but a rough approximation shows
that the Baldwin engine on this test condensed something
over 30 per cent, of the entering steam while the cylinders
were being filled from B to E, Fig. 26. The condensation
in some types of engine runs as high as 60 per cent., and in
other engines, under particularly favorable conditions, as low
as 20 per cent., and perhaps even lower in the first cylinder
of the best designed triple expansion engines with steam
jackets. Just as the steam condensed during admission
evaporates during expansion, on account of the excess of
heat over and above that necessary to keep the steam at a
temperature corresponding to the pressure, and further by
the heat received from the cylinder walls, so during com-
pression some of the steam condenses by reason of the heat
taken from it to heat up the cylinder head, the piston head,
and the walls of the steam passage. These analyses of loss
of heat, and the corresponding loss in steam weight, are
interesting mainly in showing that the actual steam lines
do not correspond with the usual theoretical steam line
drawn for the sake of comparison on combined indicator
cards, 43.
The hyperbola which is frequently drawn to show
whether the engine leaks or not, does not take into account
the full change in temperature during expansion, 41, 43. The
adiabatic curve is an approximate curve which approaches
very closely to the theoretical expansion of steam while
doing work when there is no loss or gain of heat due to
the heating of cylinder walls, etc. It takes account of the
heat taken from the steam to do work. Owing to the re-
evaporation in steam cylinders, it is generally the case that
V*" 0» TH**NP
wiraasjTr]
104 COMPOUND LOCOMOTIVES.
the hyperbola corresponds more nearly to the actual
expansion line on an indicator card than does the adiabatic.
In compression the actual compression line differs widely
from both the hyperbola and the adiabatic, 6.
The weights of the steam present in the cylinders have
been calculated for several points during the expansion of
the steam in the two cylinders, Fig. 26, and are as follows :
The weight at point I is .57 pounds; at the point 2 it
is .58 pounds; at the point 3 it is .59 pounds. Thus is
shown the continual re-evaporation and corresponding
increase in apparent steam weight during expansion in the
h. p. cylinder.
The subject of cylinder condensation is a very complex
one and cannot be treated here from a theoretical stand-
point, as theoretical studies of the subject are of little value
unless the constants of heat absorption are known. These
have never been determined for locomotives. The most
practical instruction is : insulate all exposed hot surfaces of
the boiler and live steam passages and receptacles as fully
as the best insulation will allow, and do this regardless of
cost where fuel is high in price, 70.
CHAPTER XI.
THE VALVE GEAR ADJUSTMENTS.
It has been shown that when the valve motion is good
and the receiver is of large volume, the division of the
total work between h. p. and 1. p. cylinders can be equalized
with sufficient approximation for practical work by ad-
justing the cut-off in the cylinders. This is readily ac-
complished for locomotives that run always in the same
direction by adjusting some part of the valve gear without
increasing the complication. This is true of the Stephen-
son, Allen, Joy, Walscheart, and other positive motions.
It is generally accomplished by changing the position of
one of the links with respect to the other, either by short-
ening or lengthening the link hanger, or by off-setting one
of the arms of the reverse shaft. Several modifications of
the link motion that have been adopted to change the
relative cut-off in the cylinders will be given in what
follows.
For locomotives that run in both directions the adjust-
ment of the cut-off is more difficult, and the devices for
doing this introduce some new details of construction and
are in some cases complicated. The simplest way in which
to get a difference in cut-off in the cylinders, in both for-
ward and back motion, for locomotives that run in both
directions, is to give a different valve travel or outside lap'
to the different cylinders. In all cases not enough differ-
ence can be produced in this way to accomplish the desired
result without making the steam distribution in one
cylinder much less efficient than in the other, but where
the cylinder ratio is selected within the proper limits, and
105
106 COMPOUND LOCOMOTIVES.
the receiver has sufficient capacity, and the valve travel
and steam ports are ample, the adjustment can be made
with perfect satisfaction by changing the travel or outside
lap to adjust the cut-off, 45-56, 77-81. In Tables P, Q, R,
S, T, U, Ui and V, will be found the result of some changes
of this kind and the opinions of various designers on this
matter. With the Joy gear, the variation in cut-off may be
produced by inclining the sliding links to each other.
73. Mallet's System of Cut-Off Adjustment. — In the
earlier Mallet engines the lifting shaft is divided so that
th$ valve motion of each cylinder is to a certain extent
FIG. 34.
Mallet Regulating Device.
independent of the other. The h. p. valve gear is con-
trolled by a screw and nut, which takes the place of the
ordinary quadrant. The nut which is on the h. p. reverse
lever carries a short sector or quadrant, and a latch on the
1. p. reverse lever works in this sector. ' The effect is that
both cylinders can be reversed by moving the h. p. lever ;
while by adjusting the 1. p. lever the cut-off in that cylinder
may be made either later or earlier than in the h. p. cylinder.
Mr. Mallet has adopted a differential motion for the
purpose of obtaining a later cut-off in the 1. p. cylinder in
both forward and backward gear. The principle of this
motion is illustrated by Fig. 34. In this Fig., A is the
VALVE GEAR ADJUSTMENTS,
107
lifting shaft and B is an auxiliary shaft. The lifting arm
M of the h. p. link and the arm C are keyed to the lifting
shaft, while the 1. p. lifting arm N and the arm H are in
one piece, which turns about this shaft. The slotted arm
D and the arm E are keyed to the auxiliary shaft. The
arm C carries a block which slides in the slotted piece D.
The parts are shown in Fig. 34 in a position for backing,
the 1. p. link being raised higher than the h. p. link and
therefore cutting off later. In full backing gear the arms
M and N would be parallel and hence give the same cut-
off in both cylinders. In mid-gear the arms C and D are
on the center line A B, while in forward gear or to the left,
the lifting arm N is lowered more rapidly than the arm M.
Mr. Mallet gives the following as the distribution obtained
with this arrangement :
Forward Gear.
High-pressure cylinder 70 .60
Low-pressure cylinder 70 .65
•50
.60
.40
•55
•30
•50
j Backward Gear.
.0 .0 .60 .70
.0 | .0 .65 .70
FIG. 35.
C. B. & Q. Link Hunger Adjustment.
io8
COMPOUND LOCOMOTIVES,
FIG. 36.
Chicago, Burlington & Quincy Gear.
74. Chicago, Burlington & Quincy System. — Mr.
William Forsyth, Mechanical Engineer of the Chicago, Bur-
lington & Quincy Railroad, has designed a variable cut-off
gear for the two cylinders of a Lindner compound by making
one of the reverse shaft arms loose on the shaft. The loose
arm is a bell crank with a vertical arm similar to the one used
for reverse shafts on American engines. From the top of
the loose arm a short reach rod runs back about four feet,
and is there attached to the main reach rod running to the
reverse lever. With this arrangement, by making one of the
vertical arms shorter than the other, a movement of the
reverse lever causes a different angle of rotation of the two
VALVE GEAR ADJUSTMENTS,
IOQ
reverse shaft arms, and one link can be dropped lower than
the other while running in either direction. This arrange-
ment worked satisfactorily and the distribution was excel-
lent. It was found, however, that the lengthening of the
1. p. link hanger accomplished the same end, for regular
freight engines, and the second compound was built with the
hangers at different length, as given in Figs. 35 and 36.
75. Heintzelrhan System. — On the Southern Pacific
the following plan for adjusting the cut-off has been devised
by Mr. T. W. Heintzelman. See Figs. 37 and 38.
FIG. 37-
Heintzelman Gear.
The horizontal arm of the reverse shaft has a slot in
which slides a block. To this block is attached the upper
end of the link hanger, and also one end of a horizontal
link. The horizontal link at the other end is attached to a
bracket on the guide yoke or any other convenient part of
the locomotive. This device is put on the h. p. side of the
engine. Referring to Figs. 37 and 38 it will be seen that
the link block is shown in the centre of the link. It is evi-
no
COMPOUND LOCOMOTIVES.
dent that if the reverse shaft be dropped from the position
shown, the block in the slot in the reverse shaft arm, as
well as the upper end of the link hanger, will be pulled, by
means of the horizontal link attached to the bracket, to a
FIG. 38.
Heintzelman Gear.
position further to the left, or toward the end of the reverse
shaft arm, than is shown. Meantime, the upper end of the
link hanger on the other side of the engine has remained at
the same distance from the centre of the reverse shaft. The
effect of dropping the horizontal reverse shaft arm to the
lowest position to put the engine in full forward gear, is to
bring the upper ends of both link hangers in the same rela-
tive position with respect to the reverse shaft, and give the
same cut-off in both cylinders in full forward gear. At all
other positions of the link, the block in the reverse shaft on
the h. p. side is nearer the centre of the reverse shaft, and
the effect is the same as if a shorter reverse shaft arm, and
one of variable length, was used on the h. p. side. In this
way the 1. p. link is lower than the h. p. link, for all cut-offs
except that of full forward gear, hence the cut-off is longer
VALVE GEAR ADJUSTMENTS.
Ill
in the 1. p. cylinder than in the h. p. The effect of this
device on the distribution of steam power in the cylinders
and on the relative cut-offs is given in Table P.
TABLE P.
Heintzelman djustment of Cut-off and Per Cent, of Power in H. P.
and L. P. Cylinders. See Appendix R.
Cut-off h. p.
cylinder, inches.
Cut-off 1. p.
cylinder, inches.
Per cent, of total work
done in h. p. cylinder.
Per cent, of total work
done in 1. p. cylinder.
233A
•2.^/2
205/8
15
I2&
9H
23^
227/8
2l7/8
I8#
17
15
4I-I5
43-18
41.64
46.28
45-04
49.08
58.85
56.82
58.36
53-72
54.96
50.92
76. The Rogers Locomotive Works Link Hanger
Adjustment. — The Rogers Locomotive Works have used a
link hanger in two parts, each part being provided with
teeth to prevent slipping. In this way the bolts can be
loosened and the link hanger be made longer or shorter as
desired.
76a. Different Adjustments of Cut-Offs That Have
Been Used for Compound Locomotives. — Mr. von Borries
from his experience has finally settled on the following ratio
of cut-offs in the h. p. and 1. p. cylinders as being in his
opinion best adapted for average work. See Fig. 27.
Cut-off H. P. Cylinder, per cent. 30 40 50 60 70 78
L. P. " " 40 50 58 65 73 80
After a number of experiments Mr. Joseph Lythgoe, of
the Rhode Island Locomotive Works has decided to use
\Ytf in. outside lap on the h. p. cylinder, and % in. lap on
1. p. cylinder. This gives about 3^ in. later cut-off in the
1. p. cylinder for a 24 in. stroke, and it is believed will so
satisfactorily adjust the cut-offs that a change in the length
of the link hanger will not be needed. This plan has the
advantage of giving the same relative cut-offs in both cylin-
ders whether the engine is going ahead or backing. The
valve travel used with this amount of outside lap is 6j^ ins.
112
COMPOUND LOCOMOTIVES.
TABLE Q.
Giving details of Valve Movement and Port Openings on Dean Compound.
Locomotive on Old Colony R. R. Cylinders 20 in. and 28 in. X 24 in. Drivers
6g in. Diameter. Valve Travel 6% in. Outside Lap i in. Inside Clearance
or Negative Lap % in. See Appendix R.
h. p
Cut-off Cut
20%
18
16
13%
9i96
20%
17%
12
9i-i
l. P.
off
21
1 9 iV
14%
12%
17%
15%
"X
10%
h.p.
Lead.
A
A
I.P.
Lead.
61!
/o
h. p.
Release.
22^8
21%
20%
19
17%
i5X
22%
21
20 A
Release.
22%
20%
17 A
22%
21 H
20|f
I9X
18%
h. P.
Compres-
sion.
23A
22;
22
2IJ
20;
23%
22H
22 ^
20X
l.p.
Compres-
23A
23
22%
22%
21 H
21%
20%
23%
22}|
22%
22%
20%
Port
Opening,
h. p.
Port
Opening.
1. p.
2%
I
y
H
TABLE R.
Giving Details of Valve Movement and Port Openings on Dean Compound
Locomotive on Lehigh Valley R. R. Cylinders 20 in. and 30 in. X 24 in. Drivers
jo in. Diameter. Valve Travel h. p. 5 in., I. p. 6% in. Outside Lap h. p. %.
in., 1. p. /% in. Inside Clearance or Negative Lap h. p. T3g in., I. p. o in. See
Appendix R.
w
h. p.
Cut-off Cut'-off
20
18
16
17
19%
19%
18%
17%
16%
h. p.
Lead.
V
X
A
X
H
U
iii
i. p.
Lead.
Line
I
Line
h. p.
Release.
22%
21%
20%
19%
18%
I7K
22%
21%
21%
20^
19 II
Release.
22%
20%
19
22{|
22%
2IJ1
21%
20%
h.p.
Compres-
sion.
23
22%
21 H
20%
20
19
22 it
22X
l.p.
Compres-
22 A
2I-lV
20%
19%
16%
22^
21%
21%
20^
20
h.p.
Port
Opening.
I}7!
iS
l.p.
Port
Opening.
H
A
VALVE GEAR ADJUSTMENTS,
I I
TABLE S.
Giving the Steam Port Openings of Schenectady (Pitkin) Compound Locomo-
tive on Chicago dr> North-Western R. R. Cylinders 20 in. and 30 in. X 24 in.
Drivers 68 in. Diameter. Valve Travel 6% in. Outside Lap 1% in. Inside
Clearance or Negative Lap, h. p. % in., 1. p. ^ in.
h. p. cyl.
Cut-off Inches.
Cut-off Inches.
h. p. cyl.
Lead, Inches.
1. p. cyl.
Lead, Inches.
h. p cyl.
Valve Opening,
Inches.
1. p. cyl.
Valve Opening,
Inches.
Front
Stroke. Stroke.
I9if
*4iV
Back
Front
Stroke- Stroke.
i9rY
Back
Front
Stroke. Stroke.
20f|
20#'
I6H
14"
12
iftr"
Back
Front
Stroke. Stroke.
Back
Front
Stroke. Stroke.
H"
Back
H"
Front
Stroke. Stroke.
it"
H*
H"
Back
W
H1
TABLE T.
Giving the Steam Port Openings of the Schenectady Compound Locomotive
on Adirondack &° St. Lawrence R. R. Cylinders iq in. and 28 in. X 24 in.
Drivers, 6q in. diameter. Valve Travel, 6% in. Outside Lap, il/fa in. Inside
Clearance or Negative Lap h. p., ^ in. ; 1. p., fa in. See Appendix R.
h. p. cyl.
Cut-off,
Inches.
1. p. cyl.
Cut-off,
Inches.
h. p. cyl.
Lead, I
nches.
1. p. cyl.
Lead, Inches.
h. p. cyl.
Valve Opening,
Inches.
1. p. cyl.
Valve Opening,
Inches.
Front
Stroke
Back
Stroke
Front
Stroke
Back
Stroke
Front
Stroke
Back
Stroke
Front
Stroke
Back
Stroke
Front
Stroke.
Back
Stroke
Front
Stroke.
Back
Stroke.
20 iV
i9Ty;
Mil"
"A*
20 &
I9H
12
20^
20"
18"
16"
14"
12"
A
H
H
H" H"
TABLE U,
Giving the Steam Port Openings of Schenectady Compound Locomotive on
Adirondack 6° St. Lawrence R. R. Cylinders, 22 in. and 32 in. X 26 in.
Drivers, 51 in. diameter. Valve travel, 5^ in. Outside Lap, % in. Inside
Clearance or Negative Lap, o in. See Mppendix R.
h. p. cyl.
Cut-off,
Inches.
1. p. cyl. '
Cut-off,
• Inches.
h. p. cyl.
Lead, Inches.
1. p. cyl.
Lead, Inches.
h. p. cyl.
Valve Opening,
Inches.
1. p. cyl.
Valve Opening,
Inches.
Front
Stroke
Back
Stroke
Front
Stroke
Back
Stroke
Front
Stroke
Back
Stroke
Front
Stroke
Back
Stroke
Front
Stroke.
Back
Stroke.
Front
Stroke
Back
Stroke.
23iV
20 X"
I7M"
I4H*
12^"
10"
23^"
20^"
i73T
I4H"
12^"
9^"
23^"
21 "
19"
17"
15"
13"
23H"
21/8"
i9Ty
i7Ty
15^"
13"
iV
1A"
A"
A"
A"
&"
iV"
y&"
jftr"
A"
£
lV
1A"
A"
1
iV"
y&"
A"
A"
iV
j\"
1%'
w
w
w
H"
A"
iH"
if
$
H"
iV
2"
ifV"
w
H"
A"
fa"
2"
if"
TV
iV
114
COMPOUND LOCOMOTIVES.
jJ-E
•\te -d
•q jo AjpEdBD oj
JO OIJEJ pJ*pUE4S
V. |
jjo-jno paBpuEjs
'£ ^
s(J9pi;ng -oooq
^ ^>
•rXo'd'u'sduio'^ joi
i^ 8
JJO-jnO IEDIUIOUOD9
4som jo uoiuido
s(j9p[ing 'dooq
; ; ; ; ; ; ; ; ; ; ; ;
*?**
•SJ9AUp
00. ... . ^ .. s^....
^3 "•N*
JO J9J9UIEIQ
$ : '. ::: *&. : : : &,'.:::
. ^°
jq3paj
^ : : : . : j : M- : g : : : :
| «
•9DIAJ9S JO pui^l
£ '. : : : : £ : £ : P^ : '. '. ':
|.{
•SUJ -Sl^DUOISUFd
9JEUIIJS9 S,J95(EJ\[
•S9qouj -d
• • • •
•§.
•j jiod jo qjSug-j
5 ^
•sgqouj -d
•q }aod jo qi3u9q
::::::: : : : : : : : : :
•S9qouj *d •[
^0 • V^O . V£ . . . .
•S g
90UEJB9p 9PJSUJ
{g |
•S9qouj -d -q
30UBJB9P 3pISUJ
::::::: * : * : °~ : : : :
^ ^
•sgqouj
•d 'i dEj apisuj
•sgqoui
^!H ^ "***
•S9qouj
W ,^. 5
<^ <o £.
•d •[ dEj gpisjnQ
H £ ^
•sgqouj
•d -q dEj apisjnQ
^ TX
•saqouj
1 1
•d '[ pAEJJ 3AIB^\
::::::: : : : : : : : : :
•d -q PAEJJ aAjE^Y
s S
ts 1
a
•JU3D J3(J
•\fo -d -j jjo-^n^
IT> IT)
•saqoui
^ Q
•jXD -d -j jjo-jn^
If
•JU30 J3J
•[Ao 'd -q jjo-jn;}
ijga^* ^ da *ft«a
i ^o
•saqoui
•§ ^
•J^D -d -q jjo-jrQ
"N CN
•S9UOUT
vO • • •
.8
•U04SI(J JO 9>(OJJS
W* ' • - - • • W • N • N • '•
%^
•S9qDUJ
'\A3 'd *J JO 'UIEIQ
N
C^ r^
•sgqoui
•[Ao -d -q jo -UIEIQ
1 t«> oo • oo • o
Giving the (
High-Pressure (
Appendix R.
' ~~ ' ^, c e J.cc J-cc
ss|1 l-sll Il1| l!ill
iy ii^i ii*| i|^£
VALVE GEAR ADJUSTMENTS,
: : :::::::::: 2 2
2
o • • • •
. . . .
• • • •
2 2
•4- -4-
0
: : : : : ° : : : 1
•V '. '.
;;;;;;;;;;;;
to
s? ! : : : LLLLJ
:::::::::::: g i £
M
S, : : : : | : : : :
•:•;:::::::; £ £ (2
fa
fe : : : : A. : : : :
o\ oo
M
. ... OO • • • •
« N N N
5
8 : : : : 8 : : : :
"\\\\\\\\\\- <? & <s
»
oo '• • • • oo • • • •
*:::::::!::: * * *
i/i ! I I ! \n '.'.'.'.
::'.:'. : : : : :
ttttttttttti ? ? *
• x
ftftl tfttj
s^
\« .... v^ ....
M ;::::;•:::: M M M
M • : : : M : : : :
O-N-t^-N-t-^-.OO SM \M \M
m.t^.Tt-.N-ON.-t^ «•?? >-R i-K
y?
^ : : : : ^ : : : :
««• • m : ro : M . N : : ^ "° * *°
^ : : : : ° : : : :
CO t^ t^vO Ot^^OOOt^t^t^ O
t>. t^\O NONOWIiOTi-Tl-iriNN Ul O
a
^?t^^^^ ^t^iSl&£
::::::::.::: 2 2
j?
>i?^tit^^ ^!^^J^^ >it V*
Kg^a$5.%8^ % -
fis
NO
$
^^«? ^?^«?
Oi
d HHH C4MMMM
. . . . ....
?:::::•:::: ? ? ?
13
"8 : : : ? : : : :
i?;;i-ii : ; ; 9. a <s
&
en • • • 8^ '. I ' '•
V2::::::::: 8 8 ?
M
8 : : : : ? : : : :
j^jjS^-S •c'S^S.S 'g'«"co'S'S"3v*"2
^"2 a o o ^^"5.5 ^^•S.Sfw wJ=-dy
.Swuw ^S1!; ^S'iSsc ^S»-S
Schenectady ^
Consolidation
Pitkin 2 cyl. tor }
Adirondack & St.
Lawrence R. R J
N e i 2 N e
50 jj ^-s^«
« 2*3 • «-^'Sw
ys^^. Ssi*'
J-gi*"j |-»,g|
S|^|| ^jr-g
5 &S S 1 15xj
n6
COMPOUND LOCOMOTIVES.
•q jo Xjpe
AjIDBdc
}O O|}BJ
•\fo -
dBD
•JA"D -d -j -sdiuoD joj
jjo-jno
-jXo -d
•q '-sdiuoD
jjo-jno pjBpuBjs
•sjsAup jo jsjsuiEia I „ : : : : &
•jqSpaj ^ : : :
JO
•3DIAJ3S jo pui^i fa : : : OH : : : : : fa : : : • fa
•suj -SIA"D uoisuEd
1°^
•d
•saqouj
•d 'q jaod jo q;3uaq
•saqDiq 'd
•j aouBJEap apisuj
•U 3DUEJE3ID 3D
•d •[ dBj apisuj
| 'd-q
t-3 -d 'i dsj aptsjhQ
W
0) ~J
•d '\ pABJJ
•saqouj
•d -q pAEaj
•jua
•jXo -d 'i
•jAb 'd -q
•jXo 'd '" Tin. in'-* *?! "$ ^-^^ "o >0s>?>>y?'« "P '^ll'o V??* ^ ^
J°_
•d •! jo9-uiBlg| $ ; : : g»
•d -q jo -UIBIQ I 8 : : : : 8 ' : : 8 : : : : : S
2N E
On:
VALVE GEAR ADJUSTMENTS.
117
A - A
2 is
!
$
c?
*: £
3R
^
at
vo m
\o »n
in mm
m m
STS-s^s/RoSS 5-v?<g
& «?
^ : : : : :
as* ^
S^
. . 2 ?? 8 ff
c
1 M M
« M • • • •
N • • « S
N N
M M
M 00 • • • •
8* ' ' ro 8*
8* eT
& °S
v^ • • • •
N{J
N M . . . .
I-2!
^S «c« tfjpS «&•« >O >
« D««a
n8
COMPOUND LOCOMOTIVES.
•[Ao -d
•q jo XipEdEO oj
AlIDEdED J3AI3D3J
JOOIJEJ pJEptlElS
s^apjing •ooori
ll ll | |
« ^ .« ^ ^ ^
rt rt 0 0
> > z z
•[Ao "d 'i ''sduioo joj
jjo-ino pJEpuEjs
•JAD
•d 'q ' -sduioo joj
% % ; II 1 M 1 1 1 1 ; 1 1 1 1 1
sjapjing -oooq
;;•.;;; I " ! I I I ! r I !
•SJ3ATJp JO J9J3UIEIQ
t^ m in .' I I I I mil'.'*'.'.'.'.'.
•jqSpjj
JO J38U3SSB(J
« r £::::: £ :.•;:;:::
•9DIAJ3S JO pUI}J
f*». * *::::: *:::::::::
•SUI -S|Ab UOtSUEd
-X3 3[3u;s jsnba
^4 CJ ...
x x . :::::: ::::::::::
~ ° ..::::•;::
•saqouj
•*• •*• •««••
•d q jjod jo qj3ua^[
•saqouj
•d 'q jjod jo q;3ua^
N M H .'.'..'.'.'.'.
•saqouj -d
•| 3DUEJE3p 3pISUJ
o o
1
•saqouj *d
•q aDUEJEap apisui
^ fr> '.'.'.'.'.'. '.'.'.''.'.'.'.'.'.
"•§
•saqouj
«jj
»
•d •[ dE[ apisuj
: : :::::: ^ :::::::::
r^j
•saqouj
N
1
•d -q dEi apisuj
: : :::::: «:::::::::
M
•saqouj
•d 'i dEj apisjnQ
^ ^ :::::: » :::::::::
s
•saqouj
•d -q dEj apisjnQ
? * |||::| ^1 I I I I I I I I
—
•saqouj
•d 'I pABJJ 3A]E^
\O VO ^
•saqouj
ist :::::: ^ :::::::::
'd -q |3AEJJ 3A[E^
10
•JU3D J3J
'l^o -d 'i jjo-jn^
& * :::::: ::::::::::
•saqouj
* H M wM"MN5« NOIMNNNN^MM'
•jXo *d 'q jjo-in^)
% 1 :::::: :•::::::::
•saqouj
•jXo -d 'q jjo-4ir)
0,0.^0=0 ^HvO^^S
M H
•saqoui
•UOJSIJ JO 3>IOJJS
"S cf ?::::: S":-::::-:
•saqouj
^j* ^
•jAo -d -j jo -UIEIQ
S" M &'.'.::: R ::':::::
•saqouj
•^ ^*
•t^o -d -q jo -UIBIQ
S & ?::::: J? : : : : • • : I :
JV^ ^ A A
c*o >> jr »: • fc'rt'a ' *o • »- rs
«x u ^2 c^= ^2 £ « x c c o 2
<uO . s _ 5 o ^. £ JWO ,«^: •"
"1 c ^ ^ f « "^ n O l~> u • "Si J __. «^
VALVE GEAR ADJUSTMENTS,
IIQ
*
v«
120
COMPOUND LOCOMOTIVES.
•IAD -d
>sdt
•q jo AjpsdED oj
jo OIJBJ
-oooq
lAb -d 'i
jjo-jno
stapling 'oooq
•d *q '"sduioD aoj
jjo-jnD paupuujs
stapling -oooq
SJSAUp JO J343UIBJa o
JO J33U3SSB,J £*
•aoiAjas jo pui^ "
•suj -s
-X3 ajSuis
JO 9)EUII)S3 !
•d •[ jjod jo qjSuaq | %
•saqoui
•d -q jaod jo qjSuaq
-saqoui -d
*§" -saqoui -d
S -q 3DUEJE3P apisuj
•d -j dEi apisui | °
-saqoui j
•d -q dB[ apisuj | '
•saqoui I ^
•d 'i dEj spismo I
•d -q dEj aptsjnQ |
•saqouj I
•d -q PABJJ
•1
.•JAO -d
•JAO -d -q Jjo-m3
•saqou!
•\fo "d -q jjo-vn3
•saqoui
•{Xo 'd '[ JO "UIEIQ
•[Xo -d 'q jo 'uiBiQ
VALVE GEAR ADJUSTMENTS,
121
TABLE V.
Showing the Change in Exhaust Closure Affected by Using Inside Clearance
or Negative Lap. Taken from a Schenectady 10 Wheeler on the Michigan
Central R. R. 19 in. X 24 in. Single Expansion Engine and 20 and 29 X
24 in. Compound Engine. See Appendix R.
Negative
Lap or
Clearance,
Inches.
Cut-off,
per cent.
Compound.
Single Expansion.
Release
of Steam
per cent,
of Stroke.
Compres-
sion
of Steam
per cent,
of Stroke.
* Valve
Travel and
Outside
Inches.
Release
of Steam,
per cent,
of Stroke.
Compres •
sion
of Steam
per cent
of Stroke.
Valve
Travel and
Outside
Lap,
Inches.
•J
•f
"I
«l
33
41.7
50
58-5
83-5
33
41.7
50
58-5
83-5
33
41.7
50
58.5
83.5
33
41.7
50.
58.5
8*.S
74-4
78.1
81.2
84.4
94-8
70.8
73-5
78.1
81.2
93-7
67.1
70.8
75-5
79-7
92.9
63.0
67.7
72-9
77-6
QI.Q
80.0
82.9
85-4
88.5
96.3
82.3
85.4
87.5
89.6
96.9
86.1
88.0
90. i
92.2
97-7
88.0
90.1
92.2
93-8
Q7.Q
6K
I#
6K
i^
6^
ilA
6K
I*
62.5
66.7
73.9
79-2
92.7
80.2
82.3
87.5
90.6
96.9
5M
%
CHAPTER XII.
MAIN VALVES.
77. Lap, Travel and Size of Ports. — The dimensions
of the steam ports, valve travel, and outside and inside
lap, suitable for compound locomotives, do not differ much
from the best practice for single expansion locomotives, but
it has been abundantly proved that better valve motions are
needed for compound locomotives than are ordinarily
used for single expansion. Also the valves and ports should
be always in proportion to the cylinders, and this gives to
the valves of the 1. p. cylinders very large dimensions. The
largest port in common use a few years since was 19 inches.
Now the 1. p. cylinders of compound locomotives have ports
24 inches long. Probably the compulsory use of longer
ports and larger valves has had more to do with the recent
tendency to use piston valves than any other factor. Large
slide valves of the ordinary D form are very difficult to bal-
ance satisfactorily, and they cause a much increased wear on
the eccentrics and links.
78. Piston Valves. — Piston valves are necessarily baU
anced from the nature of their construction, and certainly
have been shown to be quite as applicable to locomotive
work as to marine work, where they are now so commonly
used. With a piston valve a very long port is readily ob-
tained, and in fact a larger port is necessary, as the same
length of port on the circumference of a piston valve is not
as effective as a rectilinear port of the ordinary form with
a flat valve.
Two express locomotives with piston valves have been
built by Mr. von Borries for the German State Railroads.
The experience with these engines shows that a piston valve
MAIN VALVES. 123
must be considerably longer in circumference, which is in
reality the length of the port, than is required with a flat
valve to give equally good admission of steam. Ample
room must be provided for the approach of steam to a piston
valve or the advantage of its longer port will not be gained.
Piston valves should have the same travel, and inside and
outside lap as the ordinary form of D slide valves. The
piston valve is, in fact, only a slide valve rolled up to form
a cylinder, and needs the same treatment in design.
79. Some Effects of Inadequate Valve Motions.—
The greatest evils which have to be met in arranging
steam valves for compound locomotives are those of wire-
drawing and compression. The wire-drawing in the h p.
cylinder is practically no worse, nor more detrimental, than
in a single expansion engine, but wire-drawing into the 1. p.
cylinder causes additional loss, and interferes with the
adjustment of the power between the cylinders by means of
the cut-off. In some compounds already built the wire-
drawing through the main valve for the 1. p. cylinder is so
great that the cut-off point is not perceivable on the indi-
cator card, and the engine works in about the same way as
the old fashioned stationary engine with a throttle governor.
Compression causes more loss of power and efficiency in
the h. p. than in the 1. p. cylinder on account of the higher
back pressure. In the 1. p. cylinder the absolute back
pressure at the time of exhaust closure is not far from 20
pounds, and with five compressions the terminal pressure at
the end of the stroke would be not far from 100 pounds
absolute. But in the h. p. cylinder the absolute back pres-
sure is ordinarily about 65 pounds and with five compressions
the pressure at the end of the stroke in the h. p. cylinder
would be nearly 300 pounds, or very much above boiler pres-
sure, 6. What actually does occur is this : when compound
locomotives with the ordinary valve gear are running at a
short cut-off and at high speed, the compression in the h. p.
124 COMPOUND LOCOMOTIVES.
cylinder rises to a point above the boiler pressure, where it
lifts the main valve, and the excess of steam in the clearance
spaces and ahead of the piston is pushed into the steam
chest. This will be observed in Figs, n, 12, 14, 15, 112,
113, 127, 136 and 149.
Whether a piston valve, or a slide valve of the ordinary
kind is used, the simplest way to reduce wire-drawing and
compression after making the ports as long as is practi-
cable, is to increase the valve travel, increase the outside
lap, and cut out the valve on the inside to give what is called
"clearance" or "negative" lap. See Table Ui.
The effect of increasing the valve travel and outside lap,
is to give a greater port opening at short cut-offs and to
postpone the point of compression toward the end of the
stroke, thus reducing compression. The effect of cutting
out the inside of the valve to make a negative lap is to delay
the closure of the exhaust and reduce compression.
80. Effect of Long Valve Travel and Inside Clear-
ance or Negative Lap. — The following will illustrate the
benefit obtained from a change in valve travel, outside lap,
and from the use of inside negative lap: A 5^ inch travel
with ^ outside lap will give about -^ inch port opening at
25 percent, cut-off. A 7 inch travel and i% inches outside
lap will give nearly y2 inch port opening at the same cut-off.
fyfa inch negative lap will reduce compression to a point
somewhat below the admission pressure, which is where it
should be, when used on an engine which formerly had
positive inside lap, and a compression much above
boiler pressure before the completion of the stroke. 7
inches valve travel on a locomotive is not so great as to
lead to any mechanical difficulties in operation or
design. This has been conclusively shown by the experi-
ence of Mr. L. B. Paxson, S. M. P., of the Philadelphia
& Reading Railroad, Figs. 39 to 42, and by the experi-
ence of the Rhode Island Locomotive Works. These two
MAIN VALVES. 125
companies have led in this country in the matter of long
valve travel. As much as ^ inch negative lap on each side
on the h. p. cylinder has been used with success on high
speed compound locomotives. ^ inch negative lap on each
side has been used with success on the 1. p. cylinder. -^
inside negative lap has been used with excellent results on
single expansion locomotives, and the experience already
had shows beyond doubt that inside clearance is absolutely
necessary on all high speed locomotives, whether single
expansion or compound, if the best results are desired. It
is practically impossible to design a high speed compound
locomotive, no matter what the type, that will run without
excessive wire-drawing and compression with the Stephenson
link motion or with any of the commonly used locomotive
valve gears, without using a long valve travel and considerable
inside clearance or negative lap for both cylinders. The
greater amount of negative lap is needed for the h. p. cylinder.
The effect of inside clearance or negative lap on steam
distribution at various low speeds, and the effect it has on
the shape of indicator cards, is shown by Fig. 43, indicator
cards Nos. I to 6. The data for these cards is given in Table
W. It will be noticed that at low speeds the steam from
the exhaust of one end of the cylinder passes over into
the other end of the cylinder through the opening that is
made between the two ends of the cylinders by the use of
negative lap. The negative lap in this case was -^ and T36
inches. From card No. 6 it is clear that this transfer of steam,
at the time of exhaust from one cylinder to the other, dis-
appears almost entirely when speed has increased to 32.5
miles per hour. These cards also show that the engine from
which they were taken had liberal steam pipes and passages,
as the steam chest pressure and receiver pressure varies
but little from the pressure at admission. These are admir-
able cards from a compound locomotive for the speed at
which they were taken.
126
f
COMPOUND LOCOMOTIVES.
FIG. 39.
Inch Inside Lap.
FIG. 40.
Inch Negative Lap.
6
FIG. 41. FIG. 42.
Inch Inside Lap. 1A Inch Negative Lap.
Indicator Cards Showing the Effect of Negative Lap.
MAIN VALVES.
127
B.Pt
63
5 _.
No 61
No 50 £,
No 76
FIG. 43.
Indicator Cards from Compound Locomotive Showing Effect of
Negative Lap at Low Speed.
128
COMPOUND LOCOMOTIVES.
TABLE W.
Giving Data about Indicator Cards Nos. i to 6, Fig. 43, from Schenectady
{Pitkin} Compound on the Michigan Central Railroad. See Appendix R.
Number of
Card.
Revolution
per minute.
Miles an hour.
Cut-off in Inches.
H. P. L. P.
I
40
6.8
21% 22%
2
72
12.2
17 isy&
3
104
17-6
13^ 151^
4
108
18.3
12 13}^
5
104
I7.6
10% I2^i
6
192
32-5
10% I23/&
Length of Valve Travel 6^ in. full gear.
" Steam Ports, 1. p. cyl. - 20"
" " " h. p. cyl. - 18"
Width of " " 1. p. cyl. - 2%"
" " " " h. p. cyl. - 2^"
Outside Lap, h. p. cyl. - - - i%"
Inside Clearance, h. p. cyl. - - tV
Outside Lap, 1. p. cyl. - - il/%"
Inside Clearance, 1. p. cyl. ... T^"
Giving data regarding Figs. $g and 41, cards Nos. i to 6, taken from a
Philadelphia &* Reading express engine, with Single Expansion cylinders.
c
3
cr!
w •
«; O
u
a
6
o
•|M
•g g
sj1"1
"1
.2 £
5
C
W u
I S
a""1
J «
"Sji
S5
'5 B
&
S:
^ is
w S .
hJ W
^"n .
0 ?
"S
03
Jl
1
a
« «
c u"H
15
|*|
1^
0
i
0
^
S
c
c
DH
I
136
27.7
Full stroke.
106.8
109-35
6\
....
Wide open.
2
262
53l3(T6T)
6/^
45-75
50-4
^¥
....
'
3
280
57
6^
49-2
55-8
fa
....
'
4
294
59i8<$y
6/^
39-45
44.1
fa
....
1
c
282
r>7_4 4
33* J9
I
<
D
6
294
59^4
4
32-65
35-55
A
....
'
The small effect of a little inside clearance or negative
lap is very clearly and satisfactorily shown by Figs. 39, 40,
41, and 42, indicator cards Nos. i to 6, which were taken
from a 21 x 22 inch Philadelphia & Reading express loco-
MAIN VALVES.
129
TABLE Y.
> K
Giving data regarding Figs. 40 and 42, cards Nos. i to 7, taken from a
Philadelphia 6° Reading express engine, with single expansion cylinders, and
showing the small effect produced by a little inside clearance or negative lap, also
showing the need of much inside clearance, and showing also the slight effect on
steam distribution produced by inside clearance at slow speed.
£
8,
|
«
1
ll
|l
•si
1-
1
s
§ '
ffi
Is
^ S
ft1""1
S ^
•*0
3
25
j=l
a
^
w =
c ""
W IT,-
^1
UT3
c
1
Ji
1
II
Sc£w
12*^
1*0 -g
'!•='
U
S
w
S
*
•-1
•-1
OH
I
119
24
Full stroke.
IIO.IO
107.25
X
Wide open.
2
264
53y7^
6^
55-8
48.
/^
"
3
282
57TV<r
6K
53-25
54-75
X
"
4
294
59T808(T
6/^
43-5
42.75
X
4<
5
318
64lVT5
4
42.6 '
38.55
X
"
6
324
^SlVlT
4r
36.15
26.40
X
"
7
348
7°A%
45-
44.4
K
"
FIG. 44.
Good Steam Distribution in Single Expansion Locomotive Cylinders.
motive. The normal boiler pressure is 145 pounds by gauge.
Tables X and Y give the data about these cards. This
engine is unusual in having 7 inches valve travel and I ^ in.
outside lap. Probably these indicator cards are the best
ever taken from a locomotive with a Stephenson link
motion. The good points of such a card as No. 7, Table
Y, Fig. 44, taken from this engine with % mcn negative
lap, at 70 miles an hour show how difficult it will be for a
compound locomotive to make a saving in passenger service
against a locomotive having long valve travel and inside
clearance and ample area of steam and exhaust ports. The
effect of using inside clearance on the distribution of steam
I3O COMPOUND LOCOMOTIVES.
at slow speed is very small, as is clearly shown by a com-
parison of Figs. 39 and 41, with Figs. 40 and 42. These
cards, taken with the throttle full open, show that consider-
able inside clearance is needed to produce a substantial
benefit at high speed with long valve travel. The ^ inch
inside clearance used on this engine would have shown a
more substantial change in mean effective pressure at high
speed- if the valve travel had been 5^ inches, as is common
on locomotives. The new compound locomotive designed
by Mr. Axel S. Vogt, Mechanical Engineer of the Pennsyl-
vania Railroad, has ^ inches inside clearance in the h. p.
cylinder and $/% inches in the 1. p. valve, and 7 inches valve
travel.
81. Conclusions about Main Valve Dimensions. — It
is impossible to give a general rule for the area of steam
ports and valves of compound locomotives. What can be
said that is useful is : the valve travel should be as long as
it can be made without inducing mechanical difficulties. It
probably should never be less than 6 inches and would
better be 7 inches. The inside clearance or negative lap
should be what is necessary to reduce compression, and the
increase of the negative lap should be carried on until the
indicator cards from the engines under normal conditions
are comparatively satisfactory in the matter of compression.
If there is any waste due to negative lap, it will show on
the indicator card, and can be estimated therefrom and in no
other way except by an elaborate shop test. There is a tra
dition among railroad men which has operated against the
proper use of negative lap. This tradition is to the effect
that inside clearance causes a waste of steam, but this
tradition is not founded on fact and is true only for very
slow speed locomotives.
In conclusion, about all that can be said to assist the
designer is that the best modification that can be made of
the common form of link motion will be none too good for
MAIN V'ALVES. 13!
compounds, and it is well worth while to pay a considerable
sum to get long valve travel and large steam ports. If the
steam ports are made the same length for both h. p. and
1. p. cylinders and are made considerably longer than the
diameter of the h. p. cylinders, say 20 per cent, and the
valve travel for the common sizes of locomotives is made
from 6y2 to 71^ inches, and the negative lap about ^
inches for freight and ^ inches for passenger for the 1. p.
cylinder, and ty& of an inch for freight and ^ inches for
passenger for the h. p. cylinder, the practical results from
service will be pretty nearly satisfactory. If the compres-
sion with these proportions is too great, as it may be for
high speeds, the negative lap must be increased. If there
is too much wire-drawing, there is only one recourse with
the Stephenson link, namely, to increase valve travel and
the length of the ports. Of course, the supplementary
or Allan port is an advantage, but does not give as much
benefit as an increase of valve travel. To add an Allan
port to long travel valves sometimes causes trouble in
design, as the valve must be longer and the area to be
balanced will be larger. Allan ports for piston valves are
scarcely practical, as the same effect can be gained by
making the valve with a larger diameter, and this is easier
and simpler than to introduce the additional packing rings
for the Allan port. In these remarks all consideration of
the unusual forms of valve gears so far tried have been
omitted for the reason that none of them have proved to be
what is wanted for practical work.
CHAPTER XIII.
STEAM PASSAGES — ACTION OF EXHAUST.
82. Size of Steam Passages and Loss Due to
Wire-Drawing. — All of the rules applicable to the use of
steam, so far as steam passages are concerned, that are
common in stationary engine work apply with equal force
to locomotives. Formerly it was a common defect in loco-
motives to have too small steam passages, but now a few
of the modern designs have the same area of passages as
are provided for stationary engines. When this is done,
and the engine is run with a wide-open throttle, the
difference in pressure between the boiler and the steam
chest will be very small, even when the locomotive is run-
ning at considerable speed. See Figs. 43, 46 and 47.
The loss due to running a locomotive with a partly open
throttle or with too small steam passages is more than is
generally understood, as has been recently proved by the
shop tests of a locomotive by Professor Goss at the Purdue
University. Diagram, Fig. 45, shows in a general way what
these results indicated. Such wire-drawing as is shown on
the diagram gave considerable super-heat to the incoming
steam, but the reduction in cylinder condensation due to
super-heat did not offset the loss in potential of steam
pressure. Therefore, it may be concluded that locomotives
should have large steam passages and be run with a wide-
open throttle ; more particularly is this true of the com-
pound locomotive, which depends for its economy upon the
utilization of the high potential of increased steam pressure
by giving greater expansion.
132
STEAM PASSAGES— ACTION OF EXHAUST. 133
. so
I
a*
i
$
^4 30
O
\o
O ^>-
J)!?] PIPE PRESSURE
FIG. 45.
Diagram Showing Loss of Efficiency Due to Wire-Drawing Through Throttle.
FIG. 46.
Indicator Cards Showing Difference Between Boiler, Steam Chest
and Initial Pressures.
134
COMPOUND LOCOMOTIVES.
FIG. 47.
Indicator Cards Showing Difference Between Boiler, Steam Chest
and Initial Pressures.
FIG. 48.
Indicator Cards Showing Effect of Small Nozzles on Back Pressure.
See Table AA.
STEAM PASSAGES— ACTION OF EXHAUST.
135
The variation in steam chest pressure of locomotives,
where the throttles are of proper dimensions, and the steam
pipes and passages are adequate, is shown by Figs. 46 and
47, Cards Nos. I to II, Table Z, which were taken from
a 1 6 X 24 passenger engine on the Chicago, Milwaukee and
St. Paul road. The small drop between the boiler and the
TABLE Z.
Showing the Variation in Steam Chest Pressure on a Single Expansion
Locomotive, illustrating the comparatively small drop between the Boiler and the
Steam Chest at a speed not exceeding 45 miles per hour, when the throttle is wide
open. See Figs. 46 and 47.
j
1.
-^
llf
|| i,
ft
ss
§
1
g^
i
E -
Js
J3
5C "c
tc "c
c
o
8
sg
a
1
Tl
fl
|J3
8 5! . B
S S c
c
rt
JS
c >
^ So
a
di
0*2
^ 3
§
fS |
^1
w
w
(^W w*
fiiw sr
S
w
^
i
2^
3
37-4
42.0
132
24.2
254
141
2
4/8
29.4
29.2
240
44-2
338
120
3
5iV
5%
42.6
45-4
172
31-7
362
141
4
7%
55
58-4
152
28
412
148
5
6^
7X
54-2
1 68
3i
422
145
6
8
8%
55-2
57-4
192
35-4
518
145
7
8
8/4
65.6
68.
148
27-3
479
I46
8
8
8/4
49
51 .
204
36.5
489
140
9
9^
10
57-6
61.
140
25-6
398
I42
10
I0if
H^
85
88.4
1 08
20
448
M7
ii
I2#
I2T9e
73-8
74-8
1 68
31
599
138
steam chest in this case is due to a wide-open throttle. At
high speeds the drop increases somewhat depending upon
the cut-off and the size of the passages, but these cards
show what may be expected in fairly well designed loco-
motives at a speed not exceeding 240 revolutions per
minute, which in this engine amounts to about 44 miles per
hour. The engine is a 16 X 24 inch cylinder, five-foot
wheel passenger locomotive of the eight-wheel American
type.
83. Effect of Exhaust on Fire and on Back Pres-
sure.— The lower pressure and greater volume of the
exhaust from the compound locomotive appears to produce
136
COMPOUND LOCOMOTIVES.
a more uniform and a better effect on the fire. This
advantage, added to the decrease in the total fuel con-
sumption per minute, resulting from the saving of the
compound, has, so far as can be seen, caused a secondary
saving of fuel due to compounding. There are, then,
perhaps, two savings due to compounding. The primary
saving due to the compounding per se, and the secondary
resulting from the better action of the draft and the
decreased forcing of the fires, 142.
In suburban or elevated railroad service, where mufflers
are put on the exhaust pipe of single expansion engines to
decrease the noise of the exhaust, the use of the compound
locomotive, with its lower pressure of exhaust, enables the
mufflers to be dispensed with. In this way as much as 20 per
cent, of steam may be saved by the reduction of the back
pressure in the cylinders caused by the mufflers. Mufflers
clog up quickly and have to be bored out frequently, or the
back pressure becomes so great as to make the engines
"logy," 139-14:7.
TABLE AA.
Back Pressure Before Changing Valves and Nozzles.
No. of
Card.
Speed.
Miles
per hour.
Cut-off.
Boiler
Pressure.
Pounds.
Initial
Pressure.
Pounds.
Mean
Effective
Pressure.
Pounds.
Mean Back Pressure includ-
ing Compression. Pounds.
4
15-
12"
160.
151.
98.
20.5
I
24.
9"
160.
ISO.
79-
22.5
2
30.
8"
160.
143.
57-
25-5
5
35-
8"
I58.
135-
5i-
27.
3
42.
8"
1 60.
150.
57-
31-5
6
53-
5"
160.
146.
39-
28.
Figs. 48 and 49 show the need of very carefully watch-
ing the details of a new design of engine, by examining
indicator cards, to prevent losses in the cylinders by
back pressure. Fig. 48, Indicator Cards Nos. I to 6, see
Table AA, gives the back pressure in a ten-wheel engine
with a 3^ exhaust nozzle double, that is, with a separate
nozzle for each cylinder. The nozzles were increased in
STEAM PASSAGES— ACTION OF EXHAUST.
137
diameter -J of an inch, and the inside lap was cut out from
^ig on both sides to -^ negative lap on both sides. The
decided reduction in back pressure, as shown by Fig. 49,
Cards Nos. I to 6, and by Table BB, changed the engine
BP
a './?
FIG. 49.
Indicator Cards Showing Decrease of Back Pressure Following an
Increase of the Diameter of Exhaust Nozzle. See Table BB.
TABLE BB.
Back Pressure after Changing Valves and Nozzles.
No. of
Card.
Speed,
Miles per hour.
Cut-off.
Boiler
Pressure,
Pounds.
Initial
Pressure,
Pounds.
Mean
Effective
Pressure.
Pounds.
Mean Back Pressure includ-
ing Compressions. Pounds.
I
18
10"
158
MS-
98.
9-5
4
24
9"
1 60
MS.
75-
16.
2
29
8"
158
143-
66.
17.5
5
33
8"
155
138.
58.
18.5
3
42
8"
155
137-
52.
24-5
6
54
5"
155
130.
40.
23-
materially. The difference was enough to make quite a
saving in fuel. Such a change as this in back pressure
produces the effect on an engine that is known to loco-
motive engineers as "smarter," that is, the engine has a
livelier action.
138 COMPOUND LOCOMOTIVES.
Fig. 49a illustrates how the mean effective pressure is
effected by an increase or decrease of back pressure. The
two sets of cards shown are those numbered 5 in Tables
AA and BB. The space between the cards that is sec-
tioned by vertical lines shows the change in mean effective
pressure brought about by a variation in the back pressure.
It is evident from this illustration that the effect of an in-
crease or decrease of back pressure extends over the entire
FIG. 49a.
Effect of Back Pressure on Mean Effective Pressure.
length of the indicator card. The reason of this is that
when the back pressure is increased or decreased the pres-
sure at the commencement of compression is correspond-
ingly increased or decreased, and the whole compression
curve is therefore effected. The conclusion from an exam-
ination of Figs. 48, 49 and 4ga must be that a careful selec-
tion of exhaust and draught apparatus is necessary in order
to produce an economical and powerful engine at high
speed.
CHAPTER XIV.
EFFECT OF HEAVY RECIPROCATING PARTS.
84 Weight of Reciprocating Parts. — It is of the
utmost importance that the weight of the pistons, cross-
heads, piston rods, main rods, and in fact all the reciprocat-
ing parts of a locomotive be kept down to the lowest limit.
The reason is that these parts have to be balanced to make
the engine ride steadily, and this balance acts at all points
of a revolution of the drivers. It has an outward or
centrifugal tendency from the centre of the .wheel that is
very great at high speed. This tendency of that part of the
balance that is used for the reciprocating parts is counter-
acted only when the balance is in the horizontal position,
that is, when the crank is at the end of the stroke. At
other times the centrifugal tendency is upward or down-
ward, and is unresisted except by the rail or the springs
above the axle boxes. This centrifugal tendency is some-
times so great as to lift the wheel from the rail. And it
has in some cases seriously damaged the tracks during a
single run by a badly balanced locomotive at high speed.
It is then necessary to reduce the weight of the recipro-
cating parts, and thereby the reciprocating balance as much
as possible. Unfortunately compound locomotives carry
with them a necessity for larger pistons. These large
pistons will of course be heavier than smaller ones, but are
not necessarily heavier than those that are now commonly
used here for single expansion engines. In the United
States builders are much behind European practice in
piston and crosshead construction. The weight of the
reciprocating parts used here is more than twice as great
139
I4O COMPOUND LOCOMOTIVES.
as those used in Europe for the same size of cylinder. This
results from the use here of a cheaper type of piston. The
foreign type is generally of forged steel with a single plate.
Here they are generally made of cast iron with double
plates. By using some of the higher grades of manganese
steel, or aluminum bronze, or by using forged steel, the recip-
rocating parts of either a two-cylinder receiver compound or
a four cylinder non-receiver compound would not weigh
more than the reciprocating parts of some of our present
single expansion engines.
A commendable step that has been taken in the reduction
of reciprocating parts is the removal of the non-useful weight
in the Vauclain crosshead by the Baldwin Locomotive
Works. This is shown in Fig. 119. This crosshead is
made of cast steel and cored out to remove all weight
possible. Such reduction of weight is possible in all
American types of crossheads, and a similar reduction is
possible with American pistons. By devoting as much
attention to reduction of weights and reciprocating parts as
the matter deserves, the total weight might be reduced at
least 50 per cent.
85. Advantage of Large Drivers. — Large drivers
reduce the number of revolutions per minute, and thereby
decrease not only the piston speed, but also the effect of
the counterbalance weight, and therefore a large wheel is
advantageous for a compound, as it reduces the wire-draw-
ing and compression in the cylinders, and decreases the
effect of reciprocating parts. See Fig. 50.
•86. Counterbalancing of Reciprocating Parts.—
Counterbalancing is a matter that requires especial attention
in selecting a compound. Only the lightest practical re-
ciprocating parts should be used, and the practice followed
in high speed marine work will serve as a guide.
87. Marine Practice in Counterbalancing. — There
are large triple expansion marine engines running at piston
EFFECT OF HEAVY RECIPROCATING PARTS.
141
speeds of over 800 feet per minute. The piston speed
attained by the quadruple expansion engines of the torpedo
0000
0000
60000
5000O
40000
30000
20000
10000
20
4O 6O 8O
SPEED IN MILES AN HOUR.
1OO
FIG. 50.
Diagram Showing Decrease in Pressure on Track Due to Counterbalance
Which Follows an Increase in the Diameter of Drivers.
boat "Gushing" was 925 feet per minute on her trial, and
the speed of pistons of the triple expansion engines of a
142 COMPOUND LOCOMOTIVES.
recent Turkish torpedo boat is given as 936 feet per minute
on a trial trip. If these speeds are practicable with triple
and quadruple expansion engines, there does not appear to
be any good reason for doubting the practicability of speeds
of 1,100, or even 1,4.00 feet, with compound locomotives.
There is undoubtedly a maximum limit to piston speed,
and it is lower for compound engines than for single ex-
pansion engines, but the limit is sufficiently high to be com-
paratively unimportant to the designer of locomotives.
The principal factor which limits the speed is the weight
of the reciprocating parts. In an engine working at a
speed of 250 revolutions per minute, the reciprocating
parts must be started from a state of rest at the beginning
of each stroke, and their speed accelerated to about 26
feet per second during approximately a half stroke, which
occupies about 0.06 second. A very full and complete
discussion of this subject will be found in a paper by Mr,
D. S. Jacobus, in Vol. XI. of the Transactions of the Ameri-
can Society of Mechanical Engineers. See Appendix P.
The pressure per square inch of piston, for a locomotive
having a cylinder 18^ inches in diameter and 24 inches
stroke, required to overcome the inertia of the reciprocat-
ing parts and accelerate them at 250 revolutions per
minute, varies from about 55 pounds at 10 degrees from
the dead point to o at about 80 degrees. The work stored
in the reciprocating parts during the first half of the stroke
is, of course, transmitted to the crank pin during the last
half of the stroke. But the effective pressure on the crank
pin during the first half stroke is only that due to the differ-
ence between the apparent pressure as shown by the indi-
cator card and that necessary to accelerate the reciprocating
parts. It is evident that if the pressure of the steam on the
piston is just equal to that required for acceleration at
any position of the piston, no pressure will be transmitted to
the crank pin at that point in the stroke, and that if these
EFFECT OF HEAVY RECIPROCATING PARTS.
143
pressures are equal during the period of acceleration, all
pressure which is transmitted to the crank pin during the
stroke will be during the second half stroke.
The pressure necessary to produce acceleration varies
directly as the weight of the reciprocating parts, and as the
square of the speed of rotation. The possible means of
reducing this pressure are therefore to make the reciprocat-
ing parts lighter, or the driving wheels of greater diameter
O 2O 4O 6O
SPEED IN MILES AN HOUR.
FIG. 51.
Diagram Showing Difference in Counterbalance Pressure on Track in
American and Foreign Engines.
so as to reduce the speed of rotation. How much the
distribution of pressures on the crank pins will be affected
by such changes is a question which must be solved by the
designer in each case, and it is a factor which is worth
careful consideration, more on account of the crank-pin
pressures than on account of the limitations of speed. A
considerable reduction in weight is effected by the use of
144
COMPOUND LOCOMOTIVES.
steel, wherever practicable, for the reciprocating parts, and
the adoption of the most economical shapes for connecting
and coupling rods, pistons and cross-heads.
88. Effect of Decreasing Weight of Reciprocating
Parts and Increasing Diameter of Drivers. — Fig. 51
gives the maximum pressure on a rigid track due to that
portion of the counterbalance of a locomotive that is used
to counteract the horizontal effect of the reciprocating parts
of American and foreign locomotives of the same size of
cylinder. This diagram also illustrates the reduction of
the variations of pressure of driving wheels upon the track
P 20
SS 40
$ eo
K ao
too
>
j
/
^
\
"f
>.
\
u.
/
\
DP
PiR
FF
OF
^F
/n
ir
'IP
^
3
G
o
9O
'
r°
TO
1
to
-;
a
10
Z
0
a
V)
a
10
•*
0
J9o
?
L'<
"1
Y-.
E
/
f^
;<;
•H
\
•
L
-.1
|
.
A
y
0
\
L<{
>
\
7
/
\
*
I
E£
FIG. 52.
Diagram Showing Distribution of Counterbalance Pressure over Track
and the Per Cent, of Maximum Centrifugal Pressure Which
Occurs at Different Points of a Revolution.
that follows an increase in the diameter of the driving
wheels and a reduction of the weight of the reciprocating
parts.
Fig. 50 shows the advantage of a large wheel in reduc-
ing the centrifugal tendency. The pressures given are
all calculated for an engine with an 18 X 24 cylinder
89. Distribution of Centrifugal Tendency of Counter-
balance over the Track. — Fig, 52 shows the variation in
the per cent, of the maximum centrifugal tendency of
counterbalance, which is exerted on the track at different
EFFECT OF HEAVY RECIPROCATING PARTS. 145
points during a complete revolution of the driving wheels
when the track is rigid and does not deflect under the load
due to the centrifugal tendency. It also shows how the
maximum track pressure is distributed over several ties, and
how it gradually increases and decreases.
CHAPTER XV.
DESCRIPTION OF TWO - CYLINDER RECEIVER COMPOUNDS
WITH AUTOMATIC INTERCEPTING VALVE STARTING
GEARS, AND WITHOUT SEPARATE EXHAUST FOR HIGH-
PRESSURE CYLINDER AT STARTING.
The inauguration of the present era of compound loco-
motives in Europe is due to Mr. Anatole Mallet, who
designed successful two- cylinder compound locomotives
for the Bayonne & Biarritz Railroad in 1876, and has since
brought out many different designs. While it would not be
incorrect to class the greater number of compound locomo-
tives as belonging to the Mallet system, this term as applied to
two-cylinder engines is usually restricted to those which can
be operated either as single expansion or compound engines
at the will of the engineer (non-automatic) as distinguished
from those which are necessarily worked as compound
engines, except for a brief interval in starting (automatic).
The disposition of cylinders and steam chests with
regard to the boiler and running gear of two-cylinder com-
pound locomotives does not differ from the practice in
single expansion locomotives. The same diversity of de-
sign that has heretofore been remarkable in European
practice as compared with the American, is found in com-
pound locomotives. The designer will find precedent in
existing engines for almost any arrangement of principal
parts and for any type of valve gear which he is likely to
adopt.
There have been quite a large number of inventions of
somewhat minor value in the details of starting gear, more
particularly of the automatic type, for two-cylinder com-
pound locomotives, and a number of patents have been taken
146
TWO-CYLINDER RECEIVER COMPOUNDS. 147
out in this and foreign countries, but as a rule they differ
so little from the original designs of Mallet and von Borries
that the patents are weak and the scope limited to some
specific construction. It is impossible to give within the
limits of these pages anything like a complete resume of
the art at this time as exhibited in the Patent Office. It is
not useful to do so, as the reader would be confronted with
a mass of drawings and descriptions which would lead to
no conclusions. Only the principal designs and such as
have actually been put into service are here described.
90. The von Borries System in 1889. — This system
is strictly automatic, which means that the change from the
use of boiler steam in the 1. p. cylinder to full compound
action is made automatically without the will of the engineer,
and takes place whenever the accumulated pressure of the
exhaust from the h. p. cylinder in the receiver is sufficient
to operate the automatic mechanism. Figs. 53 and 54 illus-
trate one of the arrangements of cylinders and steam con-
nections in two designs of compound locomotives according
to the von Borries system. In both figures h is the h. p.
cylinder, / is the 1. p. cylinder, A is the steam pipe from the
boiler to the h. p. cylinder, C is the receiver connecting the
two cylinders, V is the starting and intercepting valve, B is
the auxiliary steam pipe from the boiler to the starting
valve, and D is the exhaust pipe from the 1. p. cylinder.
The essential feature of the von Borries system is the
combined intercepting and starting valve, an early form of
which is illustrated by Fig. 55. In this figure a is the
receiver pipe which leads from the h. p. cylinder and b is
the passage to the 1. p. cylinder. The valve is shown in the
position which it occupies ordinarily, or when the locomo-
tive is working as a compound engine, the direction of the
flow of the steam being as indicated by the arrows. Con-
nected to the back of the intercepting valve v are two small
plungers c c which together form the starting valve. Sup-
148
COMPOUND LOCOMOTIVES.
FIG. 53
FIG. 54.
Arrangement of Cylinders and Intercepting Valve with von Borries
Automatic Starting Gear.
TWO-CYLINDER RECEIVER COMPOUNDS.
49
posing the valves to be in the positions shown in Fig. 55
and the engine about to start, when the throttle is opened
steam will be admitted to the h. p. cylinder by the usual
pipe, and also to the auxiliary steam pipe d, and by the
passage shown to the back of the plungers. The pressure
on the ends of the plungers is sufficient to move the inter-
cepting valve v to the left in the figure until it seats at e.
By the same movement two small ports h h are uncovered,
through which steam from the boiler is admitted to the
passage b and thence direct to the 1. p. steam chest, while,
as the intercepting valve is closed, this pressure does not
act against the h. p. piston.
FIG. 55.
von Borries Intercepting Valve, Early Form.
As the engine starts and the exhaust from the h. p.
cylinder takes place, the pressure in the receiver rises until
it is sufficient to overcome the pressure on the 1. p. side of
the intercepting valve, when this valve is moved back to
the position shown in the figure, while at the same time the
two small steam ports are closed by the plungers, and the
engine begins to work as a compound. It is said that in
practice the pressure of the steam from the boiler which is
admitted to the 1. p. cylinder is reduced by wire-drawing,
due to the small steam pipe and ports, to about one-half the
boiler pressure, and as the ratio of the cylinders is about
150
COMPOUND LOCOMOTIVES.
2, the total pressure on the two pistons in starting is
nearly equal. To prevent excessive pressure in the 1. p.
cylinder and receiver a safety valve is placed on the latter.
The pressure in the receiver when running is sufficient
to overcome the boiler pressure acting on the ends of the
two small plungers, together with the atmospheric pressure
on the stem of the large valve v, and therefore the valves
are maintained in the position shown in Fig. 55 as long as
the engine is running under steam.
FIG. 56. FIG. 57.
von Borries Intercepting Valve as Used on Jura, Berne-Lucerne Ry.
91. The von Borries System, as used on the Jura,
Berne-Lucerne Railway. — To facilitate starting, the engine
is fitted with a von Borries automatic starting valve, the
construction of which is shown by the detail views, Figs.
56 and 57, annexed. This apparatus is placed at the
TWO-CYLINDER RECEIVER COMPOUNDS. 151
junction of the intermediate receiver or connecting pipe
with the 1. p., the steam leaving this intermediate receiver
at R and passing off to the 1. p. cylinder at C. If the engine
stops with the h. p. piston on a dead point, so that the
engine cannot start in the ordinary way and no steam can
be exhausted to the 1. p. cylinder, the live steam passes
from the h. p. valve chest through the pipe / and acts upon
the lower end of the spindle K, the pressure thus exerted
raising the valve 5 and closing it on the seat Si. When the
spindle K is thus lifted it uncovers the small openings e e,
and live steam can then pass to the 1. p. cylinder, thus
starting the engine. As soon as the engine gets to work
the exhaust from the h. p. cylinder, of course, raises the
pressure in the intermediate receiver, and this pressure
acting on the valve 5 overpowers the pressure of the live
steam on the lower end of the spindle K and the receiver
pressure on the valve S, and forces the valve off its seat,
thus allowing the exhaust steam from the h. p. cylinder to
pass to the 1. p., the engine then continuing to work com-
pound. To insure the valve S being forced down into the
position in which it is shown in Figs. 56 and 57, there is
provided a small piston p working in a cylinder a} the
upper end of which is in free communication with the
receiver. The area of this piston is such that the pressure
of the receiver steam on it is sufficient to over-power the
pressure of the live steam on the lower end of the spindle K.
92. A Modification of the von Borries System. — A
modification of the von Borries intercepting valve is shown
in Fig. 58. This valve is placed in the side of the
smoke box, and is connected at A by a small pipe to the
steam pipe from the boiler. When the throttle is opened
steam enters the passage C by way of the pipe, and press-
ing against the shoulder of the steel spindle D, pushes it
into the position shown in Fig. 58, and thus closes the
valve. The steam then passes around the spindle, out
152
COMPOUND LOCOMOTIVES.
through the y2 inch opening and into the chamber B, which
communicates with the receiver. Then it has free access
to the steam chest of the 1. p. cylinder. It also acts against
the piston E through the passage F, but the greater area of
the main valve keeps it closed.
FIG. 58.
Recent Modification of von Borries Intercepting Valve.
When the h. p. cylinder exhausts into the chamber A,
the pressure, which has heretofore been equal to that of the
atmosphere, rises on that side of the valve and thus balances
the receiver pressure. Then, as the area of E is greater
than that of the shoulder on D the valve is moved to the
right, and the communication between the h. p. exhaust
and the receiver is again established. In this position the
larger portion of the stem D closes the ^ inch openings and
the engine works as a compound. It may be added that the
openings are so graded that the steam is wire-drawn down
to the proper pressure for admission to the 1. p. cylinder.
TWO-CYLINDER RECEIVER COMPOUNDS,
153
93. Recent Changes in the von Borries System.—
After several years careful watching of the locomotives
fitted with automatic intercepting valves, Mr. von Borries
has reached the conclusion that it is better to give to the
engineer a control over the intercepting valve, and to pro-
vide a separate exhaust for the h. p. cylinder at starting.
With this change in view a new arrangement of starting
gear has been devised. It is described, with other non-
automatic starting gears, in Chapter XVII, 116.
94. The Worsdell System, — This system is strictly
automatic, which means that the change from the use of
boiler steam in the 1. p. cylinder to full compound action is
FIG. 59.
Arrangement of Cylinders, Worsdell Two-Cylinder Type.
controlled automatically beyond the will of the engineer,
and takes place whenever the pressure in the receiver,
resulting from the exhaust of the h. p. cylinder, rises to a
154
COMPOUND LOCOMOTIVES.
point .where it is sufficient to actuate the automatic
mechanism. In Fig. 59 h and / represent the h. p. and
1. p. cylinders, respectively, A is the h. p. steam pipe, C is
the receiver, D is the 1. p. exhaust pipe, B is the steam
FIG. 61.
Early Form of Worsdell Intercepting Valve.
•
supply to the starting valve v} and V is the intercepting
valve.
The Worsdell starting and intercepting valves are illus-
trated by Figs. 60 and 61. The intercepting valve is a flap
valve, and is shown in Fig. 60 in the position which it
occupies when the engine is working as a compound, being
swung to one side, and thus leaving a straight, clear passage
by it. The spindle on which the valve turns passes out
through the side of the smoke box, and carries an arm,
, TWO-CYLINDER RECEIVER COMPOUNDS. 155
which is connected to the small piston shown at a, Fig. 61,
in a manner which is clearly indicated in the figures. The
starting valve casing is connected to the main steam pipe
by a small pipe, which is shown in Fig. 61, and also in Fig.
59. The piston a, which operates the intercepting valve by
means of the connection previously referred to, works in a
cylinder which is an extension of the starting valve casing.
A small port, which is covered by a spring-loaded valve,
connects this cylinder with the pipe 6, and thus to the
intercepting valve chamber. The starting valve is operated
by a lever, and is a double valve,' a slight movement of the
lever opening the smaller valve, and further motion opening
the larger valve, which is then partially balanced.
The operation of these valves in starting is as follows:
The starting valve being opened by the engineer, steam, at
boiler pressure, acts upon the small piston a, and moves it
forward or to the left in the Fig. 61. By the same movement
the intercepting valve is swung up and closed, and the port
connecting with the pipe b is uncovered, thus admitting
steam from the boiler to the intercepting valve chamber
below the valve, and thence to the 1. p. steam chest. As
the exhaust takes place from the h. p. cylinder, the pressure
in the receiver, above the intercepting valve, rises until it is
sufficient to open that valve, when, by its movement, the
small piston a is returned to the position shown in Fig. 6.1,
and the steam supply is thus shut off.
95. A Modification of the Worsdell System. — This
is shown in Figs. 62 and 63. It is automatic in action, as it
allows live steam to be admitted to the 1. p. cylinder at start-
ing and automatically cuts off this supply, thus converting
the engine into a compound when the receiver pressure
has been raised to the proper point by the h. p. exhaust.
When the engine driver opens the throttle valve,- steam
is admitted through the holes A A over the stems of the
plungers C C. These plungers are then forced to the right,
156
COMPOUND LOCOMOTIVES.
pushing the main valve against its seat and opening the
port holes B B that connect with the chamber E, as shown
in the cross section, Fig. 63, which leads directly to the
steam-chest of the 1. p. cylinder. Thus the live steam is
FIG. 62.
Recent Modification of Worsdell Intercepting Valve.
also admitted below the relief valve //, so that should the
pressure in the 1. p. steam-chest rise above that desired, this
valve will open and allow the excess of steam to escape into
the smoke-box. The small flap valve G which closes the
passage F from the safety valve is used to prevent an
accumulation of cinders collecting about the safety valve as
TWO-CYLINDER RECEIVER COMPOUNDS.
157
a result of long disuse. A drop pipe K is also provided to
carry off the water condensation and leakage from the
annular space 0.
After the h. p. cylinder has exhausted into the chamber
D, the pressure in that chamber rises so that finally the
FIG. 63.
Modification of Worsdell Intercepting Valve.
pressure on the under side of the valve overcomes that on
the stems C C, and the valve opens, re-establishing com-
munication between the exhaust D of the h. p. cylinder and
the receiver E of the 1. p. At the same time the stems C C
close the ports B B and the engine proceeds with its work
as a compound. The plug shown screwed into the valve
is merely used to plug up the core hole made in casting the
valve.
96. The Schenectady Locomotive Works (Pitkin)
System. — This system is strictly automatic, inasmuch as the
change from the use of steam directly from the boiler into
the 1. p. cylinder is controlled automatically and is beyond
the will of the engineer. The change from the use of steam
directly in the 1. p. cylinder to full automatic action occurs
whenever the exhaust pressure from the h. p. cylinder accum-
ulates in the receiver to a point where it will actuate the auto-
158
COMPOUND LOCOMOTIVES.
matic mechanism. The general arrangement of the cylinders
and steam connections of this locomotive is show by Fig.
64. The distinctive feature of the engine is the intercept-
ing valve, which is shown by Fig. 65, which is a plan of the
bushing which incloses the valve, and by Fig. 66 which is a
vertical section through the valve, bushing and saddle.
The valve is shown in the position which it occupies in
starting; that is, before compound working begins. In this
FIG. 64.
Arrangement of Cylinders and Receiver, Schenectady (Pitkin) Type.
position the ports c and d are closed oy the intercepting
valve and the connection between the 1. p. steam chest and
the receiver is thus cut off. The small port a, Fig. 65, is
connected by a pipe and a pressure-reducing valve to the
h. p. steam pipe. By this means steam at reduced pressure
is admitted to the space b and thence, as indicated by the
arrow, to the 1. p. steam chest. As the parts of the valve
on either side of b are of different diameters, the pressure
in this space tends to hold the valve in the position shown
in Fig. 66. When the locomotive starts, the h. p. cylinder
exhausts into the closed receiver, and the back pressure
thus created acts upon the forward end of the intercepting
TWO-CYLINDER RECEIVER COMPOUNDS.
159
valve by means of the passage shown at e. The pressure in
the receiver rapidly increases until the total pressure on the
forward end of the valve is sufficient to overcome the total
effective pressure at b, when the valve is forced to the back
end of. its stroke, the direct steam supply to the 1. p. cyl-
l6o COMPOUND LOCOMOTIVES.
inder is cut off, and compound working begins. To prevent
the valve moving too rapidly a dash-pot, in the form of an
oil cylinder, h, is added. The valve stem is continued
through this oil cylinder, and is connected by levers to
an index in the cab which indicates the position of the
valve.
97. A Modification of the Schenectady Locomotive
Works (Pitkin) System. — This system is illustrated by
Figs. 67 to 71 inclusive. There are two pistons A A at
one end of the single stem B, which moves to and fro in a
cylindrical chamber having three openings. Two of these
openings, C C, lead to the receiver and to the 1. p. steam
chest, and it is the office of the pistons A A to open and
close these large openings and prevent the steam in the 1.
p. steam chest from entering the receiver when it is not
wanted there. The other opening, D, in this cylinder,
connects the intercepting valve cylinder with the 1. p. steam
chest. There are holes through the pistons A A which
admit the 1. p. steam chest pressure to the right hand end
and thus balance these pistons and prevent movement by
either receiver pressure or by the pressure in the 1. p.
.steam chest.
The remaining portion of the mechanism is the appa-
ratus for driving and connecting the intercepting valve. It
is constructed as follows :
On the end of the stem B, which passes through a stuff-
ing box in the end of the intercepting valve chamber, there
is a piston E, which moves in a small cylinder having ports
F and G, one at each end. These ports lead to a valve seat
on which is a plain D valve not unlike the ordinary locomo-
tive* slide valve. This slide valve is moved to and fro by
means of a double piston with a stem between, shown at
/and K. These pistons are of different diameters, A' being
larger than/; and as they move to and fro. they carry with
TWO-CYLINDER RECEIVER COMPOUNDS. l6l
FIG. 67.
Modification of the Schenectady Automatic Intercepting Valve.
Complete Details.
FIG. 68.
Modification of the Schenectady Automatic Intercepting Valve.
Plan Intercepting Valve Open.
l62 COMPOUND LOCOMOTIVES.
them the slide valve. The office of this portion of the
mechanism is to move the intercepting valve A A to and
fro as desired.
The third part of the device consists of a balance poppet
valve L, which is placed in the path of steam coming direct
from the boiler to the 1. p. cylinder to assist in starting.
This valve has an extended spindle, M, on the lower side,
and is lifted by means of a bell crank, N, which is driven by
means of a trunnion on the intercepting valve stem B. As
the stem B passes to the right, the valve L is lifted, and as
FIG. 69. FIG. 70.
Details of Modification of Schenectady Automatic Intercepting Valve.
it passes to the left the valve L is allowed to fall. Fig. 69
is a detail of the pipe connections and passages leading to
the pistons JK, the office of which will be described in what
follows. Fig. 70 is a section through the slide valve H
showing that it has a cylindrical seat. The operation of this
valve is a follows:
The engineer opens the throttle, as usual. Boiler steam
passes through the pipe P, which is tapped into the h. p.
steam pipe to the apparatus which actuates the intercepting
valve, as shown in Figs. 68 and 69. It enters through Q
and forces the small regulating valve R to the right and
then passes down through the left port 5 between the pistons
J and K. K being larger than /, it has a greater total
pressure ; hence, the pistons move to the right and carry the
slide valve with them. This opens the port F and allows
the steam to pass on the left side of the piston E, and forces
it, together with the intercepting valve A A, to the right
until it is in the position shown in Fig. 71, with the C C
TWO-CYLINDER RECEIVER COMPOUNDS.
163
passages closed. The position of the pistons / K and the
slide valve //at this time are shown in Fig, 71.
During the foregoing operation, as the intercepting valve
stem B moves to the right it carries with it the bell crank N
to the position shown in Fig. 71, thus lifting the balance
poppet valve L and admitting steam, as shown by the arrows,
Fig. 71, into the intercepting valve cylinder, from whence
FIG. 71.
Modification of Schenectady Automatic Intercepting Valve.
Intercepting Valve Shut.
it passes out through the opening D into the 1. p. cylinder
steam chest, and in this way steam is admitted direct from
the boiler to the 1. p. steam chest always just before the
engine starts.
As soon as the engine has started and there is an exhaust
into the receiver from the h. p. cylinder, steam passes from
the receiver through the pipe T, shown in Fig. 69, to the
passages U leading to. the piston K. This pressure acts on
the right hand side of the regulating valve R, moves it to the
left thus opening the right port 5 and also acting on the
larger piston K, moves the slide valve H and opens the
steam passage G, Fig. 68, and the exhaust passage V, and
admits steam to the right hand side of the piston E, and
drives it to the left, and with it the intercepting valves A
A, thus opening the passages C C and the receiver to the 1.
p. steam chest. At the same time the bell crank N is
164
COMPOUND LOCOMOTIVES.
moved to the left and the valve L is al )\ved to drop into
the position shown in Fig. 68, thus cutting off the connec-
tion between the boiler and the 1. p. steam chest. After this
the engine works in the well-known way of the two-cylinder
compound ; that is, by taking steam into the h. p. cylinder,
FIG.
Location of Schenectady Modified Intercepting Valve
discharging it into the receiver, taking it out of the receiver
into the 1. p. cylinder and discharging it into the atmos-
phere. Fig. 69 shows the external appearance of the
mechanism.
One of the Schenectady two-cylinder compounds on the
Southern Pacific has been fitted with an independent exhaust
for the h. p. cylinder. The arrangement is simply a piston
TWO-CYLINDER RECEIVER COMPOUNDS. 165
valve attached to a receiver pipe that is actuated from the
cab. At starting, or whenever it is desirable to run the
engine with a separate exhaust for the h. p. cylinder, the
engineer moves a handle in the cab which opens the piston
valve to the atmosphere.
98. The Dean System.— This system is strictly auto-
matic, inasmuch as the change from the use of steam directly
from the boiler into the 1. p. cylinder is controlled automa-
tically, and is beyond the will of the engineer. The change
from the use of steam directly in the 1. p. cylinder to full
automatic action occnrs whenever the exhaust pressure from
the h. p. cylinder accumulates in the receiver to a point
where it will actuate the automatic mechanism. In the
first design the intercepting valve operated almost exactly
as that now used, but it was located in the smoke box.
The converting valve was placed on the h. p. steam chest
cover as shown in Fig. 74. In the present design the
intercepting valve and converting valve are joined together
and are located on the h. p. steam chest. The receivers
are made of cast iron with ribs, as shown in Fig. 72.
99. A Modification of the Dean System. — Recently
this gear has been modified, and the intercepting and con-
verting valves are bolted to the top of the h. p. steam chest
cover, and have connected to them a ^ -inch steam pipe for
conveying live steam to the intercepting valve for lifting it
and securing it in its highest position. See Fig. 72. This
pressure is from the boiler and is exerted at all times
whether the engine is running or not.
The h. p. main slide valve is open at the top, and the
exhaust steam from the h. p. cylinder passes upward through
it and a port in the balance plate into the steam chest cover,
instead of down through a port in the cylinder as usual ; by a
passage shown in Figs. 72 and 75 it passes to the receiver.
The starting valves consist of a converting valve and an
intercepting valve. The former seats over a hole in the
1 66
COMPOUND LOCOMOTIVES.
live steam part of the steam chest cover, see Figs. 73 and
74. When the throttle valve opens the converting valve is
lifted and steam passes through into the intercepting valve,
FIG. 72.
Dean's Automatic Intercepting Valve — Cross Section Through Cylinders,
• and Plan of Steam Chest.
see Fig. 73, which is forced down slowly on account of the
steam being wire-drawn through small holes in the inter-
cepting valve, and because of the boiler steam that holds
up the intercepting valve, see Fig. 75. When the inter-
TWO-CYLINDER RECEIVER COMPOUNDS.
I67
cepting valve is nearly on its seat radial holes in the valve
allow live steam from the converting valve to pass through
into the receiver and into the 1. p. cylinder. Thus the 1.
FIG. 73-
Dean's Automatic Intercepting Valve — Longitudinal Section
Through High-Pressure Cylinder.
p. cylinder receives steam for starting. When the h. p.
cylinder exhausts, the pressure in the receiver acts through
a passage, shown in Fig. 74, on the top of the converting
valve, moves it downward, and shuts off the supply of live
steam. At the same time the grooved stem at the bottom
1 68
COMPOUND LOCOMOTIVES.
of the converting valve allows the steam that is holding
the intercepting valve down to escape into the atmosphere,
and thus enables the boiler steam in .the annular space
around the intercepting valve to lift that valve. The
engine then acts as a compound engine.
FIG. 74.
Dean's Converting Valve — Cross Section Through High-
Pressure Cylinder, before Modification.
In order to prevent the steam, coming from the con-
verting valve at starting, from getting under the intercept-
ing valve, the disc of that valve enters a lip around its seat
before the starting steam is allowed to enter the receiver.
Both valves are cushioned to prevent slamming in either
direction, and provision is made for oiling.
TWO-CYLINDER RECEIVER COMPOUNDS. 169
FIG. 75.
Dean's Modified Automatic Intercepting Valve — Cross Section Through
High-Pressure Cylinder.
100. The Brooks Locomotive Works (Player)
System. — This system is strictly automatic, inasmuch as
the change from the use of steam directly from the boiler
into the 1. p. cylinder is controlled automatically, and is
beyond the will of the engineer. The change from the use
of steam directly in the 1. p. cylinder to full automatic
action takes place whenever the exhaust pressure from the
h. p. cylinder accumulates in the receiver to a point where
it will actuate the automatic mechanism. It is shown in
Figs. 76, 77, 78, 78a.
I7O COMPOUND LOCOMOTIVES.
The exhaust from the h. p. cylinder passes into the
receiver as usual. Its passage to the 1. p. cylinder is gov-
erned by an intercepting valve, shown in detail in Figs. 78
and 78a. A pipe leads from the main steam pipe to the end
of the intercepting valve, as shown in Figs. 76 and 77, and the
steam entering there when the throttle is opened forces the
duplex piston forward and closes the intercepting valve, as
shown in Fig. 78. The intercepting valve is formed of an
annular piston which works on the outside of the duplex
piston, as shown. As the duplex piston moves forward,
steam is admitted through the interior of that piston, see
Fig. 78a, and into the receiver, and passes thence to the 1. p.
cylinder. In this way the pressure in the receiver increases
and finally returns the duplex piston to its seat, see Fig. 78,
and stops the admission of boiler steam to the 1. p. cylinder.
This last movement is caused by the pressure in the receiver
acting on the larger piston of the duplex piston, against the
steam pipe pressure acting on the smaller piston of the
duplex piston. In this way the duplex piston becomes a
reducing valve, which reduces pressure of the steam between
the steam pipe and the 1. p. cylinder according to the area
of the two pistons of the duplex piston. When the pressure
in the receiver has been raised by the exhaust from the h. p.
cylinder, the intercepting valve is forced open and the
admission of steam from the steam pipe is shut off by the
valve-end of the duplex piston which is forced back to its
seat. There is an outlet to the atmosphere which prevents
the pressure accumulating on the back side of the annular
piston of the intercepting valve, see Figs. 78 and 78a.
In order to move or stop the engine quickly when
desired, as for round house work, two valves are attached
to the receiver, one on the h. p. side and the other on the 1.
p. side, which can be opened by a lever in the cab. The
opening of the valve on the h. p. side permits the engine to
be used like a single expansion engine in a very limited way,
TWO-CYLINDER RECEIVER COMPOUNDS.
171
as the exhaust from the h. p. is allowed to pass to the
atmosphere through this comparatively small auxiliary valve.
The valve on the 1. p. side of the receiver is kept shut while
the engine is being moved, but when it is desired to stop
quickly, the opening of this valve permits the escape of all
the steam in the 1. p. steam-chest and in the 1. p. side of the
receiver. In this way the locomotive is stopped quicker
than it would be if the cylinders had been used compound.
101. Rogers Locomotive Works System. — This
system is strictly automatic, inasmuch as the change
172
COMPOUND LOCOMOTIVES.
from the use of steam directly from the boiler into the 1. p,
cylinder is controlled automatically and is beyond the will
FIG. 77.
Brooks (Player) Automatic Intercepting Valve — Longitudinal Section
Through Low-Pressure Cylinder.
of the engineer. The change from the use of steam directly
from the 1. p. cylinder to full automatic action takes place
TWO-CYLINDER RECEIVER COMPOUNDS. 173
whenever the exhaust pressure from the h. p. cylinder accu-
FIG. 78.
Brooks (Player) Automatic Intercepting Valve — Reducing Valve Closed.
FIG. 78a.
Detail of Brooks Automatic Intercepting Valve — Reducing Valve Open.
mulates in the receiver to a point where it will actuate the
automatic mechanism. It is shown in Figs. 79, 80 and 81.
174
COMPOUND LOCOMOTIVES.
The intercepting and reducing valves are shown in detail
in Fig. 79. The reducing valve consists of a valve B and
piston A, mounted on a stem F, in an iron chamber/, the
space between the valve and piston being filled by steam
supplied from the live steam pipe through a 2^4 inch con-
FIG. 79.
Details of Rogers Automatic Reducing and Intercepting Valves.
Intercepting Valve Open.
nection. The net area of the upper side of the valve B is
8.30 square inches, while that of the under side of piston A is
3. 96 square inches. The chamber <2» above piston A, opens
to the atmosphere through port X, so that any leakage past
the piston will not interfere with the free action of the
valve. Neglecting friction, the valve will open when the
TWO-CYLINDER RECEIVER COMPOUNDS.
175
pressure beneath the valve drops below 52 per cent, of the
live steam pressure in the valve chamber /, thus admitting
live steam to the passage, which leads to the intercepting
valve.
The opening of this reducing valve is controlled by
the position of the reverse lever, the arrangement being
such that the reducing valve can open only when the reverse
lever is in the extreme backward or forward gear. Refer-
FIG. 80.
Rogers Automatic Intercepting Valve — Details of Cab Connections.
ring to Fig. 79, it will be seen that the upper end of the stem
F of the reducing valve is slotted to receive the short arm
at G. This arm is mounted on a short shaft, to which is
keyed a longer arm //, the end of which drops nearly to the
centre of the smoke box. Attached to this arm will be seen
a rod leading back to the mechanism, shown in Fig. So.
This device is actuated by an independent reach rod from
the reverse lever, Fig. 81. The shape of the curved slot on
this mechanism is such that when in mid-gear the arm G
lifts on the valve stem F of the reducing valve with such
force as to prevent its opening, but when in extreme for-
ward or backward gear, the tension of this rod is released
by the friction wheel A' , Fig. 80, passing into the incline of
the curved slot at either end, then the arm G drops to such
a position as to allow the valve to open or remain closed,
according to the pressures in and befow the reducing valve.
1 76
COMPOUND LOCOMOTIVES.
The steam, after passing through the reducing valve,
flows through the 2 inch pipe L to the intercepting valve.
The valve proper consists of a plain flap valve 0 which
closes diagonally across the receiver pipe in such a way as
to prevent the steam admitted to the 1. p. cylinder from
backing up against the h. p. piston and reducing its
power. This flap valve is con-
nected to a hollow piston T by
means of the link U. Around
the wall of the cylinder in
which the hollow piston T is
loosely fitted is an annular
steam chamber E E connected
with the pipe L. Through this
cylinder wall there are eight
y% inch holes at / / and through
the wall of the hollow piston T\
there are also eight holes,
inches diameter at K K, which,
when the piston T moves out-
ward, correspond with holes /
/, and steam from E will then
pass through into T. T also
has eight T9^ holes M M at its
inner end, and as these holes,
when the intercepting valve is FIG. 81.
Closed, are outside of the end Details of Cab Connections —
of the cylinder, steam will pass Rogers IntercePtins Valve-
out through them into the space N below the intercepting
valve and on to the 1. p. steam chest. The head IV, on
the back end of plunger cylinder, Fig. 79, is chambered
out as shown at 5 5. In the back end of the hollow
piston T is a solid plunger P. This plunger extends
through a hole Y in the inner wall of the head into the
chamber 5 5 fitting loo'sely in Y. From the annular space
TWO-CYLINDER RECEIVER COMPOUNDS. 177
E E through the inner wall of the head at ZZ are two holes
(one top and one bottom) -^ inch diameter into the cham-
ber vS *S for the passage of steam to operate on the plunger
P in closing the intercepting valve 0. The dimensions
of these parts are as follows :
Diameter of the hollow piston T outside, 3 inches.
11 " " " inside, 2^ inches.
Stroke to close 0, about 5 inches.
Diameter of plunger P, i ^ inches.
When the parts are in the position shown in Fig. 79,
steam is admitted through the pipe L to the annular cham-
ber E, but as the holes / / do not correspond with the
holes in the wall of 7", steam can only pass through the
two holes Z Z into 5 S, where operating on the end of the
plunger P it causes the piston T to move outward closing
the intercepting valve, and at the same time bringing the
holes K Km correspondence with the holes //and allow-
ing steam from the pipe L to pass through the hollow
piston T out at the holes M M at its end into N and on to
the 1. p. steam chest. The object of wire-drawing the steam
through the small holes Zzfand to have it operate on the
comparatively small area of P (about 2.4 square inches)
in closing the intercepting valve, is to cause as slow a
movement of the piston T and as light a shock in seating
the valve as practicable. There are no steam-tight joints or
packing in any of the moving parts for closing the intercept-
ing valve. Whenever the valve B of the reducing arrangement
is closed, no live steam can get to the 1. p. cylinder. To
permit the piston T to go back. to the position shown, when-
ever the pressure becomes equal on both sides of the inter-
cepting valve, without resistance, leakage holes are provided
at C and D and by these holes and holes Z Z steam can
pass through from N to T to 5 and to L. These holes
also prevent slight differences in pressure between TV and L,
from causing unnecessary movement of the piston T.
178 COMPOUND LOCOMOTIVES,
The locomotives that have been built with this starting
gear are given in Table C C, Appendix R.
102. The Baldwin Locomotive Works System. — Figs.
82, 83, and 84, show the automatic intercepting valve and
starting apparatus devised by the Baldwin Locomotive
Works for a two-cylinder receiver compound for the ele-
FIG. 82.
Baldwin Automatic Intercepting Valve — Cross Section Through Cylinders.
vated road of the Chicago & South Side Rapid Transit
Railroad Company, Chicago. Fig. 82 shows how the steam
passes from the boiler to the h. p. cylinder through the
steam passage in that cylinder. Opening out of this pas-
sage is a starting valve shown in detail in Fig. 84, which is,
in fact, a reducing valve, which does not permit the pressure
in the receiver to exceed 100 pounds. The boiler pressure
is 1 80 pounds. Whenever there is 180 pounds of steam
TWO-CYLINDER RECEIVER COMPOUNDS.
179
pressure in the h. p. steam chest and the pressure in the
receiver is less than 100 pounds, the reducing valve opens
and steam is admitted through a pipe into the receiver.
The reducing valve is a single seated valve moved by an
annular piston, all of which is cast in one piece, as shown
FIG. 83.
Baldwin Automatic Intercepting Valve — Side Elevation.
in Fig. 84. As the piston rises and falls under the varia-
tions in steam pressure, the reducing valve is opened and
shut.
In the smoke box is an automatic intercepting valve
which is opened like other automatic intercepting valves by
the exhaust from the h. p. cylinder. This intercepting
valve is a simple piston moving vertically in a cylinder
formed by the inner casing of a thimble fitted into the
i8o
COMPOUND LOCOMOTIVES.
receiver. Above the piston there is atmospheric pressure,
and below the piston the pressure in the receiver. Hence,
the intercepting valve is always open when there is pressure
enough in the receiver to lift the valve which is in the
form of a plunger. The valve is rather heavy and drops
FIG. 84.
Baldwin Automatic Intercepting Valve — Detail of Reducing Valve.
whenever the pressure in the receiver is reduced by the
closing of the throttle of the engine. In practical operation
the weight and area of this intercepting valve is so arranged
that it will keep shut until the engine has made one revolu-
tion or less, after which the pressure in the exhaust pipe
of the h. p. cylinder has accumulated to an amount that
will lift the valve and permit the engine to work compound.
CHAPTER XVI.
DESCRIPTION OF TWO - CYLINDER RECEIVER COMPOUNDS
WITH AUTOMATIC STARTING GEAR AND WITHOUT SEP-
ARATE EXHAUST FOR HIGH -PRESSURE CYLINDER AT
STARTING AND WITHOUT INTERCEPTING VALVE. THE
LINDNER SYSTEM; THE COOKE LOCOMOTIVE WORKS
SYSTEM; THE GOLSDORF (AUSTRIAN) SYSTEM.
103. The Lindner System. — This system is not strictly
automatic, and perhaps has some advantages for that reason ;
however, when the engine is operated in the usual way by
the locomotive engineer, the system is practically auto-
matic. It is only in the extreme forward and back position
of the reverse lever that steam is admitted directly from
the boiler to the 1. p. cylinder, and as the engines are gen-
erally run only for the first two or three revolutions with
the reverse lever in the extreme notches, it is evident that
under ordinary conditions the engineer would cut out the
admission of steam directly from the boiler to the 1. p. cylin-
der by hooking up the reverse lever. If it was desired to
use boiler steam in the 1. p. cylinder for a longer period,
it is only necessary to allow the reverse lever to remain
in the extreme notch. The admission valve is shown by
Fig. 85. C is the receiver, E is a small pipe connecting
the receiver and the main steam pipe, and /is the starting
valve, which has two ports, H and /, formed in it at right
angles. The lever K by which the valve is operated is con-
nected to the reach rod, and the proportions are such that
K turns through ninety degrees, as indicated in the figure
when the reverse lever is moved from one extreme position
to the other. The effect is that steam from the boiler is
admitted to the receiver when the valve motion is in either
181
182
COMPOUND LOCOMOTIVES.
the extreme forward gear or the extreme backward gear,
and the cock is closed for intermediate positions.
Another feature of the Lindner system is the introduction
of two small ports, see Fig. 87^, of small area in the h. p. slide
FIG. 85.
Lindner Starting Valve- — General Form.
valve, which are so located that when the valve covers the
steam port, at one end of the h. p. cylinder, as after cut-off
takes place, that end of the cylinder is connected by means
of one of these small ports with the exhaust side of the valve
and thus with the receiver. The effect is to admit steam at
receiver pressure to the end of the h. p. cylinder, which
is covered by the slide valve, and as the other end is then
open to the exhaust and hence to the receiver pressure, the
pressure on the two sides of the h. p. piston is partially
equalized. In other words, the effective back pressure on
the h. p, piston is more or less reduced, so that it offers
less resistance in starting. This device is useful in starting
only for such piston positions as lie between full cut-off
and the end of the stroke.
The effect of the Lindner starting gear will depend
somewhat upon whether or not a relief valve is provided
TWO-CYLINDER RECEIVER COMPOUNDS. 183
to limit the maximum pressure in the receiver. If
this receiver pressure is equal to ^ of the boiler pressure,
with a cylinder ratio of 2, the effect of the starting valve
is to enable the engine to start with very nearly the same
distribution of pressures on the pistons as would be found
when it is working as a compound in full gear. The result-
ing rotative efforts will then be represented by a curve such
as the full line curve in Fig. 30, the ordinates or actual
pressures, however, being less than those for the single
expansion engine in about the proportion of 113 to 150,
with boiler pressures of 170 and 150 pounds.
If the receiver pressure is allowed to become higher
than y^ the boiler pressure, the back pressure on the h. p.
piston is increased proportionately, and the result is that
the power of the h. p. cylinder is reduced, while that of
the 1. p. cylinder is increased. The advisability of using
the higher pressure depends upon the positions of the cranks
at starting. If the 1. p. crank is at a dead point, the maxi-
mum effort will be obtained by not admitting any steam to
the receiver at the instant of starting, but before the engine
has made ^ of a revolution some pressure in the receiver
will be necessary to enable the 1. p. piston to act. The
other extreme is when the h. p. crank is at a dead point in
starting. When this is the case, the 1. p. crank being then
on the half centre, full boiler pressure cculd be advan-
tageously used in the 1. p. cylinder, with the result of
obtaining a rotative effort about 4 times as great as in a
single expansion engine starting with the same crank posi-
tions. But similarly to the first case, the receiver pressure
should be reduced almost as soon as the engine begins to
move, or else the h. p. piston will be practically thrown out
of action, and the engine might be stalled after making ^
of a revolution.
It appears, then, that with this starting valve and a
properly loaded relief valve on the receiver the starting is
184 COMPOUND LOCOMOTIVES.
very simple ; but the power is less than that of the single
expansion engine having cylinders of the same size as
the h. p. cylinder of the compound, the boiler pressures
being 170 and 150 pounds, respectively. With no safety
valve, the utility of the device depe'nds upon the position of
the crank and the judgment of the engineman, 66.
104. A Modification of the Lindner System. — The
latest form of the Lindner system is a modification of the
first. » It consists of running the pipe which formerly led
from the four-way cock to the receiver, into the side of the
steam chest. At this point is formed a small valve seat
over which rides a flat valve without ports, which is attached
rigidly to the valve yoke. This valve is made of such
length that when steam is not wanted in the 1. p. cylinder
for useful effect in starting, it is shut out by the valve, and
is not permitted to enter the receiver and back up against
the h. p. piston. By it steam can be shut out of the receiver
when it is advantageous to do so. It operates in the same
general way as an intercepting valve, but has the advantage
of being capable of regulation to a greater degree. This
is the device used on the present Lindner engines and on
the Pennsylvania and C., B. and Q. compounds illustrated
in 106 and 107.
A further modification of the Lindner system is some-
times made for locomotives having two h. p. cylinders and
one receiver common to both, and for express engines hav-
ing large driving wheels and comparatively small cylinder
power. This modification consists in admitting steam, at
starting, to the pipe leading to the 1. p. steam chest, through
a small auxiliary port in the throttle valve, in such a way
that steam is admitted to the h. p. steam chest through the
throttle valve in the regular way, before the steam is admit-
ted from the boiler through the small auxiliary port in the
throttle valve, to the pipe leading to the 1. p. chest. In
this way full pressure is admitted to the h. p. steam
TWO-CYLINDER RECEIVER COMPOUNDS. 185
chest before steam is admitted to the auxiliary pipe leading
to the 1. p. steam chest. The object of this is to give full
pressure to the h. p. piston when that piston has to start
the engine before any steam is admitted to the 1. p. steam
chest or receiver. This arrangement is easily adapted for
throttles in the form of a slide valve, but is difficult to
apply to engines having a double poppet valve.
105. The Lindner System as Used on the Saxon
State Railroad; The Meyer -Lindner Duplex Com-
pound.— A four-cylinder compound of the Duplex type
has been built for the Saxon State Railroad by the Chem-
nitz Engine Works with the Lindner starting gear. The
engine is known as the Meyer-Lindner Duplex Compound.
It is in reality a double two-cylinder compound with re-
ceiver, there being two h. p. cylinders on one motor truck,
which exhaust into a common receiver which feeds two 1. p.
cylinders on the other motor truck. The ratio of the
cylinders is 2.35. It is claimed for duplex engines of this
type, as it is for the Mallet duplex engines, that if the 1. p.
driving wheels slip they will be stopped at once, because
while the slipping is going on the steam required for the
1. p. pistons will exceed the amount delivered from the h. p.
cylinders, and the turning moment on the driving wheels
of the 1. p. truck will thus be decreased. In the same way,
if any slip should occur with the h. p. truck wheels, it will
quickly be stopped, because then more steam would be
going from the h. p. cylinders than the 1. p. cylinders could
receive, and there would be a rapid increase of back pres-
sure from the receiver, with a corresponding decrease of
the power exerted on the drivers.
106. The Lindner System on the Chicago, Burlington
& Quincy Railroad. — Two compound locomotives of the
Mogul type have been built by the Chicago, Burlington &
Quincy Railroad at the Aurora shops, from designs of
Mr. William Forsyth, Mechanical Engineer of that road.
1 86
COMPOUND LOCOMOTIVES.
The first engine had the early form of the Lindner gear,
that is, without the ports in the sides of the steam chest
of the 1. p. cylinder over which the fixed valve on the
side of the valve yoke passes. This locomotive has given
excellent service since it was first built. It has now the
FIG. 86.
Lindner Starting Valve on C., B. & Q. Compound.
latest form of Lindner gear except the connection to the
throttle. Figs. 35 and 36 show the general arrangement of
cylinders, receiver and the pipe to the starting valve, and
Figs. 86, 86#, 87 and 87*2 show the valves and their applica-
tion to the engine in question. Figs. 86, S6a and 87 show
the application of the starting valve to the 1. p. steam chest
and cylinder saddle, and also the fixed valve on the valve
yoke which keeps the admission port for live steam into
the 1. p. cylinder closed, except when it is desired that steam
TWO-CYLINDER RECEIVER COMPOUNDS.
i87
should be admitted. Full control of the admission of steam
into the 1. p. cylinder is obtained in this way. Fig. S?a
FIG. 86a.
Lindner Starting Valve on C., B. £ Q. Compound — Section.
FIG. 87.
Lindner Starting Valve on C., 13. & Q. Compound — End View,
shows the h. p. steam valve in section, and indicates how
the small balancing ports used with the Lindner system are
introduced in the h. p. steam valve. Figs. 35 and 36 give the
i88
COMPOUND LOCOMOTIVES,
location of the receiver and the piping for the starting valve.
The starting valve is connected by a rod with a supple-
mentary vertical arm on the reverse shaft. This is shown
in Figs. 35 and S6a. With this arrangement the locomo-
FIG. Sya.
Main Steam Valve of Lindner Compound on C., B. & Q.
tive starts freight trains in regular service, and all ordinary
passenger trains, without difficulty. The C., B. & Q. road
adopted this arrangement on account of its simplicity.
The second engine, with, the compound system, is also built
with this device.
107. The Lindner System on the Pennsylvania Rail-
road.— A very interesting compound on the Lindner system
TWO-CYLINDER RECEIVER COMPOUNDS.
189
has been built by the Pennsylvania Railroad at the Altoona
shops from the design of Mr. Axel S. Vogt, Mechanical
Engineer. The engine was built for the heaviest class of
passenger service, and has been in service but a short time
Class-T-Compound
200 Ibs. Pressure
t8ii:___ IL_ !~7"T8- -j
FIG. 88.
Pennsylvania Compound with Lindner Starting Gear — Side
Elevation of Engine.
LJ_L
Line of Rail
FIG. 89.
Pennsylvania Compound with Lindner Starting Gear — End
Elevation of Engine.
at this writing. Some changes were required in the valve
motion and smoke box apparatus to improve the steaming
of the engine, and she has been taken from service to have
these changes made. This is undoubtedly the heaviest four
I QO COMPOUND LOCOMOTIVES.
coupled compound locomotive yet made. The general type
of the engine is shown in Figs. 88 and 89. The following
are the principal dimensions:
Weight of Engine Empty 130,000 Lbs.
" on Drivers 84,000 "
" " Truck 46,000 "
" of Engine in Working Order 145,500 "
" on 1st pair Drivers 48,500 "
"2nd " " 46,700 "
" Truck 50,300 "
Tender Fitted with Scoop.
Capacity of Tender — Water 3,ooo Gals.
" —Coal I5,ooo Lbs.
Weight " " —Empty 37»ioo "
" " " — Loaded 77,000 "
Spread of Cylinders 79 Inches
Distance bet. Centre of Frames 42 "
Width of Cab 9 ft. 7 in.
Height of Cab Roof from Rail (Centre) 14 ft. o in.
Inside Length of Fire-Box 9 ft. o in.
" Width " " 40 Inches
Number of Tubes 289
Length " " 1 1 ft. 9^ in.
Outside Diameter of Tubes i% Inches
Diameter of Drivers, outside of tires 84 Inches
Diameter of Truck Wheels, outside of tires 42 "
Fire Box of Belpaire type.
Grate area 30 square feet
Fire Box Heating Surface 159
Tube Heating Surface 1661 "
Total Heating- Surface 1820 "
Working Boiler Pressure, by gauge 200 Ibs.
Safety Valve set at 205 "
High-Pressure Cylinders K)l/2 X 28 in.
Low-Pressure Cylinders 31 X 28 in.
The main valves are of the piston type, and both are
12% inches in diameter with a maximum travel of 7 inches
in full gear, and are placed between the frames in the saddle.
The section of the valves is reduced near the centre of the
length, and the annular cavity thus formed communicates
with the live steam pipe in the h. p. valve and with the receiver
TWO-CYLINDER RECEIVER COMPOUNDS. IQI
in the 1. p. valve, so that the steam for both cylinders is
admitted at the centre and discharged at the ends of the
valves. The steam admission opening to both valves is 5^
inches wide, and the steam ports leading from valve liner to
both cylinders are 2^ inches wide ; making allowance
for the bridges crossing the port openings the actual length
of the steam ports in the valve seat of both cylinders is 29
inches. The receiver pipe is made of copper and has an
internal diameter of 8 inches.
The cut-off in full forward gear is 22 inches or 78.6 per
cent, of the stroke in h. p. cylinder, and 23.5 inches or 83.9
per cent, of stroke in 1. p. cylinder. The lap on steam side
is 1.53 inches on the h. p. valve, and 1.31 inches on the 1. p.
valve. The clearance or negative lap on exhaust side is
0.625 inch on h. p. valve and' 0.75 inch on 1. p. valve.
The steam admission leads are as follows :
FULL FORWARD GEAR.
H. p. front, 0.115"
H. p. badk, 0.23"
L. p. front, 0.25"
L. p. back, 0.125"
FULL BACK GEAR.
H. p. front, negative 0.70
H. p. back, negative 0.55
L. p. front, negative 0.47
L. p. back, negative 0.70
When in full forward gear the maximum port openings
to steam are :
H. p. cylinder, 1.97
L, p. cylinder, 2.19
and to exhaust :
H. p. cylinder, full
L. p. cylinder, full
When cutting off at 50 per cent, stroke the port openings to
steam are :
H. p. cylinder, 0.98
L. p. cylinder, 1.12
COMPOUND LOCOMOTIVES,
and to exhaust :
H. p. cylinder, full
L. p. cylinder, full
The radius of the link is 51 inches and length of the
connecting rod 7 feet ^8 inches. The receiver volume is
26672 cubic inches, the volume of h. p. cylinder 8362.2
cubic inches and its clearance 1045 cubic inches. The vol-
ume of the 1. p. cylinder is 21 134.4 cubic inches and its clear-
ance 1438.7 cubic inches. H. p. cylinder clearance is 12.28
per cent.; 1. p. cylinder clearance is 6.8 per cent.; ratio
of receiver volume to h. p. cylinder volume is 3.2. The
Lindner device, consisting of a four-way plug cock, is applied
to this engine, the equalization ports in the h. p. valve are
each y3^ inches X I inch and the controlling port in the 1. p.
valve is -fa inches X I ^ inches. The pipe which admits
steam to the four-way cock is connected directly to the
main steam pipe in the smoke box, as has been described
before for the Lindner system, 106.
This engine has 5^-inch inside clearance or negative lap
for h. p. cylinders, J^-inch for 1. p. cylinders, and every
endeavor has been made to get the best possible steam dis-
tribution. The receiver is unusually large, and so far as
can be seen at this time the design of cylinder apparatus is
one that should give a superior steam distribution, and thus
be very economical. Owing to the very liberal clearance,
or negative lap, and the large ports used, the cylinder
power at high speeds should be greater than any other
compound engine locomotive built up to this time. It is
intended with this engine to regulate the power with the
reverse lever and not with the throttle lever at high speeds.
108. The Cooke Locomotive Works System. — An
experimental engine was built by the Cooke Locomotive
Works, Paterson, N. J., to determine the value of the com-
pound system described in the following : It was a two-
cylinder compound with receiver. The cylinders were 19
TWO-CYLINDER RECEIVER COMPOUNDS.
193
and 27 x 24 inches. No intercepting valve was employed.
The details of the starting gear are shown in Figs. 90 and
91. The volume of the receiver was practically the same
as that of the h. p. cylinder. In starting, steam is let into
FIG. 90.
Cooke Starting Gear.
the receiver from the dome, by opening a valve A which is
connected to the throttle lever. Steam passes through a
reducing valve B and is kept by this
valve to the proper pressure. Fig.
91 shows the connection to the
throttle lever. When the throttle is
closed, the small lever C can be
operated and the valve A opened,
but when the throttle is open the
valve C cannot be opened also, as
the lever C is then made inoperative
by the disengagement of its cam
FIG. 91. connection with rods leading to the
Cab Connection, Cooke Gear, throttle lever.
194
COMPOUND LOCOMOTIVES.
109. The Golsdorf (Austrian) System. — The Austrian
Government has made an examination of all the systems of
compound locomotives in use. These examinations were
made by the mechanical engineers connected with the State
Railway system. The reports advised that the increased
cost of maintenance of existing types of compounds would
be too great under the conditions on Austrian roads, and
the matter was dropped for a time ; but was taken up again
after the invention of a simple starting apparatus by C.
Golsdorf, a mechanical engineer connected with the State
Railways. In Austria the coal is inferior, and the Govern-
ment reports state that but 3^ pounds of water are evap-
orated per pound of coal used. This coal being inferior
FIG. 92. FIG. 93.
Golsdorf Starting Gear — Plan of Valve Seat and Valve.
and expensive, the advantage of compounding is somewhat
greater in Austria than in other parts of Europe. The
saving by compounding was found to be about 18 per cent.
Golsdorf's device is constructed as follows : Leading from
the main steam pipe is a i-inch copper steam pipe which
connects with a fitting on the 1. p. steam chest, at which the
current of steam is divided into ^-inch pipes which lead
to two ports constructed in bridges in the main steam port,
as shown in Fig. 92. These ports are about ^ inches long
by ^ inches wide in the direction of the valve travel.
The steam valve, Fig. 93, has a bridge across its centre,
as shown, which covers the small steam ports. This
describes the entire construction or the compound starting
TWO-CYLINDER RECEIVER COMPOUNDS.
gear which is in the 1. p. valve seat. The h. p. valve seat is
constructed as usual. The valve motion is the Walscheart,
which has been chosen because it gives a longer maximum
cut-off than the ordinary link motion. By it is obtained
a maximum cut-off of 92 per cent. The operation of this
system is as follows :
When the reverse lever is in full gear, or nearly so, the
valve travel is such as to uncover the small port whenever
the 1. p. cylinder is to furnish the power for starting, and in
this way steam enters from the main steam pipe, when the
throttle is open, to the 1. p. cylinder steam chest and
receiver. When the start is to be made by the h. p.
cylinder, the 1. p. slide valve is in such position as to cover
the small port and prevent the entrance of steam from the
steam pipe into the 1. p. cylinder. When the engine is
started, the driver hooks up the reverse lever, which reduces
the valve travel and the small ports are not uncovered.
With this gear, which is not unlike the Lindner, the maxi-
mum starting power can only be obtained during the first
revolution, or, more correctly, during a part of the first
revolution. The first of these engines was built in 1892.
Since then five others have been ordered. A general
description of the engines is given in Table C C, Appen-
dix R.
CHAPTER XVII,
DESCRIPTION OF TWO - CYLINDER RECEIVER COMPOUNDS
WITH INTERCEPTING VALVE AND WITH SEPARATE
EXHAUST FOR HIGH - PRESSURE CYLINDERS AT START-
ING.
110. The Mallet System. — This system is non-auto-
matic, by which is meant that the change from the use of
h. p. steam in the 1. p. cylinder to full compound action is
made at the will of the engineer and not automatically.
This system has suitable valves so that the engine may be
operated as a single expansion engine, not only in starting
but at any time when in service. Such an engine, while
having all the advantages ok compound working, possesses
an emergency power equal, or possibly superior to, a single
expansion engine having the same general dimensions.
Figs. 94 to 99, inclusive, illustrate the arrangement of
this system as applied to a converted six-coupled engine of
the Western Switzerland Railroad.
In Fig. 94, h and / are the h. p. and 1. p. cylinders,
respectively. A is the main steam pipe from the boiler to
the h. p. cylinder, B is the receiver, C is the 1. p. exhaust
pipe, D is the starting valve which is connected to the boiler
by the pipe E, F is the intercepting valve, and G is the
exhaust pipe from the h. p. cylinder when working as a
single expansion engine.
The construction of the starting valve is shown in Figs.
95 and 96. It consists primarily of a short slide valve a,
which, as shown, covers two ports leading to the receiver.
The pipe p connects the starting valve chamber with the
main steam pipe. On the back of the valve a is an inverted
slide valve £, which slides on a seat formed in the valve-
196
TWO-CYLINDER RECEIVER COMPOUNDS.
IQ7
chest cover. A small pipe c connects the starting valve
chamber with the intercepting valve on the other side of
the smoke box, as shown at c, Fig. 97. Referring now to
FIG. 94.
Mailet Starting Gear — Arrangement of Parts.
• FIG. 95.
Mallet Starting Gear — Detail of Starting Valve.
Fig. 97 it will be seen that the intercepting valve consists
of two circular valves and a piston, all being mounted on
one stem, and so forming a sort of balanced double poppet
valve. The connections to the intercepting valve are as
IQ8
COMPOUND LOCOMOTIVES.
indicated in the figure, the central opening connecting with
the h. p. exhaust, the left with the common exhaust nozzle
and the right with the receiver pipe.
FIG. 96.
Mallet Starting Gear — Detail of Starting Valve.
FIG. 97.
Mallet Intercepting Valve.
The operation of these valves is as follows : They are
shown in the illustrations in the positions which they
ordinarily occupy, or when the engine is working as a com-
4
TWO-CYLINDER RECEIVER COMPOUNDS.
pound. Under these circumstances steam from the boiler
is admitted to the space d back of the piston e by way of
the small pipe c, the starting valve chamber, and the pipe
p. The pressure thus acting upon the piston e keeps the
valve g closed against the ordinary receiver pressure. The
intercepting valve can, of course, be connected so as to be
worked by hand in connection with the starting valve. If
now the starting valve is opened, or moved to the right in
Fig. 95, steam from the boiler is thereby admitted to the
receiver, and at the same time the pipe c is placed in com-
munication with the atmosphere by means of the cavity in*
the top of the starting valve. The pressure back of the
piston e being thus reduced, the valve g is opened by the
receiver pressure, and the valve h is closed, in which position
it is retained by the excess of the pressure in the receiver,
Fig. 97, or that on the 1. p. side of the valve, over that
on the h. p. side which is now in communication with the
exhaust nozzle. It will be seen that the locomotive will
now work as a single expansion engine, and will continue
to do so as long as the starting valve is kept open. As
soon as it is closed the intercepting valve will be returned
to the position shown in Fig. 97.
On the engine illustrated by Fig. 94, a pressure-redu-
cing valve is inserted between the starting valve and the
receiver. This reducing valve is of the common differential
piston type, adjusted by springs. In addition to this the
receiver is fitted with a spring safety valve loaded to 70
pounds pressure. It would seem when a starting valve of
this form is used in conjunction with a safety valve, that the
introduction of a reducing valve is unnecessary, as the
receiver pressure can be regulated by the starting valve.
111. The Early Form of the Mallet System.— In
earlier designs Mr. Mallet has combined the starting and
intercepting valve in one distributing valve. This is illus-
trated by Figs. 98 and 99. The distributing valve and a
2OO
COMPOUND LOCOMOTIVES.
reducing valve are enclosed in a casing which is fastened
to the smoke box. The main steam pipe is connected at a,
and thence by a passage b, back of the valves, to the h. p.
steam chest. An opening at c admits steam from this pipe
to the reducing valve chamber and thence to the distribut-
FIG. 98.
Mallet Distributing Valve.
FIG. 99.
Mallet Distributing Valve.
ing valve chamber, The distributing valve is a slide valve,
and covers three ports, as shown. Of these d is the h. p.
exhaust, e connects with the receiver, and hence with the
1. p. steam chest, and g leads to the exhaust nozzle. The
^alve is shown in the position for compound working. If
TWO-CYLINDER RECEIVER COMPOUNDS.
201
it is moved forward, or to the left in the illustrations, the
passage d is connected with g, and the h. p. cylinder
exhausts directly to the exhaust nozzle, and at the same
time by means of the passages c and e boiler steam at
reduced pressure is admitted to the receiver and the 1. p
steam chest.
FIG. 100.
Mallet's Proposed Double Low- Pressure Cylinder.
FIG. 101.
Mallet's Proposed Double Low-Pressure Cylinder.
The earlier forms of intercepting valves were not wholly
automatic in their action, but required to be closed by hand
before opening the throttle in starting. In this form there
were no small plungers, and the steam was admitted around
2O2 COMPOUND LOCOMOTIVES.
the valve stem k, which was fluted for part of its length for
this purpose. The valve was also connected by a bell-crank
arrangement to a weighted arm, which held the valve open
and prevented rattling when running with steam shut off.
112. Preliminary Work of Mallet. — The earliest work
of real practical value in compound locomotive designing
was done by Mr. Mallet. Two of his most important con-
tributions to the subject are the separate exhaust of the
h. p. cylinder at starting, previously described, and the
double 1. p. cylinder, Figs. 100 and 101. The object of this
double 1. p. cylinder is to give to the nominally two-cylinder
type the necessary volume of 1. p. cylinder without exceed-
ing the maximum width allowable for locomotives.
113. Rhode Island Locomotive Works (Batchellor)
System. — The Rhode Island Locomotive Works, or
Batchellor, system is shown in Figs. 102, 103 and 104.
The following is the construction and operation : Fig. 102
shows the front section of intercepting valve at ports d and
e, also front view of portion of receiver with exhaust valve.
Fig. 103 shows side section of intercepting valve while run-
ning compound. Fig. 104 shows side section of intercept-
ing valve when engine is operating with independent
exhaust for h. p. cylinder. A is the intercepting valve
casing, B is the reducing valve, C the oil dash-pot, D is a
pipe from main steam pipe to intercepting valve, E is the
receiver, F is the exhaust valve leading to atmosphere from
receiver, a, b and c is the intercepting valve piston, d is a
port leading from D to through the casing of the intercept-
ing valve, D being the pipe from the main steam pipe to
intercepting valve, e is a port from intercepting valve
casing to the reducing valve B. There is a port from the inter-
cepting valve casing into the passage leading to the 1. p.
steam chest, m is the crank which operates the exhaust
valve leading from the receiver to the atmosphere, o and o
are ports leading through the exhaust valve F and its seat.
TWO-CYLINDER RECEIVER COMPOUNDS. 2O3
FIG. 102.
Rhode Island Locomotive Works (Batchellor) Starting Gear — Cross Section
Through Intercepting Valve and Separate Exhaust Valves.
FIG. 103.
Longitudinal Section Through Rhode Island Locomotive Works (Batchellor)
Intercepting Valve — Valve Open.
2O4 COMPOUND LOCOMOTIVES.
The operation of the device is as foltows : The inter-
cepting valve being in any position, as in Fig. 103, and
the exhaust valve closed, the throttle being opened,
boiler steam will pass to the h. p. cylinder in the usual
manner, and also through pipe D into the intercepting
FIG. 104.
Longitudinal Section Through Rhode Island Locomotive Works (Batchellor)
Intercepting Valve — Valve Closed.
valve A, causing the piston to move into the position shown
in Fig. 104. In this position the receiver is closed to the
1. p. cylinder by the piston C, and steam from D passes
through ports d and e, and reducing valve B, into the 1. p.
steam-chest ; the pressure being reduced from boiler pres-
sure in the ratios of the cylinder areas. The piston a-b-c,
is so proportioned that it will automatically change to the
compound position shown in Fig. 103, when a predeter-
mined pressure in the receiver E has been reached by
exhausts from the h. p. cylinder. The engine thus starts
with steam in both cylinders, and automatically changes to
compound at a desired receiver' pressure.
The engine may be changed from the compound system
to the single expansion at any time, at the will of the
engineer, by opening the valve F connecting the receiver to
the exhaust pipe, allowing the exhausts from the h. p. cyl-
inder to escape through the nozzle in the usual manner.
The exhaust valve .F is operated as follows: The lever
m, which rotates the exhaust valve F, is connected by a rod
to a handle in the cab. To run compound place lever m as
TWO-CYLINDER RECEIVER COMPOUNDS. 2O5
"
shown on the left in Fig. 102, which closes ports o. To
run single expansion place lever m as shown on the right
in Fig. 1 02, the ports o opening E to exhaust.
It is obvious that, in case of bad conditions of starting,
the engine may be operated single expansion at the will of
the engineer by opening the exhaust valve before starting,
and that upon its closure the piston a-b-c will automatically
take the compound position of Fig. 103.
This system can be used either as automatic or non-
automatic as desired.
The Rhode Island Locomotive Works claim the follow-
ing for their system of starting gear :
(1) Compound engine automatically adapted to all requirements of variable
service.
(2) All necessary devices by which a locomotive may be run at any time and at
any place on the road, and for any length of time demanded by the service, as a single
expansion engine; each cylinder doing exactly halt the work, whatever that may be,
and without waste of steam.
(3) The engineer, at any time he chooses, may change the engine into compound
working, permitting it to operate thus as long as circumstances will require, and then
he may change it back again at once into single expansion working. These changes
are made as easily as the engineer turns his hand to open or close one valve, by a
convenient lever in the cab, and can be done when the engine is standing or in
motion.
(4) Great simplicity in form and number of working parts, and whose steam-ways
are most uniform in section and most direct in course from boiler to point of applica-
tion.
(5) Ability to run as a single expansion locomotive in case of break down with no
more trouble than an ordinary locomotive.
The use of an independent exhaust for the h. p. cylinder
has made these engines well adapted for elevated railroad
service. This company has built on this plan a number
of engines that are in successful service, see Table CC,
Appendix R.
114. The Richmond Locomotive Works (Mellin)
System. — This system is strictly automatic under ordinary
conditions ; that is, the use of steam directly from the boiler
into the 1. p. cylinder, is shut off whenever the exhaust
pressure from the h. p. cylinder accumulates in the receiver
2O6 COMPOUND LOCOMOTIVES.
to a point where it will actuate the automatic mechanism.
But it also has what the inventor calls an "emergency"
valve, and by it the engineer can open a separate exhaust
for the h. p. cylinder for a sufficient period at starting
to get the train under way. At this writing the patents
for this device have not been granted, and it has been
deemed inadvisable to publish the drawings. The fol-
lowing is, however, a general description:
In the cylinder saddle there is a small piston with a
dash-pot connected to the piston rod which controls an
intercepting valve placed horizontally. The intercepting
valve shuts off the steam, that is admitted to the 1. p. cyl-
inder at starting, from entering the receiver. Surrounding
the small piston just mentioned is an annular sleeve or
piston which serves as a reducing valve. The emergency
valve consists of a plain, bevel-seated valve attached to a
piston which is connected on one side to a live steam pipe
leading to a valve in the cab. This piston is returned to
its seat by a spring on the piston rod. The device operates
as follows:
Steam from the main steam pipe acts upon the annular
piston around the intercepting valve stem and forces the
intercepting valve to its seat, thus closing communication
between the 1. p. cylinder and' the receiver. At the same
time the sleeve or annular piston opens a small port which
admits steam to the 1. p. cylinder directly from the main
steam pipe. This sleeve then acts as a reducing valve.
The intercepting valve is prevented from slamming by the
air dash-pot on the end of the stem. When the intercepting
valve is closed the exhaust from the h. p. cylinder accumu-
lates in the receiver, and pushes the intercepting valve back
to an open position and the engine works compound.
When it is desired to work with a separate exhaust for
the h. p. cylinder the engineer opens a valve in the cab and
admits steam back of the piston, which is connected with
TWO-CYLINDER RECEIVER COMPOUNDS.
2O7
the emergency valve. The pressure on the piston forces
the emergency valve open. This opens communication
from the receiver to the atmosphere, and gives a separate
exhaust for the h. p. cylinder. When running, the engine
can be changed from compound to non-compound by open-
ing the valve in the cab. This system then, can be used as
either automatic or non-automatic, as desired.
115. The Pittsburgh Locomotive Works' (Colvin)
System. — Figs 105 to 107 show the non-automatic inter-
cepting and reducing valve used by the Pittsburgh LOCO-
FIG. 105.
Arrangement of Cylinders and Intercepting Valve, Pittsburgh Locomotive
Works (Colvin) System.
motive Works on several two-cylinder compounds which
they have built. This reducing non-automatic intercepting
valve is placed in the h. p. cylinder saddle, as shown in
Fig. 105, and is so arranged that the engineer, by moving
the lever in the cab, can open an independent exhaust for
the h. p. cylinder through passage Fig. 106, to the
stack. When it is desired to run compound the lever is
again moved and the intercepting valve is open. In Fig.
107 the intercepting and reducing valve are shown when in
'the position to work compound.
208
COMPOUND LOCOMOTIVES.
In this system steam from the steam pipe in the h. p.
cylinder saddle passes to the reducing valve through a
small passage shown in Figs. 106 and 107. When the
reducing valve is permitted to open, as it is in Fig. 106 by
the removal of the intercepting valve to the right, steam
passes directly through the reducing valve as shown by the
FIG. 106.
Pittsburgh Locomotive Works System — Separate Exhaust for High-Pressure
Cylinder, Open.
FIG. 107.
Pittsburgh Locomotive Works — Separate Exhaust for High-Pressure
Cylinder, Closed.
arrows from the h. p. steam pipe to the receiver thence to
1. p. cylinder. The amount of reduction of pressure by the
reducing valve depends upon the ratio of the areas of the
piston of the reducing valve and the area of the valve
itself.
When the engine is to be run compound the engineer
TWO-CYLINDER RECEIVER COMPOUNDS. 2OQ
forces the intercepting valve back to. the position shown in
Fig. 107 by means of a rod which is connected to a
lever in the cab. The movement of the intercepting valve
to the left forces the reducing valve to its seat as shown in
Fig. 107 and permits the h. p. cylinder to exhaust into the
receiver. When in the non-compound position, shown in
Fig 1 06, the h. p. cylinder exhausts directly to the atmos-
phere as indicated in Fig. 105.
The engines that have been built with this gear up to
this time are given in Table C C, Appendix R.
116. von Berries' Latest System. — After a number of
years' experience with automatic starting gears that give
increased power to compound locomotives during a part of
the first revolution, Mr. von Borries has reached the impor-
tant conclusion that an independent exhaust with an h. p.
cylinder, such as used by Mallet, is necessary for two-
cylinder receiver compounds with cranks at right angles
when the locomotive has to start heavy trains or work on
comparatively heavy grades. Mr. von Borries' device for
accomplishing this is as follows :
A double piston valve having a piston rod with a reduced
section, which serves as a reducing valve, operates horizon-
tally in a chamber on top of the h. p. steam chest. The
chamber has three main passages, one leading to the receiver,
one leading to the h. p. exhaust, and a third leading to the
atmosphere. This last is the independent exhaust for the
h. p. cylinder. This chamber also has a passage connected
with a comparatively small pipe leading to the h. p. steam
pipe. Through this passage comes the steam that goes
directly to the receiver and 1. p. cylinder at starting. When
the piston is at one end of the stroke the exhaust passage
from the h. p. cylinder to the atmosphere is open. When in
the other extreme position, the separate exhaust is closed
and the passage is open through which the h. p. cylinder
exhausts into the receiver. The movement of the piston
2IO COMPOUND LOCOMOTIVES.
is accomplished by a steam pressure which is admitted at
one end of the double piston through a small valve that is
actuated by a lever from the cab. The steam enters the
small valve from the h. p. steam pipe through a small copper
pipe connecting the two. The piston is cushioned at each
end of the stroke by the steam that is being used, and no
dash-pots are necessary. At starting the engineer moves
a lever in the cab which admits steam back of the piston
and closes the intercepting valve and opens the exhaust
from the h. p. cylinder to the atmosphere for as long a
period as may be desired at starting.
The reducing valve is a part of the stem of the double
piston, thus no separate piece is used for it. Drawings
are not obtainable at this writing on account of patent
complications,
CHAPTER XVIII.
DESCRIPTION OF FOUR-CYLINDER NON-RECEIVER COMPOUNDS,
"CONTINUOUS" EXPANSION OR WOOLF TYPE. VAUCLAIN
AND NON-RECEIVER TANDEM TYPES.
117. The Dunbar System. — A four-cylinder compound
locomotive was built by the Boston & Albany Railroad Com-
pany in 1883, under the Dunbar patents. The cylinders
were 12 inches and 20 inches in diameter, by 26 inches
stroke, and were arranged tandem with the h. p. and 1. p.
pistons on the same piston rod. The engine could be worked
compound or non-compound at will. After working about
seven months the locomotive was changed to a single expan-
sion engine as it was apparently no more economical than
the single expansion locomotives. It is stated that the ports
were too small and that the inventor was absent during the
trial. As the locomotive was an experiment, it is not sur-
prising under the circumstances that the results were unsatis-
factory.
118. The Du Bousquet ( Woolf) System on the North-
ern Railway of France. — A successful application of the
tandem form of compound engine to a locomotive has been
made by Mr. G. Du Bousquet, of the Northern Railway of
France. This locomotive is an eight-coupled outside con-
nected engine, all of the weight being on the driving wheels.
It was originally a single expansion locomotive, having
cylinders 19.68 inches in diameter by 25.59 inches stroke.
The boiler pressure of 142.2 pounds, gauge, is the same as
before converting it. The principal dimensions of this
locomotive are as follows :
211
212
COMPOUND LOCOMOTIVES.
Diameter of high-pressure cylinders
" " low-pressure
Stroke of pistons
Diameter of driving wheels
Total weight, all on driving wheels.
Area of grate
Total heating surface
15 inches.
26
25.6 "
51.2 "
1 13,970 pounds
22.4 sq. ft.
1,356 " "
The changes in the distribution and amount of the
weights on the axles on account of converting are given as
follows :
Simple. Compound.
First axle 26,900 29,670
Second axle 24,470 31,390
Third axle 26,670 30,820
Fourth axle 20,500 22,090
Total 98,540
113,970
FIG. 108.
Cylinders and Steam Chest of the Du Bousquet Type.
To balance the increased weight of the cylinders a foot
board weighing 6,600 pounds was put in. Fig. 108 illus-
trates the arrangement of the cylinders and valve chest,
and is worthy of careful examination. It will be seen that
the steam distribution for both cylinders is controlled by
one valve, the 1. p. valve being, as it were, inside of the
h. p. valve. The arrows clearly indicate the paths of the
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 213
steam. ' The principal dimensions relating to this valve gear
are as follows :
Travel of valve
Steam lap, both cylinders, front
" " " back
Exhaust lap, high-pressure
" low pressure ......
6.22 ins.
1.34 "
1.22 "
o.oo "
0.32 "
Ports, high-pressure steam ......................... 17-72 ins. X 1.38 "
" Jow-pressure " .......................... 17-72 " X 1.97 "
exhaust .................. ...... 17.72 " X 3-54 "
Angular advance of eccentrics ...................... 30 deg.
Clearance, per cent., of cylinder volume h. p ........... 15.4
" " " " " 1- P ........... 7-0
Volume of connecting passages, per cent, of h. p. volume 16.5
The features of this design which are specially note-
worthy are that the dead space between the cylinders is
reduced to a minimum, the h. p. clearance space is large,
and that there are no bushings between the cylinders, but
instead there are outside stuffing boxes which are easily
accessible.
119. Indicator Cards from the Du Bousquet (Woolf)
Compound.— The indicator cards shown by Figs. 109 to
113, inclusive, illustrate the steam distribution in this loco-
H45.
FIG. 109.
Indicator Card at Slow Speed, from Du Bousquet Type.
motive. The effect of piston speed upon the distribution
is well illustrated by Figs, no and 112, which were taken
at the same nominal point of cut-off, but as the two pairs
214
COMPOUND LOCOMOTIVES.
of cards are apparently from opposite ends of the cylinders,
it is probable that the great increase in compression shown
in Fig. 112 is partially due to irregularity in the valve
motion. The mean pressures in these diagrams and the
percentage of the total work done in the h. p. cylinder are
as follows :
Mean pressure.
H. p. L. p.
Fig. 109 79.36 30.87
" no 63.01 21.76
III 51-20 15.36
" 112 , 36.84 15.22
" 113 31-86 9-53
Per cent, of work
done in h. p.
46.2
49.1
52-6
44-7
52.7
145,
Indicator Card,
FIG. no.
Cut-Off, Du Bousquet Type.
-(45.
Indicator Card,
FIG. in.
Cut-Off, Du Bousquet Type.
This locomotive has been carefully tested in comparison
with a single expansion locomotive belonging to the same
original class. The compound hauled trains about 12 per
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 2 1 5
cent, heavier than the single expansion locomotive, with a
noticeable saving in fuel, while with trains of the same
weight the saving in fuel, as reported by Mr. Du Bousquet,
was from 13.5 to 25.8 per cent. The average of five tests
is 21.9 per cent.
FIG. 112.
Indicator Card, -ffa Cut-Off, Medium Speed, Du Bousquet Type.
FIG. 113.
Indicator Card, TVu Cut-Off, Slow Speed, Du Bousquet Type.
120. Baldwin Locomotive Works (Vauclain) System.
—The first locomotive of this type was built by the Bald-
win Locomotive Works in the fall of 1889, and was put to
work on the Philadelphia Division of the Baltimore & Ohio
Railroad. The general arrangement of the cylinders and
valve is shown by Figs. 114 to 123. The method by which
the power from both cylinders is transmitted through one
crosshead is shown in Figs. 118 and 119, which also shows
216 COMPOUND LOCOMOTIVES.
the direct connections of the valve. The steam distributing
m *
FIG. 114.
Vauclain Cylinders with High-Pressure Above.
FIG. 115
Vauclain Cylinders with Low-Pressure Above.
valve is a hollow piston valve, the action of which is
illustrated by Fig. 120.
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 217
The cylinders are arranged two on each side, with the
1. p. cylinder directly above or below the h. p. cylinder,
depending upon the service and the clearances and conditions
FIG. 1 1 6.
Vauclain Piston Valve.
to be met. The main valve chamber, which replaces the
steam chest of the ordinary h. p. locomotive, is cast in one
FIG. 117.
Vauclain Piston Valve Bushing.
piece with the cylinder casting and is placed as near the
cylinders as possible in order to give short steam passages.
The by-pass, or starting valve, is located below the
cylinders and main valve. This starting valve is not con-
nected in any way with the valve gear of the locomotive,
218
COMPOUND LOCOMOTIVES.
and is operated from the cab by a small lever located near
the reverse lever.
In order to illustrate more clearly the passage of steam
through the steam valve to and from the cylinders, the main
valve is shown in Fig. 120 as being between the cylinders.
For the same reason the starting valve is shown between the
cylinders, Figs. 121, 122 and 123.
FIG. i i 8.
Arrangement of Crosshead, Guides and Piston, Vauclain Type.
In this design, at the present time, the air valve, shown
in Fig. 116, on the end of the piston valve, is no longer
used.
From Fig. 120 it is seen that the steam valve, shown
between the cylinders, is a hollow piston with solid ends.
A cavity extends around the middle of the valve. The
passages and ports lettered A are connected directly with
the steam pipes leading from the boiler to the valve chamber ;
those lettered B are ports and passages leading from the
steam valve to the h. p. cylinder, and those lettered D con-
nect the steam valve with the 1. p. cylinder. C is the final
exhaust passage to the atmosphere.
With the valve, as shown in Fig. 120, the steam, at boiler
pressure, is entering the valve chamber at the port A on the
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 2IQ
left of the figure, and as the end of the valve does not cover
the port B on the left, the steam passes from A to B and so
into the front end of the h. p. cylinder, where it expands
during the time the port is closed by the valve.
At this time in the back end of the h. p. cylinder there
is steam that has been used in expansion and is ready for
exhausting into the 1. p. cylinder. It now passes through
FIG. 119.
Vauclain Crosshead.
the passage B on the right, to the steam valve and to the
inside of the valve, where it passes from the back end to the
front end of the valve into the passage D on the left of the
figure, and thence into the front end of the 1. p. cylinder, as
shown by the arrows.
In the back end of the 1. p. cylinder is steam that is
ready for exhausting into the stack. It has been used in
the 1. p. cylinder. It now passes from the back end of the
1. p. cylinder through the passage D, on the right, to the
cavity around the steam valve, thence to the exhaust passage
and to the atmosphere, as shown by the arrows.
220
COMPOUND LOCOMOTIVES.
FIG. 120.
Steam Distribution, Vauclain Type.
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 221
The simultaneous action of the steam in both ends of
both cylinders is as follows : While steam is entering the
front end of the h. p. cylinder direct from the boiler past
the end of the steam valve, the steam in the back end is
exhausting through the steam valve to the front end of the
1. p. cylinder, and the steam from the back end of the 1. p.
cylinder is exhausting into the cavity around the valve, and
thence to the exhaust pipe and the atmosphere. This is
the course of the steam in the cylinders when the engine is
working compound, and, with the exception of the small
jet of high pressure steam admitted through the by-pass
valve, the same course is followed by the steam when the
engine is working in what is called " high pressure."
To make as plain as possible the course of the steam
when the engine is working with some of the high pressure
steam in the 1. p. cylinder, reference is made to Fig. 120.
Suppose a pipe to connect the passages B B, and to have a
valve in it ; now, if the valve is open, as it is when the lever
in the cab is in its middle or front position, steam can pass
freely through the valve and pipe from one passage B to
the other B and balance the h. p. -piston. Now this is
exactly what takes place when the by -pass valve is used,
and it is done as follows :
Steam passes from the boiler into the steam valve cham-
ber, and continues on into the steam passages of the h. p.
cylinder. A large part of this steam continues on to the
1. p. cylinder, just as when the engine works compound, but
the remainder of the steam passes through the pipe and
starting valve to the back steam passage B on the right
of Fig. 120, mingling with the steam that is exhausting from
the back end of the h. p. cylinder, and thence to the front
end of the 1. p., thus increasing the pressure of steam on
the 1. p. cylinder. This increase goes on until the engine
starts. After the engine starts the pistons move so rapidly
that the small opening in the by-pass valve cannot supply
222
COMPOUND LOCOMOTIVES.
steam fast enough to keep up the pressure. If the engine
does not start readily the pressure in the 1. p. cylinder goes
on increasing until it reaches boiler pressure. It will be
seen that back pressure in the h. p. cylinder is increased by
FIG. 121.
Starting Valve and Cylinder Cocks, Vauclain Type.
Starting Valve Open and Cylinder Cocks Closed.
this, and therefore the work done in the h. p. cylinder is
less, under these conditions, than when the engine is
working compound, but the work done in the 1. p. cyl-
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 223
inder is much greater than when working compound.
The piston in the 1. p. cylinder being of greater area than
that in the h. p. cylinder, the combined effort of the two
FIG. 122.
Starting Valve and Cylinder Cocks, Vauclain Type.
Starting Valve Closed and Cylinder Cocks Closed.
pistons is much greater when the engine is working with
some h. p. steam entering the 1. p. cylinder than when
working compound.
224
COMPOUND LOCOMOTIVES.
The steam passing through the by-pass valve, when the
engine is working " high pressure," acts just as a leak past
the h. p. piston would act..
The operation of the starting, or by-pass valve, will be
FIG. 123.
Starting Valve and Cylinder Cocks, Vauclain Type.
Starting Valve Open and Cylinder Cocks Open.
understood by referring to Fig. 121. On the right of the
figure is a small diagram showing the positions of the lever
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 225
in the cab, the full line corresponding to the position of
the lever when the valve bears the same relations to the
ports, as shown in the illustration. It will be seen that in
this position of the valve, steam can pass freely from one end
of the h. p. cylinder, through the ports, into the inside of the
starting valve, and so on to the steam passage leading to
the other end of the h. p. cylinder. This is the position of
the valve when the engine is working with some of the
h. p. steam passing to the 1. p. cylinder.
Fig. 122 shows the position of the starting valve when
the engine is working compound, all the ports being covered,
no steam is passing through the valve. The full line in
the diagram at the right shows the position of the lever in
the cab, the right of the figure being toward the back end
of the engine.
In Fig. 123 is shown the position of the valve and of
the lever in the cab, when the cylinder cocks and starting
valve are open. In this position there is free communica-
tion between both ends of both cylinders, and the cylinder
cock drain pipe, through the centre of the valve. This
allows the cylinders to be drained, as shown clearly by the
arrows. But, of course, the drain pipe is lower than the
h. p. cylinder, and not above it, as is here shown for the
purpose of giving a readily understood explanation.
Figs. 124 to 126 show a new type of air valve and cyl-
inder drain cock that has just been introduced fpr this type
of engine. The experience with it is limited at this time,
but it promises well, and is easily accessible. The body of
the cock is in one casting, into which are put the two taper
plugs, one of which, X, Fig. 125, controls the steam for
starting, and the other, Z, controlling the 1. p. cylinder cock.
The passage leading to the cock X is connected to opposite
ends of the h. p. cylinder, and those from plug Z lead to
opposite ends of the 1. p. cylinder. The two cocks have a
squared end upon which is one arm which operates the two
226
COMPOUND LOCOMOTIVES.
cocks simultaneously. In position No. i. the plug X allows
steam to pass through, putting in communication the
opposite ends of h. p. cylinder, thence through valve to
effective side of 1. p. piston; all the openings in cock Z
being closed. When the arm is moved to position No. 2,
FIG. 124.
Recent Form of Starting Valve and Cylinder Cocks, Vauclain Type.
the opening in plug X allows the steam to pass through as
before, but it also brings hole G opposite hole H, allowing
any water to escape from h. p. cylinder to atmosphere.
Plug Z, with arm in position No. 2, allows the three open-
ings in the plug to come opposite the three openings in the
body, thus draining the 1. p. cylinder. The arm in position
No. 3 closes all openings and is the running position. The
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 227
r
FIG. 126.
Details of Recent Form of Starting Valve
and Cylinder Cocks, Vauclain Type.
226 COMPOUND LOCOMOTIVES.
cock is operated from the cab by a lever with a notched
quadrant, corresponding to the three positions of the arm.
The starting valve and cylinder cock is applied to the cyl-
inder, as shown in Fig. 124.
121. Distribution of Pressure on Pistons. — The
feature of this design, which at first glance would seem to
be most open to criticism, is the connection to one cross-
head of two pistons, of which the centres are about 18
inches apart and on which the total pressures must differ
considerably. To determine the amount and variation of
this difference of pressure with reasonable exactness an
examination of a very large number of indicator cards taken
simultaneously from both h. p. and 1. p. cylinders would be
necessary, and the inertia of the reciprocating parts must
be taken into account. See Appendix P. Some knowledge
of the subject can, however, be gained from an examination
of the indicator diagrams shown in Figs. 1 1 and 12. The
data for these diagrams is given in Table DD. The dia-
grams were divided into ordinates as shown in Figs. 127
and 128, and the difference between the forward pressure
on one side of the piston and the back pressure on the
other side was plotted for each ordinate, allowance being
made for the piston rod areas. When the starting valve is
opened these results will be materially altered. The inertia
of the reciprocating parts was calculated for the different
points of the stroke. See Appendix P.
From these results the curves shown by the heavy full
lines in Figs. 127 and 128 were plotted. These curves
indicate very closely the actual pressures on the crosshead,
where the piston rods are attached for the h. p. and 1. p.
cylinders, at different parts of the stroke, the inertia of the
reciprocating parts being taken into account. The num-
bers on the diagrams refer to the correspondingly numbered
indicator cards of Figs. 1 1 and 12.
The full line on Figs. 127 and 128 shows the difference
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 22Q
TABLE D D.
Giving Data for Indicator Cards showing Steam Distribution on Baldwin
Compound, on C. M. &= St. P. Railway. See Figs. 127 and 128.
Card
1 -""
•L«
Miles
Cut-off in
Inches.
Mean Effective
Pressure.
tjj gu
Horse-Power.
?fe
No.
<u s «
IsJ
per
W 5(2^
u^a*'
i"0
Hour.
H. P.
L. P.
H. P.
L.P.
llS-B
H. P.
L. P.
£|J
F i
i76
256
47.10
12.25
15.06
37-50
13-75
40.43
142.4
145-2
5°.
B 2
176
256
47.10
12.25
15.00
41.25
12.50
34-75
141.4
127.3
47-
F 3
170
228
41-95
12.25
15.06
40.00
15.00
44.10
I35.3
141.1
51-
B 4
170
244
44.90
13-25
15-94
51.88
15.00
41.70
169.4
145.6
46.
F 5
168
232
42.69
13.28
15.90
47-50
20.00
58.80
162.9
191-3
54-
F 6
174
140
25.76
13.28
15.90
64.50
25.00
73-50
134.0
144-5
52-
B 7
177
1 88
34-59
14-25
16.87
68.75
22.50
62.55
i73-o
168.3
49-
F 8
192
35-33
17.62
70.00
28.75
84.52
199.7
227.7
53-
B 9
177
172
3I-65
15-44
17-75
75-00
25.00
69.50
172.7
171.1
B 10
171
156
28.70
15-44
17-75
78.75
27.50
76.45
164.4
170.7
Si-
F n
T75
120
22.08
17-63
82.50
37-50
110.25
146.9
175-6
34-
F 12
170
80
14.72
15.41
17-63
81.25
38.75
ii3-93
96-4
127.8
57-
B 13
176
48
8.83
21.26
22.75
116.25
46.25
128.56
74-7
88.3
54-
between the actual pressure on the crosshead due to the
h. p. piston, and that due to the 1. p. piston. The vertical
distances above the neutral line A A to the full curved line
represent the excess of the total pressure on the h. p. piston
above that on the 1. p. piston. Distances below this line
indicate how much the total pressure .upon the 1. p. piston
exceeds that on the h. p. piston. The scale of pressures is
given on the side of the diagram. It will be seen that the
greatest difference in pressure is for the diagram taken at
slow speed and late cut-off, and that for high speed and early
cut-off the difference is comparatively small. Also that the
effect of higher speed and lower initial pressure with the
same cut-off is to greatly change the amount and distribu-
tion of the excess pressure. The tendency is to tip the
crosshead, and hence to bring a bending load on the piston
rods. It does not follow that this fact is an argument
against the adoption of this design, but simply that a vary-
ing load, acting with a leverage of about 18 inches, and
having from 300 to 600 reversals per minute at ordinary
speeds, should be provided for in addition to the usual
stresses on piston rods.
The lines on diagrams, Figs. 127 and 128 have the
following signification : The dotted lines show the total
230
COMPOUND LOCOMOTIVES.
steam pressures on the pistons of the h. p. and 1. p.
ders, deducting the back pressure. The h. p.
pressures are laid out above the line AA and the 1. p.
cylin-
piston
piston
FIG. 127.
Diagrams showing Total Steam Pressure on High and Low-Pressure
Pistons at Different Points in the Stroke in a Vauclain Compound. Also
showing the Inertia of the Pistons and Piston Rods and the Total Comparative
Pressures on the Top and Bottom of the Crosshead, Taking into Account the
Inertia of the Pistons and Piston Rods.
The Scale at Side of Diagram is in Thousands of Pounds.
pressures are laid out below the line AA. The forward
stroke leads from left to right and the back stroke from
right to left. The straight dotted lines represent the inertia
of the piston and piston rod and do not include the inertia of
the crosshead and main rod. The full fine lines represent
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 231
the combined effect of the steam pressure and inertia of the
piston and rod. The heavy full lines represent the differ-
ence between the pressures on the h. p. and 1. p. pistons at
FIG. 128.
Diagrams showing Total Steam Pressure on High and Low-Pressure
Pistons at Different Points in the Stroke of a Vauclain Compound. Also
showing the Inertia of the Pistons and Piston Rods and the Total Comparative
Pressures on the Top and Bottom of the Crosshead, Taking into Account the
Inertia of the Pistons and Piston Rods.
The Scale at Side of Diagram is in Thousands of Pounds.
the crossheads. The scale at the side of the diagram
indicates the total difference in pressure, and shows the
amount of the twisting tendency on the crosshead for the
different parts of the stroke and under different conditions.
232 COMPOUND LOCOMOTIVES.
The indicator cards from which these diagrams were taken
are from a ten-wheel Vauclain compound on the Chicago,
Milwaukee & St. Paul Railroad, and the data regarding the
cards is given in Table D D, the cards themselves are given
by Figs. 1 1 and 12.
122. Advantages Claimed for the Baldwin Loco-
motive Works (Vauclain) System. — The claims made
by the Baldwin Locomotive Works for the Vauclain com-
pound, after an experience with about 400 engines, working
under a great variety of conditions, are as follows.
These claims represent what this system of compound
has been designed to accomplish :
1. To compound an ordinary locomotive with the fewest possible alterations nec-
essary to obtain the greatest efficiency as a compound locomotive.
2. To develop the same amount of power on each side of the locomotive, and
avoid the racking of the machinery resulting from uneven distribution of power.
3. To make a locomotive in every respect as efficient as a single expansion engine
of similar weight and type.
4. To insure the least possible difference in the cost of repairs.
5. To attain the utmost simplicity and freedom from complication.
6. To realize the maximum economy of fuel and water.
7. To require the least possible departure from the methods of handling usual
with single expansion locomotives.
8. To permit a train, in case of break-down, to be brought in without unusual
delay, when using but one side of the locomotive.
9. To be equally applicable to passenger or freight engines.
10. To withstand the rough usage incidental to ordinary railroad service.
There are some who have had experience with this type
of compound who would not certify to the justice of these
claims, but the great majority of those who are using
these engines believe that the Baldwin Locomotive Works
have accomplished what they set out to do. It is notice-
able that the claim is made that the engines are equally
applicable for passenger and freight engines. As this is not
true of any compound in existence, and cannot be, from the
nature of things, it is not true for this type. So far as the
mechanical construction is concerned, the statement is true ;
but in the matter of efficiency, it cannot be true, for no
compound which has as much compression and wire-drawing
as this, and other types at high speeds, can ever be rela-
FOUR-CYLINDER NON-RECEIVER TANDEM TYPES. 233
tively so efficient, in comparison with single expansion
engines, in passenger, as in freight service.
123. The Johnstone System on the Mexican Central
Railway. — Figs. 129 and 130 show the construction of the
Johnstone compound cylinder. The h. p. piston is in the
centre of the annular 1. p. piston which surrounds*it. Between
the pistons there is a double barrel made of cast iron. One
of these barrels forms the h. p. cylinder ; and the other, the
outer one, forms the inner surface of the annular 1. p. piston.
The construction is clearly shown by the illustration. The
ratio of the cylinders is generally 3 to i. The valve, while
FIG. 129.
Cross-Section Through Johnstone Cylinders.
double, has but one valve stem. It is actuated by a link
motion as usual. The outer section of the valve distributes
steam to the h. p. cylinder, and the inner section to the
1. p. cylinder. The inner section is loose within the outer
section, and has a motion of about I inch independent of
the outer section, for the purpose of giving a later cut-off in
the 1. p. cylinder, and to reduce the compression in the
h. p. cylinder. The valve is cushioned from knocking by
means of two springs, one on each side of the inner valve.
The cut-off obtained by this arrangement is given in Table
U I. The starting valve used with this system is simply a
three-way cock in the cab having a small pipe leading to
the steam chest. Thirteen of these compounds are now
in operation. The only change of any importance that has
234 COMPOUND LOCOMOTIVES.
been made in the recent designs, is an increase of the steam
FIG. 130.
Arrangement of Johnstone Cylinders and Crosshead.
port which was done to reduce the wire-drawing and com-
pression.
CHAPTER XIX.
DESCRIPTION OF FOUR-CYLINDER, TWO-CRANK RECEIVER
COMPOUNDS— TANDEM RECEIVER TYPES.
124. Tandem Compounds on the Hungarian State
Railway. — The Hungarian State railways have constructed
some tandem four-cylinder receiver compounds with two
cranks with the general construction shown in Figs. 131, 132
and 133. The general description of these engines is given
in Table C C, Appendix R.
The service is that of hauling 160 tons at 50 miles an
hour on a level. This is practically passenger work ; in
fact, this engine is used in passenger traffic. Like other
receiver compounds with two cranks, the indicator cards
have the same general appearance as those taken from
two-cylinder receiver compounds. Such indicator cards as
have been given to the public were taken at slow speeds.
These give no indication of the amount of compression in
the engines at high speed. Both h. p. cylinders exhaust in
the same receiver. In starting, live steam is admitted to
the 1. p. cylinders and receiver by means of a starting valve
which is opened by the reverse lever when in full forward
gear. In this engine both valves are connected to the same
valve stem, as in the Mallet system used on the Southwest-
ern railways of Russia, 125. Likewise, as in the Mallet
and Du Bousquet, 118, systems, the piston rod stuffing-
boxes are packed separately and are accessible from the
outside as distinguished from the Brooks tandem, 127.
By connecting the two valves to one stem, it is necessary
to raise the h. p. valve seat somewhat, as is clear from
Fig. 131, but this does not give a larger clearance to the
235
236
COMPOUND LOCOMOTIVES.
h. p. cylinder than is common in compound locomotives.
In order to reduce the weight of reciprocating parts as
much as possible, the h. p. piston is forged on to the
FIG. 131.
Tandem on Hungarian State Railways — Longitudinal Section.
FIG. 132. FIG. 133.
Tandem on Hungarian State Railways — Cross Section.
piston rod, as shown in Fig. 131. The 1 . p. piston is
keyed on, as shown. The valve chest and valve seats are
FOUR-CYLINDER TANDEM TYPES.
^37
inclined, as shown in Figs, 132 and 133. In the Mallet
construction and the Brooks tandem, the 1. p. cylinder is
next to the crank, while in this engine and the tandems
used on the Northern Railways of France, the h. p. cylinder
is next to the crank. In the Hungarian type, the cylinders
are cast in one piece.
125. Tandem Compounds on the Southwestern
Railways of Russia. — In this system the 1. p. cylinder is
placed next to the crank. Both valves are connected to
the same valve stem, but are independently connected, as
shown in Fig. 134. The 1. p. piston is attached to the piston
FIG. 134.
Mallet Tandem on' Southwestern Railways of Russia — Longitudinal Section.
FIG. 135.
Piston for Mallet Tandem.
rod by screw-thread and pin, as shown in Fig. 135. The
stuffing-boxes are accessible from the outside. The clear-
COMPOUND LOCOMOTIVES.
ance in this design is considerable, as the valve seats are
unusually high. The reciprocating parts have been made
light in weight by the use of single plate pistons. The
Mallet starting gear is used, but not of the type that is
used for two-cylinder engines. This system has a simple
valve which admits steam to the 1. p. cylinder and receiver
at starting whenever the reverse lever is in full forward
gear. The construction of this engine in the cylinder part
is clearly shown in Figs. 134 and 135. The general dimen-
sions are given in Table C C, Appendix R.
FIG. 136.
Indicator Cards from Mallet Tandem on Southwestern Railways of Russia.
126. Indicator Cards from Tandem Compounds on
the Southwestern Railways of Russia. — Some indi-
cator cards taken at a comparatively slow speed are given
FOUR-CYLINDER TANDEM TYPES.
239
in Fig. 136, and the data about the card will be found in
Table E E.
TABLE EE.
Giving data for Figs. 134, 135 and 136 for Mallet Compound on South-
western Railways of Russia. Cylinders 13 in. and rq.? X 23.6 in. Drivers
79 in. diameter.
Card
Number.
Boiler
Pressure.
'.Pounds.
Revolutions
Minute.
I
162
79
2
I6I.3
120
3
165.
101
4
165.
1 68
127. The Brooks Tandem System. — Figs. 137 to 144
show the details of the tandem four-cylinder compound
recently brought out by the Brooks Locomotive Works of
Dunkirk, New York. The general dimensions of the engine
are given in Table C C. Fig. 137 shows the end view and
half section through the 1. p. cylinder, also shows the reduc-
ing valve which admits steam from the steam pipe directly
to the 1. p. cylinder at starting. Fig. 138 shows a section
through the cylinders longitudinally. The h. p. cylinder is
placed ahead of the 1. p. The 1. p. valve is of the ordinary
pattern plain slide valve. The h. p. valve is of the piston
type. These valves have an opposite motion ; that is, when
the h. p. valve goes ahead the 1. p. valve goes back. This
reversed motion is produced by means of the rocker arm
shown in Figs. 138 to 140. The h. p. steam pipe has a 2
inch vacuum valve and the 1. p. cylinder has a 2 inch relief
valve. The h. p. valve seat is made in the form of a bush-
ing shown in Figs. 141 and 142. The rock arm bearing for
reversing the motion of the valve is oiled by means of a
hole drilled through the centre of the bearing, as shown in
Fig. 140.
240
COMPOUND LOCOMOTIVES.
FOUR-CYLINDER TANDEM TYPES.
241
The exhaust steam from the front end of the h. p. cyl-
inder reaches the receiver through the centre of the h. p.
FIG. 138.
Brooks Tandem — Longitudinal Section.
FIG. 139.
Brooks Tandem — Plan of Steam Chest.
-valve, as is evident from Figs. 138 and 139. This hollow
h. p. valve has a lining of wrought iron pipe, as shown ;
the space between the pipe and the valve being filled with
;asbestos. This valve has removable ends to facilitate the
insertion of packing rings.
242
COMPOUND LOCOMOTIVES.
Figs. 143 and 144 show the starting valve arrange-
ment. This valve has a spring which keeps it closed under
normal conditions, as shown in Fig. 143, but whenever the
FIG. 140.
Brooks Tandem, Valve Rod Rocker.
TOH.P.CYL.
H.P.ST£AM
IINDUCTION
PORT.
TOH.P.CYL,
P^IG. 141. FIG. 142.
Brooks Tandem. High-Pressure Valve Bushing.
valve motion is thrown into full forward or backward gear,
the projections on the rod connected to the reverse shaft
arm force the spring down and the valve open, as shown in
Fig. 144. In this way steam is admitted to the 1. p. cyl-
• FOUR-CYLINDER TANDEM TYPES. 243
inder direct only when the reverse lever is in full forward
FIG. 143.
Brooks Tandem — Starting Valve Connections.
FIG. 144.
Brooks Tandem — Starting Valve.
or back gear. The connections for the valve and the com-
bined stuffing-box are shown in Figs. 138 and 139.
CHAPTER XX.
DESCRIPTION OF THREE AND FOUR-CRANK COMPOUNDS.
A discussion of the elementary features of these types
of compounds will be found in Appendixes I and K.
128. Webb System ; Express Locomotives without
Parallel Rods. — The general arrangement of the cylinders
and steam connections of compound locomotives of the
Webb system is illustrated by Fig. 145.- In this figure h h
FIG. 145.
Webb Three -Cylinder Compound — Cross Section Through Cylinders.
are the h. p. cylinders, which are placed so that the centres
are in a transverse line about four feet back of the front
244
THREE AND FOUR-CRANK COMPOUNDS. 245
tube sheet, and which are connected to the second pair
of driving wheels. The 1. p. cylinder / is placed beneath
the smoke box, and is connected to the forward pair of
driving wheels. The course of the steam from the boiler is
through the pipes A A to B B, and thence back to the
h. p. cylinders. The exhaust from these cylinders is led
through the pipes D D, and thence around the smoke box
through the two pipes C to the 1. p. steam chest. The
course of the exhaust from the 1. p. cylinder is clearly in-
dicated in the figure. The disposition of the cylinders and
steam pipes is essentially the same in the Webb compounds
for passenger and freight service. The most noticeable
peculiarity of the system is the absence of driving connec-
tion between the h. p. and 1. p. axles, there being no coup-
ling rods on engines having two pairs of driving wheels.
129. Webb System ; Freight Locomotives with
Parallel Rods. — In one design for freight service there are
three driving axles, the first being driven by the 1. p. cyl-
inder, and the second and third, which are coupled, being
driven by the h. p. cylinders. It will be seen that even in
this case there is no connection by coupling rods between
the h. p. and 1. p. cylinders. The principal dimensions of a
recent Webb compound locomotive are as given in Table
C C, Appendix R.
130. Webb System on Pennsylvania Railroad. — A
compound locomotive of this type was purchased by the
Pennsylvania Railroad and put into service in 1889. The
results of practical trial with the heavy trains used in the
United States were satisfactory in economy, but unsatis-
factory in hauling power. It has been found difficult to
start the ordinary weight of train with this engine, owing to
the slipping of the drivers, which were not provided with
parallel rods. When the trains are light the engine works
with the most excellent economy, and shows a decided
saving in fuel. The reports from the London & North-
246
COMPOUND LOCOMOTIVES.
western Railroad of England, where these engines have
been principally used, are very complimentary.
131. Three-Cylinder System Used on the Northern
Railways of France. — A compound locomotive having one
h. p. cylinder and two 1. p. cylinders was built by the
Northern Railway of France, and exhibited at the Paris
Exposition in 1889. The general arrangement of the cyl-
inders and steam connections of this locomotive is shown
in Fig. 146. Referring to this figure, h is the h. p. cylinder ;
/ / are the 1. p. cylinders ; A is main steam pipe to the h. p.
FIG. 146.
Three-Cylinder Compound on Northern Railways of France.
cylinder ; C C is the receiver ; and D D are the 1. p. exhaust
pipes. The 1. p. cylinders are placed as usual, and have
the valve chests above. The h. p. cylinder is placed below
the smoke box with its valve chest B below it, and is
inclined to an angle of one in ten. The locomotive is of
the Mogul type, having six coupled driving wheels, the
middle axle being the main driving axle for all three cyl-
inders. The 1. p. cranks are at right angles, and the h. p.
THREE AND FOUR-CRANK COMPOUNDS. 247
crank is midway between them, thus making an angle of
135 degrees with each 1. p. crank. It will be noticed that
the receiver is formed in the cylinder castings, and not by
pipes, as in the locomotives previously illustrated.
132. Valve Gear for Three- Cylinder Compound on
Northern Railways of France. — The h. p. valves are a
special feature of this engine. These consist of a main
valve and a cut-off valve, which slides on the back of, or
below, the main valve, the .whole forming a combination
which in principle is the same as the Meyer and Ryder cut-
offs, The edges of the cut-off valve form an oblique angle
with the axis of the cylinder, as in the Ryder valve gear,
and the ports in the main valve are correspondingly
inclined at the back of that valve, but are twisted so that
on the face next to the cylinder they are placed as is
customary. The edges of the exhaust port in the cylinder
casting are, however, inclined, and the exhaust cavity in
the main valve is formed to correspond. The yoke which
drives the main valve does not fit it at the sides, and so
permits a transverse movement while controlling it long-
itudinally. A second yoke incloses the valve, and per-
mits a longitudinal movement, but holds it transversely.
This yoke is connected to a stem, which passes through
a stuffing-box in the side of the valve chest, and is operated
from the cab by lever connections. It is clear that the
h. p. cut-off can be adjusted at any time by means of this
connection, while the valve is so proportioned that in its
extreme position the steam and exhaust ports remain open
for all positions of the h. p. piston, and steam is thus
allowed to blow through the h p. cylinder without doing
work. The engine can, therefore, be started by the 1. p.
cylinders with steam from the boiler, the h. p. piston being
then practically inoperative ; and as the 1. p. cranks are at
right angles, the starting conditions will be the same as
for a single expansion locomotive.
248 COMPOUND LOCOMOTIVES.
133. Summary of Three and Four-Crank Com-
pounds.— It has been shown by a large number of examples
that the four- cylinder two-crank types can be made
perfectly practicable in regular service and with outside
connections, and for this and other reasons it is evident
that three or four-cylinder compounds with more than two
cranks will never be generally used, and, therefore, a con-
sideration of the theoretical economies of such engines has
been omitted here. In Appendixes I and K will be found
a discussion of some features of such three-cylinder three-
crank and four-cylinder four-crank compounds as have
been built up to this time.
Such other three and four-cylinder compounds with
three or four cranks as have been designed have not been
raised to sufficient prominence to make it desirable to
discuss them here.
134 Miscellaneous Designs of Compounds that
have not been Put in Service. — Besides the designs
already shown, a great many have been proposed, such as
the Strong, Wright, Ball, Weir, and others ; but as these
engines are more or less complicated (some of them are
exceedingly complex), and have never been put into
practical operation, their consideration is omitted here for
lack of space, and also because the practical value, whether
good or bad, of such designs has not been demonstrated
by actual construction.
CHAPTER XXI
SUMMARY ABOUT STARTING GEARS,
135. Automatic Starting Gears with Intercepting-
Valves. — These gears are used solely with two-cylinder
receiver compounds, and have been described in Chapter
XV. The starting power with these gears is at a maximum
at some point during the first revolution. This maximum
point may even occur during the first quarter, and there-
after the starting power decreases until it becomes the same
as when the engine is compounded. That is, the re'ceiver
becomes so charged with exhaust steam from the h. p.
cylinder that the automatic intercepting valve opens and
the engine works compound almost immediately after start-
ing. This change may take place any time after the first
exhaust from the h. p. cylinder. If the receiver is large,
say four times the volume of the h. p, cylinder, the change
to compound may not take place until two or possibly three
exhausts have been made, but, ordinarily, it will take place
about at the end of the first half revolution. After this the
engine works compound, and with a greatly reduced hauling
power. It is clear that the larger the receiver the greater
will be the number of exhausts required to fill it, so that,
with large receivers, the period of increased starting power
will be prolonged. Such engines as have been built with
these gears have worked well in practice when they were'
well designed, except in such cases as have required a long
continued heavy pull at starting. Under these conditions,
this type of starting gear has proved inadequate. For
249
25O COMPOUND LOCOMOTIVES.
pulling long trains out of a siding, or hauling heavy loads
up a hill, or starting on a hill, or for starting heavy close-
coupled vestibule trains, this type of gear is unsatisfactory ;
but for all average work it has been shown to be quite
practicable. As might be supposed, from the development
of other features of locomotives, it is the unusual condition,
not the average, which controls, and, therefore, in starting
gears for compounds it has been found necessary to take
into account the maximum and unusual requirements rather
than the average. Perhaps it is for this reason that recent
designs of starting apparatus of this class — automatic
intercepting valves — have been given an "emergency"
feature which permits the engineer to run with a separate
exhaust for the h. p. cylinder when it is found desirable to
do so, to save time or to haul a few additional cars over a
bad place. The Richmond Locomotive Works (Mellin)
gear is an example of this kind.
From recent developments it is quite clear that there is
now a tendency, even with those who formerly favored
automatic gears, to give the engineer such apparatus as will
enable him to run non-compound when starting at slow
speeds for a sufficient time to enable him to get control of
the train. Mr. von Borries, who has been a strong advocate
of automatic starting gear of the kind that permits only one
revolution at the most before automatically changing to
compound action, has quite recently decided to use a new
arrangement, on all future compounds, which will permit the
engine to be run non-compound a sufficient length of time
to enable the engineer to get control of the train. This is
especially important by reason of the wide experience of
Mr. von "Borries with two-cylinder receiver compound loco-
motives, and from the fact that he was the original inventor
of the automatic intercepting valve.
From what is now before us, it appears that Mr. Mallet's
original plan of placing the compound and non-compound
SUMMARY ABOUT STARTING GEARS. 251
action at the will of the engineer is coming to the front for
future use. At the first introduction of compounds, railroad
men feared to give engineers control of the compound
action, and therefore favored automatic intercepting valves ;
and also it was not thought advisable to give the engineer
any more handles to turn or duties to perform than he
already had ; but now that all are more familiar with com-
pounds, and the advantages of compounding are better
appreciated, there is a general tendency to make engines
satisfactory at starting and at all other times, even with the
probability of requiring engineers to exercise better judg-
ment and to do more manual labor when starting out with
a heavy load. This seems a very logical conclusion, and
will probably lead to simpler designs hereafter, and further,
this will give a two-cylinder receiver compound that will
start trains with quite as good satisfaction as the four-
cylinder non-receiver type, and generally better than the
single expansion locomotive. Having this in mind, it is
pretty clear that the future will see less automatic and more
non-automatic starting gears for two-cylinder receiver com-
pounds.
136. Automatic Starting Gears Without Intercept-
ing Valves. — These gears, of which the Lindner is the best
known example, give practically the same maximum power
at starting as the automatic intercepting valve type, but
have the advantage of being very much simpler. In fact,
they are the simplest of all types. All that has been said
in 135 about automatic gears applies with equal force to
this type. They work well under average conditions, but
the unusual demands for hauling power are not adequately
provided for.
137. Non-Automatic Gears With Intercepting
Valves and With Separate Exhausts for the High-
Pressure Cylinders. — This type of starting gear is not
adapted to permit a separate exhaust for the h. p. cylinder
252 COMPOUND LOCOMOTIVES.
for any considerable speed, but is intended solely to pro-
vide starting power for unusually heavy demands. If used
continuously, there is a decided loss of efficiency of the
engine, and, in some designs, the fire is badly torn up by
the force of the blast. It is intended to be used with
discretion, and will give greater hauling power to the com-
pound at slow speed than is possessed by a single expansion
engine of equal rating. This greater power is given by the
larger dimensions generally used for compounds for both
h. p. and 1. p. cylinders.
138. Starting Gears for Four-Cylinder Compounds.
—When four cylinders are used, whether the engine be a
four or a two-crank locomotive, or with or without receiver,
there is practically a duplication of the cylinder power on
each side, and if steam be admitted from the boiler to the
1. p. cylinder and receiver and at the same time to the h. p.
steam chest, the locomotive will have greater starting power
than a single expansion engine of equal rating. One 1. p.
cylinder will be always ready to act with great power and
generally one h. p. cylinder will be in such a position as to
assist. Starting gears for this class of engine need no espe-
cial attention, and intercepting valves are unnecessary.
Generally a small valve is provided for admitting steam into
the receiver from the steam pipe whenever there is steam
therein after the throttle has been opened, but only when
the reverse lever is in full gear. When the reverse lever is
hooked back one notch, the valve is closed automatically.
In this way the engine can be run with increased power by
admitting steam directly into the 1. p. cylinder as long as
the reverse lever is allowed to remain in full gear. The
steam supply at this time to the 1. p. cylinder direct from the
steam pipes is but through a small pipe, and as the speed
increases the wire-drawing through this pipe increases and a
much smaller amount of steam is used in this way per stroke
after the train is moving. But it is necessary to close the
SUMMARY ABOUT STARTING GEARS. 253
direct supply valve and not permit it to be used at all times,
otherwise the economy will be seriously affected. This
has led to a demand for automatic closure when the reverse
lever is hooked up one notch.
CHAPTER XXII.
REASONS FOR ECONOMY IN COMPOUND LOCOMOTIVES.
139. Possibilities of Savings. — Compound locomotives
are considered to be more economical than single expan-
sion locomotives for all of the common reasons why com-
pound engines generally are more economical than single
expansion engines, and for some additional reasons.
The principal claims for better efficiency are based
upon :
(a) Greater expansion of steam, 45-52.
(b) Less condensation of steam due to lower range of
temperature in cylinders, 69—72.
(c) Incidental saving due to better action of the blast
on the fire, and the somewhat decreased rate of combustion
in the firebox, 83, 142-145.
Other reasons than these are frequently given ; but the
possible saving outside these features is too small to be con-
sidered at this time when locomotives are designed with so
little attention to loss of heat and are operated with such
reckless disregard of efficiency, 70, 145, 147.
The possibilities of saving by compounding are pretty
clearlv shown by indicator cards. It can be determined
within 5 per cent., from an examination of indicator cards
taken from a single expansion locomotive, what would prob-
ably be the saving from compounding, provided the design
of compound is assumed to be the best that can be devised
with the present knowledge. Many of the reported savings
from compounding have resulted from unfair comparisons in
which no allowance was made for the advantages given to
the compound, such as higher steam pressure, larger grate
254
REASONS FOR ECONOMY. 255
area, and increased heating surface. As this is now well
understood by railroad men, reported savings at the present
time are looked upon with suspicion, and this it is, perhaps,
as much as anything else, which recently led the American
Railway Master Mechanics Association to appropriate a con-
siderable sum of money to carry on a laboratory investiga-
tion of the relative merits of compound and single expansion
locomotives at the Purdue University, on the plan already
commenced by Professor Goss of that university. The
theories of economy due to compounding are so complex
and involved in their nature that mathematical investigation
is practically valueless until certain factors are definitely
determined, and it is useless to theorize much in detail
about the value of compounding locomotives until more
accurate data is at hand.
140. Saving by Greater Expansion. — In order to gain
greater expansion, the wire-drawing common in locomotives
must be greatly reduced. This demands better valve
motions and larger ports and passages, and if the possibili-
ties of gain in expansion are to be fully utilized, the steam
pressure must be considerably increased. With our present
knowledge, and our method of oiling cylinders, 200 pounds
per square inch above the atmosphere is almost the limit of
boiler pressure for good practical service, 7—19.
The saving due to compounding must very largely result
from a gain in expansion, and the more perfect use of the
higher potential of increased steam pressures. When com-
pared with a single expansion locomotive, the saving of the
compound will vary almost directly with the gain in the
useful work from a given weight of steam by greater expan-
sion, This especially applies to the substitution of com-
pounds for single expansion locomotives for use in slow
freight service on heavy grades and for suburban passenger
work. For high speed passenger work, the greater loss,
almost universal so far, in compounds, from wire-drawing
256 COMPOUND LOCOMOTIVES.
and compression, greatly reduces the saving otherwise pos-
'sible.
It may not be clear at first why the same expansion
cannot be obtained in single expansion locomotives as
in compounds, but on reflection it will be seen that ; the
mechanical difficulties with the valve motion at short cut-
offs ; the very uneven turning power applied to the drivers,
when large cylinders are used, and the enormous cylinder
condensation at short cut-offs, compel the use of compounds
for high grades of expansion. With cylinders large enough
to furnish the needed expansion, all in one cylinder, the
tendency to slipping drivers is so great as to prohibit the
-use of much expansion in a single expansion locomotive.
141. Saving by Reduction of Condensation. — To gain
the saving resulting from less condensation due to lower
range of temperature in the cylinders, better insulation of
the steam passages, steam chests and cylinders must be had,
and no great gain by saving in condensation may be
expected unless good heat insulation is provided, 69-72,
151-152.
142. Saving by more Complete Combustion. — To gain
the incidental saving due to a better action of blast, there
must be a proper arrangement of smoke box apparatus. At
the present time no one seems to know, because of lack of
accurate data, just how to arrange the smoke box mechan-
ism to get the best results. The practice on different roads
varies altogether too much to indicate any uniformity in
opinion. All know how to get a fairly good draft with a
given exhaust, and this can be done in several ways. At
the present time each new lot of locomotives is experimented
with until a sufficient blast is obtained, and there the matter
is dropped. Hence, at the present time no safe directions
can be given for the location of smoke box apparatus, and
the designer will have to be guided by the prevailing practice
on the road for which the designs are made and make such
REASONS FOR ECONOMY. 257
changes after the engine is completed as will give satisfac-
tory results. This much neglected matter is now being
investigated by the American Railway Master Mechanics
Association, 145-147. See Fig. 147.
143. Saving in Fast Express and Passenger Service.
— It is only under the best conditions that much saving can
be expected from compounds in fast passenger work. That
a practical saving is possible in this service must be admitted
by all who have studied closely the large theoretical saving
possible with compounds. Without doubt a decided saving
will be found in fast service when the valve motion receives
more attention and the steam pressure is raised to about 200
pounds above the atmosphere. In some instances a saving
in fast service has already been reported, and it is undoubt-
edly true that the reported savings were found, but whether
the economy resulted from the inferior action of the single
expansion engine with which the compound was compared,
or from the fact that the passenger service was so slow and
heavy as to give the compound somewhat the same advan-
tage that it has in freight service, is not known. Really
accurate tests of compounds in passenger service have
never been made, and ordinarily accurate tests have ojily
been made in one or two instances. See Appendixes M
and N. An average of the more reliable results obtained
shows no decided advantage for • the compound in fast
service, but this may result from the inferior action of the
steam regulating apparatus, 12-19. There is no proof,
however, that would lead to a safe conclusion that compound
locomotives of the best design now built, or when built with
the best obtainable knowledge, are not more economical than
single expansion locomotives in passenger service.
144. Saving in Slow Grade Work and in Freight
and Suburban Service. — The possible saving in slow,
heavy freight service with equally good designs and equal
advantages in all other respects for compound and single
258 COMPOUND LOCOMOTIVES.
expansion locomotives, varies from 1 5 to 50 per cent, accord-
ing to the conditions of operation. In general, the harder
the engiries are worked, the greater will be the saving from
compounding, as by it a more complete utilization of the
power of the steam will be obtained by greater expansion,
5, 1-2-19, 145.
There are special cases where incidental economies that
have not been mentioned here may be expected ; one of
these is in elevated and suburban service where it is neces-
sary to use mufflers on the exhaust of single expansion
engines. These mufflers produce a back pressure varying
from i o to 20 pounds per square inch on the pistons depend-
ing upon the condition of the mufflers. They quickly become
clogged with carbonized cylinder oil and cinder from the
smoke box and the perforations are reduced in size so much
as to require boring out frequently. With the compound a
wide open exhaust nozzle is used, as the final pressure of the
exhaust is reduced, and there is less noise than with a single
expansion engine equipped with mufflers. The saving in
fuel by reduction in back pressure probably amounts to as
much as the saving from compounding itself. Such inci-
dental savings as this and also some incidental losses, depend
upon the conditions, and an estimate of a probable saving
by the use of compounds can be made only when all of the
conditions are known, and therefore each case should be
studied by itself, 139-147.
145. How Saving is Affected by the Price of Fuel
and Rate of Combustion. — The percentage of total train
expenses that will be saved by compounding depends
largely upon the cost of fuel. If the compound is well
adapted for the work it has to do there will be some
advantages incidental to the less amount of fuel burned in
a given time ; it will be easier for the firemen, and there
will be some reduction of repairs to the engine, but
the main portion of any money saving must be expected
REASONS FOR ECONOMY.
259
from the actual saving in the fuel account. Where coal is
cheap, say from 90 cents to $1.50 per ton, the saving per
year in dollars and cents due to compounding will not be,
very great, but where coal costs from 7 to 10 dollars per ton,,
O 5O 1OO IbO 2OO
COAL USED PER SQ. FT. OF GRATE PER HOUR-LBS.
FIG. 147.
Diagram Showing the Relative Values of Different Fuels and the Increased
Boiler Efficiency with Low Rates of Combustion.
as in some of the Western States, or from 12 to 22 dollars
per ton as in Mexico and the southwestern United States,,
the money saving due to compounding is very great, and
amounts to more than the maintenance, deterioration and
interest cost for the entire locomotive equipment. This
260 COMPOUND LOCOMOTIVES.
has been the experience on the Mexican Central Railroad,
where the price of coal varies from 18 to 23 dollars per
ton. This has also been found to be true in Austria,
where coal is expensive and of inferior quality, that will
;give an evaporation of only 3^ pounds of water per pound
of coal.
Fig. 147 shows the relative value of different kinds of
coals when burned with different degrees of draft. That
is, it shows how the efficiency in water evaporation in a
locomotive boiler decreases as the coal used per square foot
of grate per hour increases. Incidentally it also shows the
difference between English and American coals and the
greater value of good fuels.
Fig. 148 shows the decrease in relative cost of fuel and
other train expenses per ton mile of cars and lading with
different prices for fuel, as the trains are increased, and will
be found useful in reaching a conclusion about the value of
a compound locomotive on any given road. A railroad
manager knows that where fuel is cheap even a large saving
in weight of fuel will but little effect the total cost of train
expenses. The ratio of the fuel expenses to total train
expenses is given by Fig. 148. It is evident from this
diagram that outside of any advantages that may accom-
pany the use of compounds, in the way of reducing repairs
and decreasing the labor of the firemen, there is but a small
percentage of total train expenses to be saved by compound-
ing when coal is about one dollar per ton ; but, on the
other hand, it is also clear that where coal costs from 15 to
20 dollars per ton, a 20 per cent, saving by compounding
very materially reduces the total train expenses.
The need of compounding is greater on some roads
than on others. Where the locomotive equipment is old-
fashioned, small and overworked, and where the boilers
have small grates, the introduction of modern heavy com-
pound locomotives with large grates frequently brings a
REASONS FOR ECONOMY.
26l
saving in total train expenses amounting to 40 per cent.
This arises from the fact that heavier trains are hauled with
the same train crew and much less fuel per ton mile is used ;
but such savings are not due to compounding alone but to
COST OF COAL PER TON-DOLLARS.
FIG. 148.
Diagram Showing the Comparative Cost of Fuel and Other Train Expenses
for Varying Prices of Fuel.
the combined effects of heavier engines, larger grates and
heating surfaces, and the saving due to compounding. Com-
pounding generally gives also some indirect advantages
which should not be overlooked, for instance it is- not pos-
sible to give to large locomotives the same relative boiler
capacity that is given to small locomotives, and the larger
and heavier the locomotive the smaller is the relative boiler
262 COMPOUND LOCOMOTIVES.
capacity that can be provided. There is a limit in the
increase of grate area at which a fireman cannot fire prop-
erly, and beyond that a further increase gives no advantage.
It is at these limits of increase of grate area and steam-
making capacity that the advantage of compounding by
reduction of total amount of fuel used in a given time is of
great benefit. At the present rate of increase of total train
loads it is quite clear that the time will soon be at hand
when compounding of locomotives will have to be resorted
to in order to reduce the demand on the boilers. See
Fig. 147.
Mr. Axel S. Vogt, Mechanical Engineer of the Pennsyl-
vania Railroad, in summing up, recently, the probable
advantages of compound locomotives for future work, has
said in effect that if the weight and speed of trains con-
tinues to increase, a limit of grate area will soon be reached,
beyond which the fire cannot be properly managed, and one
possible result of this will be to require better use of the
steam which is made. And any further increase of weight
and speed of trains will necessitate the introduction of more
improved methods of utilizing the steam, so that it appears
that the compound system will eventually be used to reduce
the demand on the boilers.
146. Cost of Repairs. — To offset the saving by the use
of compound locomotives, there is some extra cost of main-
tenance. The additional first cost will range from 100 to
500 dollars per engine, depending somewhat upon the size,
but mostly upon the design. The actual cost of the
additional parts for compounding will probably not be over
200 dollars per engine, for either the two-cylinder receiver
type or the four-cylinder non-receiver type ; when but two
cranks are used. The additional cost of three and four-
cylinder types with receivers and with three or four cranks
will be considerably greater. If the steam pressure on the
compound is higher than the single expansion engine with
REASONS FOR ECONOMY. 263
which it is compared in cost, the compound will cost some-
thing more for the stronger boiler that will be necessary,
but this addition is not large, and the total cost for com-
pounding a locomotive may, for the purpose of compari-
son, be taken at 250 dollars for the complete change.
The cost of maintenance of a compound will be greater
in the cylinders and less in the boiler. The somewhat
better and more uniform draft on the fire and the lower
rate of combustion in the firebox decreases the wear and
tear on the furnace plates and tubes. Particularly is this
true for such locomotives as have small boilers, and which
work on heavy grades, especially in those sections of the
country where fuel is cheap, for it is there that the fires are
more recklessly handled, less attention is paid to fuel econ-
omy, more fuel is burned on the grate in a given time, and
firebox failures are most frequent, particularly if the water
is bad.
In this country locomotive boiler fires are forced more
than the fires in any other type, except steam fire engine and
torpedo boat boilers, and therefore the saving of coal due
to compounding under average conditions, say 15 per cent.,
reduces the forcing of the fires so considerably that the
effect is felt at once by the fireman. A boiler that may
be difficult to fire for a single expansion locomotive may
be easily handled for a compound doing an equal amount
of work in the same time. Where the feed water contains
much sediment or scale-producing salts, the reduction in
the forcing of the boiler accompanying the use of compound
cylinders is a decided advantage, and one that makes com-
pounding worthy of consideration even where the fuel cost
is a small part of the total cost of train expenses.
The maintenance of the cylinders, pistons, crossheads,
guides, steam valves, steam chests, steam pipes and such
other parts as are connected to the cylinders, and which
are generally affected by compounding, amounts to about
264 COMPOUND LOCOMOTIVES.
3 per cent, of the total cost of locomotive repairs. The
majority of all locomotive repairs are generally those which
arise from the boiler, and a small saving in boiler repairs
will more than offset the total cylinder repairs. If the
compound system increases the cylinder repairs 100 per
cent , the total cost is small, and will be offset fully in some
cases by the consequent saving in boiler repairs. The total
cost of repairs to a locomotive is not far from 1,200 dollars
per year for large sizes. If the additional repairs to cylin-
ders, etc., due to compounding, is as much as 100 per cent,
for the parts affected, the additional cost, no allowance
being made for the saving in boiler repairs, is but 36 dollars
per year, and if there is any saving due to compounding
that is worthy of the name, it would amount in money to
more than 36 dollars in a single month, even with coal at
$1.50 per ton. See Fig. 148.
147. Methods of Operating to Gain Economy. — It
has been claimed that it is as economical to work a com-
pound engine at T6^ cut-off in the h. p. cylinder, and wire-
draw the steam through the throttle, for all grades of work
requiring less power than -f^ cut-off, as it is to cut-off
earlier in the h. p. cylinder. The fallacy of this for slow
speed compound engines with good valve gears, or for high
speed engines with adequate port and steam passages, and
a suitable valve motion, is perhaps indicated by Fig. 45,
which shows the losses due to wire-drawing in any engine,
compound or single expansion, resulting from the loss in
potential of steam pressure. It may be that in an inferior
compound, where the steam passages and valve motion and
ports are such as to give a very bad steam distribution at
high speeds and short cut-offs, it would be more eco-
nomical to use a longer cut-off and wire-draw the steam
through the throttle, certainly it has been shown that the
use of a long cut-off and a partially closed throttle gives
more power at high speed, and the highest speeds so far
REASONS FOR ECONOMY.
265
attained by compounds have only been accomplished by
this plan. But this is quite another matter, and has to do
only with power, not with economy. An engine may not be
running most economically at high speeds when it is gene-
rating the most cylinder power. So far as there is any
evidence at all in the matter, everything goes to show that
it is more economical to run with an open throttle at all
times, when the boiler is not priming, than it is to wire-
draw through the throttle. Probably the most economical
compound, all other things being equal, is one that will
BOILER PRESSURE.
FIG. 149.
Indicator Cards Showing Steam Use When the Power is Regulated by the
Throttle Lever.
run with sufficient power with a wide open throttle at cut-
offs as early as -^ of the stroke of the h. p. cylinder when
at high speed. A compound locomotive should be designed,
if possible, so that the power at all times can be regulated
by the reverse lever, and the throttle be kept wide open.
Figs. II and 12, Indicator Cards Nos. I to 14, show one
method of running compound locomotives ; namely, by
changing the point of cut-off as the speed increases. The
effect of this in the matter of wire-drawing and compression
at short cut-offs is clearly shown. Table A gives the data
for these cards. Another method, and one which some
266
COMPOUND LOCOMOTIVES.
compound locomotive builders have advised, is that shown
by Indicator Cards Nos. I to 4, Fig. 149. The data for
these cards is given in Table F F. This plan is one where
the cut-off is not made less than about -f^ of the stroke but
the power is regulated by the throttle.
TABLE F F.
Card
Boiler
Revolutions
Reverse Lever
Throttle
Number.
Pressure.
per Minute.
Notch.
opening.
I
155
144
4
H
2
1 60
228
4
H
3
1 60
246
5
X
4
150
308
5
X
When a compound engine is well proportioned for the
work it is doing, the indicator cards at average speed com-
pare favorably with those from a high speed stationary
compound engine. This is shown by Cards Nos. I to 5,
Fig. 150, which were taken from a Baldwin ten-wheel com-
pound passenger engine on the Erie Railroad. The data
regarding these cards is given in Table G G.
TABLE G G.
Card
Number.
Boiler
Pressure.
Revolutions
per minute.
Speed.
Miles an
Hour.
I
1 80
120
25.71
2
1 80
1 60
34-28
3
180
1 60
34.20
4
163
140
29.80
5
179
172
36.85
This question of the proper method of operating has two
sides to it, the economical, taking into consideration only
tlie fuel used ; from this standpoint it is better to run with a
full throttle and vary the power by changing the point of
cut-off. The other point of view takes into consideration
only the capacity of the locomotive to haul trains at high
speeds. Viewed from this last standpoint it is better with
REASONS FOR ECONOMY.
267
compound locomotives at high speed not to regulate the
power entirely by the reverse lever, but to use a rather long
cut-off and run by the throttle. A long cut-off gives larger
port openings and a later exhaust closure. This reduces the
wire-drawing through the valve and decreases the compres-
FIG, 150.
Indicator Cards From Vauclain Compound, Showing Steam Distribution at
Low Speed.
sion. Compound locomotives have more power at high
speeds when run in this way. As has been shown before,
the loss of potential of pressure by closing the throttle carries
with it a loss of efficiency that is not made up by the gain in
the saving of cylinder condensation by the superheating that
comes from wire-drawing through the throttle. See Fig. 45.
If a compound locomotive can be run entirely by the reverse
268 COMPOUND LOCOMOTIVES.
lever it is better to do so, but if the valve motion is such as
to cause excessive compression at high speed there is only
one way to get a substantial cylinder power, and that is by
using a long cut-off and wire-drawing steam through the
throttle to reduce the amount used per stroke to a point
where the boiler can keep up the supply. If both a full
throttle and a long cut-off are used at high speed, the vast
amount of steam used would quickly drain the boiler and
without a really useful result in the way of an increase of
speed ; this is for the reason that under such conditions the
increase of back pressure in the cylinders, owing to the
resistance of the exhaust nozzles, to a considerable extent
offsets the greater forward pressure on the piston.
CHAPTER XXIII.
SELECTION OF TYPE AND DETAILS OF DESIGN BEST ADAPTED
FOR A GIVEN SERVICE.
148. Four-Cylinder Four-Crank Types. — This type
has been proposed for locomotives in order to provide a
more uniform turning power on the axles, the counter-
balancing is. more perfect, and the starting power quite suf-
ficient, but such designs as have been brought out are too
complicated for practical use. See Appendix K. Crank
axles are not desirable for locomotives in this country,
although they can be made quite strong enough to with-
stand the service here. Axles should always be as simple
and plain as possible, and all bearings should be readily
accessible for American service. With crank axles the
bearings cannot be readily examined. It is of some advan-
tage also to have all of the axles of a locomotive alike so
that the stock of duplicate parts may be reduced. Crank
axles need careful watching for cracks from the day they
are forged to the time they are discarded except while in
the store-house, and their use puts an additional tax on the
motive power department, particularly so as the points
where cracks most frequently occur are not easily reached
for examination. If there was anything of real value to be
gained, either in operation or efficiency, by the use of crank
axles, undoubtedly they would be looked upon with more
favor, but so far as can be seen from actual records of ser-
vice, the plain two-crank outside- connected locomotive,
whether single expansion or compound, has all of the func-
tions necessary for the most unusual and most severe ser-
vice. Hence, as there are no theoretical advantages in
269
27O COMPOUND LOCOMOTIVES.
steam efficiency, and no advantages in practical operation
for these types that are not possessed by simpler types, they
may be dropped from further consideration, 133-134.
149. Three-Cylinder Three-Crank Types. — This type
is open to the same objections as the four-crank four-cyl-
inder type, and has the same disadvantages and is not supe-
rior to the simpler types in any particular. This type is,
however, simpler in construction than the four-cylinder
four-crank type, 128-132. All that has been said in the
preceding about the four-cylinder four-crank types applies
with equal force to the three-cylinder three-crank types, 148.
150. Four-Cylinder Tandem Two-Crank Types.—
This type is made with and without a receiver, and can be
operated by one valve for each pair of cylinders, like the
Du Bousquet (Woolf ) tandem engines on the Northern Rail-
ways of France, 118, or with two valves, as with the Mallet,
Hungarian and Brooks Locomotive Works designs, 124—127.
Only two sets of guides, crossheads, connecting rods and
link motion are necessary for this type, the same as with
the ordinary single expansion engine. So far as the theo-
retical economy or the starting power is concerned, it mat-
ters not with this type whether a receiver be or be not used,
or whether the steam be controlled with two valves, or one
for each pair of cylinders. The receiver designs give, per-
haps, the best steam distribution, and the use of two steam
valves gives better steam port openings and larger and
straighter steam passages than can be obtained with one
valve, and therefore for high speeds the receiver type with
two steam valves is better, as the steam distribution is more
readily controlled and variations can be made with less
changes in details, 73-76.
The theoretical efficiency of this type is practically
identical with that of other four-cylinder compounds, and
is nearly the same as that of the Vauclain and Johnstone
types, which are four cylinder two-crank non-tandem com-
pounds, 151.
SELECTION OF TYPE FOR A GIVEN SERVICE. 271
Those who have selected the tandem in preference to-
the non-tandem four-cylinder type, have done so with the
expectation of gaining a mechanical construction of pistons
and crossheads that is more theoretically perfect, 120, 123.
With the tandem type, the annular piston of the Johnstone
type and the uneven pressure ori the crosshead of the Vau-
clain type are avoided ; but, on the other hand, more parts
are added and the front cylinder of the tandem is placed
where it is more liable to damage in minor wrecks and col-
lisions. It makes the front truck less accessible and inter-
feres with some kinds of snow-plow and flanger attachments.
The same number of piston rod stuffing-boxes are generally
used with the tandem as with the Johnstone ; the Vauclain
has one less. The intermediate stuffing-boxes for tandems
are generally a problem difficult to solve, 127. If enough
room is taken to make them readily accessible, the over-all
dimensions of the cylinders, lengthwise of the engines is
greater than is desirable, 124-125. Hence, designers have
been led to attempt to combine the stuffing-boxes between the
h. p. and 1. p. cylinders, and special boxes of small lengthwise
dimensions have been devised. Such combined stuffing-
boxes as have been put in actual service are practically inac-.
cessible without great labor and delay, 127, so they may
be said to be impracticable, as bad leakages cannot be
readily discovered. The Mallet design of cylinders and
stuffing-boxes for tandems, 125, is probably the best that
has been put in service, but perhaps the valve rod arrange-
ment of the Hungarian tandems are better, 124. It must
be said that the tandem type has greater disadvantages than
the two-cylinder receiver type in point of mechanical con-
struction, and will probably be more inconvenient in a
railroad shop and cost more to keep in repair than the
Vauclain or Johnstone, as there are more parts to care for
and they are not so easy of access.
Those who have selected the tandem types have done
272 COMPOUND LOCOMOTIVES.
so because of some unusual conditions or some special
service. Two at least of the tandems that have been built
were made for the purpose of experiment.
151. Four-Cylinder Non-Tandem Two-Crank Types,
With and Without Receivers. — None of this type with
receivers have been built. Practically this class is repre-
sented solely by the Vauclain and Johnstone types, 120,
123. Many locomotives of the Vauclain type have been in
service, and the results of practical trials are numerous. A
number of the Johnstone type have been put into service
on the Mexican Central Railway, and so far as can be
learned no practical difficulties have been encountered.
The theoretical efficiencies of these types are identical.
The Johnstone has been used under exceptionally favorable
conditions where speeds are slow and fuel is high in price,
and a very great money saving has been gained.
The Vauclain has been used under all common con-
ditions and in some very unusual classes of services, and
the results have been correspondingly varied. In cases
where the conditions have been the same as those under
which the Johnstone has been used, the savings have been
equally great, and in other cases very unfavorable conditions
have led to little or no saving. With these compounds, as
with all others the conditions control the saving in cost of
fuel.
So far as the mechanical construction is concerned, the
Vauclain has the advantage of greater simplicity and has
parts that are more familiar to the average workman, 120-
123. The uneven pressure on the crosshead of this type,
121, led many at first to expect trouble from actual service,
but it has been pretty clearly demonstrated that so far as the
crosshead and piston construction is concerned this type
can be made to give as good service as an ordinary single
expansion engine ; but more care is required in design,
better selection must be made of piston rod material, and
SELECTION OF TYPE FOR A GIVEN SERVICE. 273
the guides must be kept well lined up to prevent as much
as possible the rocking motion that will always be induced
by this construction. The use of large diameters for the
h. p. piston rod has led to much criticism, but this has been
the result of a too rigid piston rod connection to the cross-
head. The large rods were used to remove the breakages
of piston rods at the crosshead end that were so common in
early designs. It is not believed that these large rods are
necessary ; in fact it is argued with some reason that smaller
and more flexible (perhaps longer) piston rods would be less
liable to break than the larger ones. However, the piston
rod troubles are not greater with the Vauclain type than with
the Laird crosshead type of single expansion engines at the
present time, and are not such as to cause apprehension.
So far, the Vauclain type has been used with a single
piston valve for controlling the steam in both cylinders,
120, and the results have been very satisfactory in slow
service, but it has not been shown yet that a satisfactory
steam distribution can be obtained at high piston speed with
a short cut-off (^ of the stroke). See Figs, n and 12.
The builders of this engine have advised a long cut-off (T6g-
of the stroke) and a regulation of the power by the throttle
at high piston speed, 147.
Also for the flat slide valve arrangement used with the
.Johnstone type ; it has not been shown that the steam dis-
tribution is good at high speed when the cut-off in the h. p.
cylinder is less than half stroke.
It is not as economical to use the throttle for regulation
at any speed as it is to change the point of cut-off, and prob-
ably some change in the valve dimensions ordinarily used
for these types will be needed to gain the maximum economy
for high speeds.
In extreme width laterally over the cylinders, the Vauc-
lain has the advantage, and this is an important point with
some conditions. To the practical mechanic, the Vauclain
274 COMPOUND LOCOMOTIVES.
has the simpler construction, and those who have charge of
repairing locomotives will be of the opinion that the
Vauclain has fewer parts to watch, and it is probable that
with it the piston leakage and leakage from h. p. to 1. p.
cylinder will be less in actual service. On the other hand,
the valve repairs must be less on the Johnstone, as the parts
are simpler and are of ordinary form. The Vauclain valve
bushing, 120, is not a simple detail and cannot be renewed
without considerable expense ; however, it wears but slowly
when the valves receive proper care and suitable oiling.
Of all the four-cylinder types so far built, the Vauclain
appears to be the most practical and easiest to keep in
repair, at least it has been* shown that the total additional
cost of cylinder repairs for this type is too small a factor to
be taken into account in a consideration of the value of
compounding where the cost of fuel is of any considerable
consequence.
In the past, those who have chosen the Vauclain type
have generally done so because of its greater starting power
and hauling power on inclines rather than from any
superiority in theoretical efficiency. The Baldwin Loco-
motive Works have chosen it on account of its wide appli-
cation to all classes of service. This results from the small
over-all dimensions and from the fact that it is a type of
compound that will do, under all conditions, all that a
single expansion engine will do. In point of theoretical
efficiency it is not equal to the two-cylinder type with
receiver, as it has more cooling surface and a greater
number of cylinders. In general, where other conditions
are the same, and there is the same degree of expansion of
steam, engines with the least number of cylinders will be
most economical, and there will be less cylinder condensation.
The two-cylinder receiver type, with an independent
exhaust for the h. p. cylinder at starting, is the strong com-
petitor of the Vauclain type, as it has sufficient starting
SELECTION OF TYPE FOR A GIVEN SERVICE. 275
power and somewhat better theoretical economy, and has
been shown to give better steam distribution at high speeds
with short cut-off. See Figs, n and 15. No tests have
been made that conclusively show the two -cylinder type to
be more economical, although the theory of steam use
would point that way. Yet it must not be forgotten that,
taking into consideration only those two-cylinder and
Vauclain compounds that have so far been built in this
country, the Vauclain in most* cases probably has the
advantage at low speeds and with heavy work, as the 1. p.
cylinder capacity has been made much larger and greater
expansion is had under equal conditions. With equal
1. p. cylinder capacity the two-cylinder compound will
have much greater over-all dimensions, and for large
engines this is a point of weakness in the design that
emphasizes the universal adaptability of the Vauclain type..
With a double 1. p. cylinder, as has been proposed by Mallet
(see Fig. 100), and later by Lapage (see Fig. 28), for the
nominally two-cylinder type, the needed large 1. p. cylinder
capacity can< be obtained, but this affects the theoretical!
efficiency somewhat as it gives larger cooling surfaces and!
one more cylinder. All this goes to show the need of some
accurate experiment at this time to determine the com-
parative efficiency of compounds. However, it is quite
certain that where coal is expensive or the conditions
severe a considerable saving in fuel cost will result from
the use of compounds of any type, providing the designs of
the details are correct and the proportions properly chosen*
145.
152. Two-Cylinder Two-Crank Receiver Types. —
The theoretical efficiency of this type is greater than any of
the others mentioned here. This arises from the less
number of cylinders, less cooling surface, better arrange-
ment of steam passages to prevent loss by radiation,
possibility of reheating in the receiver, 54, and the more
276 COMPOUND LOCOMOTIVES.
complete control of cut-off and compression, 73-81. In
practical service no superiority has been shown for this type
in this country, as the advantages which it possesses have
/not been utilized. To get the necessary 1. p. cylinder ca-
pacity greater over-all width has been thought to be neces-
sary, and the tendency has been to keep the cylinders, both
h. p. and 1. p., smaller than they should be This appears
from Table C C, Appendix R.
In some cases it has already been found necessary to
move the frames inward to get room for the cylinders. If
the double 1. p. cylinder be used, see Figs. 28 and 100, the
same proportion of cylinder capacity to the work to be
done can be obtained as has been used for two-cylinder
compounds in Europe, and for four-cylinder compounds in
this country.
In this type there is every chance to make a good
insulation for all of the steam passages, and there is no excuse
for placing h. p. steam on one side of a yz -inch wall and
1. p. steam, or the cooler atmosphere, on the other side, as is
generally done. This possibility of better heat insulation
has not been utilized, except in the case of the Old Colony
compound. See Figs. 72-75. The amount of re-heating in
the receiver will vary with the temperature of the smoke
box and the speed of the engine. By using a large copper
receiver with a volume not less than three times that of the
h. p. cylinder such re-heating as it is practicable to gain may
be had. As the re-heating in the receiver is done by the
waste heat in the furnace gases, all the re-heating that
takes place is clear gain, and in this way it differs from
re-heating by boiler*steam, 54.
As the cut-off in the cylinders of this type can be
readily varied there is a better chance to adjust the valves,
73-81, for the average conditions of operation than is the
case with four-cylinder engines, with one valve for two
cylinders and this more complete control of the distribution
SELECTION OF TYPE FOR A GIVEN SERVICE. 277
of steam, if taken advantage of, will give to this type
greater efficiency at high speeds.
153. In General about a Selection of a Suitable
Design. — The designer is confronted, so far as economy
is concerned, with but practically two types, viz., the two-
cylinder two-crank compounds with receiver, and the four-
cylinder two-.crank compounds with and without receiver.
To the first belong the compounds of Mallet, von Borries,
Worsdell, Lindner, Golsdorf (Austrian) , Schenectady, Rhode
Island, Dean, Brooks two-cylinder, Richmond, Chicago,
Burlington & Quincy Railroad, Pennsylvania Railroad,
Rogers, Cooke and Pittsburgh compounds. To the second
class belong the Vauclain, Johnstone, Brooks Tandem,
Mallet Tandem, Hungarian Tandem, and the Du Bousquet
types. So far as practical experience with compound loco-
motives goes, there is no evidence to show that any one
of these types has the advantage of the others in point of
economy, but there are many points of claimed advantage
for each. All that is certain is, that the four-cylinder
type is better in starting trains, and does more satisfactory
work on grades than the two-cylinder type with automatic
starting gear, but is not superior in this respect to the two
cylinder type with a separate exhaust for the h. p. cylin-
der.
The four-cylinder type will start trains satisfactorily,
and the starting gear needs but little consideration. What
needs most attention is the mechanical construction of the
driving mechanism and the arrangement of the valve motion
and steam distribution.
With the two-cylinder compound the starting power
needs first consideration. The mechanical construction is
generally good. The valve motion and steam distribution
can be readily made satisfactory by attention to the well-
known principles of designing steam ports and passages, and
the selection of a proper valve travel, and thereafter adjust-
278 COMPOUND LOCOMOTIVES.
ing the cut-offs to suit the average working of the engine.
This adjustment may be made in several ways, 73-81.
At the present time only two types of compounds have
seen sufficient service in this country to prove their practi-
cability. These are the two-cylinder two-crank receiver
types, and the four-cylinder non-tandem two-crank receiver
type, or, more concisely, the two-cylinder compound, and
the Vauclain and Johnstone compounds.
It has been shown that the two and four-cylinder two-
crank outside connected locomotives are perfectly practical
machines, so far as steam use and hauling of trains is
concerned, and therefore there is no advantage in the intro-
duction of a third or fourth crank, with the consequent
complication of parts.
It is not apparent that either the three or four-crank
types will ever come into general use, for the reason that
simplicity of design is of first importance in locomotive con-
struction, and so long as locomotives with two cranks can be
operated practically with such excellent results as at the
present time (the theoretical saving being even greater with
the two-crank than with the three or four-crank types) there
will be little chance for a general introduction of compounds
with more than two cranks. The single exception to this
statement is in the case of double-bogie locomotives, in
which there are necessarily four cranks per engine ; such
engines are in fact but two engines combined, each of which
is a two-crank compound, and all the remarks that have
been made here regarding the two-crank compounds apply
with equal force to the double bogie.
It is a pertinent fact that while the three-cylinder three-
crank compound has been given every advantage and possi-
bility of success, and every opportunity to show its practical
value, both in England on the Northwestern Railroad, and
in France on the Northern Railways, and in this country on
the Pennsylvania Railroad, yet no material advance has been
SELECTION OF TYPE FOR A GIVEN SERVICE. 279
made in the introduction of this type ; while during the
same period the use of the two-cylinder compound in
England has been largely increased, and the four-cylinder
two-crank non-receiver type has been given preference to
all other types on the Northern Railways of France.
All further consideration of locomotives having crank
shafts may be dropped, for the reason that they have no
real nor apparent theoretical or practical advantages.
The question of hauling trains in case of accident to
machinery is an important one from an operating stand-
point. Compounds with h. p. and 1. p, cylinders on the
same side can haul trains with one side disconnected. With
a separate exhaust for the h. p. cylinder and sufficient steam
supply direct to the 1. p. cylinder, the two-cylinder type
can always haul trains when only one side is disabled.
Without separate exhaust for the h. p. cylinder this type is
practically helpless in case of a broken 1. p. steam chest, or
if there is a too small steam supply to the 1. p. cylinder and
the h. p. steam chest is broken. Where the cylinders and
steam chest remain intact on both sides, this type can haul
a train at considerable speed without an exhaust from h. p.
cylinder when either side is disconnected.
So far as the details of the cylinders of compound loco-
motives are concerned, other than those that are referred to
in these pages, including heat insulation, the best that can
be done is to follow compound stationary engine practice,
making due allowance for the wide variation of power
demanded in locomotive operation, more particularly in
starting trains quickly from a period of rest, and in hauling
up short, steep inclines on otherwise level roads.
APPENDIX.
NOTE.— In the following,
v = volume of h. p. cylinders in cubic inches.
y= " " i-p.
; C= " " receiver "
R= ratio " volumes of h. p. and 1. p. cylinders.
A. Example of Calculation for Mean Effective Pressure during one Stroke, 7. —
Let the gauge pressure at the point b, Fig. i, be 145.3 pounds per square inch, so
that the absolute pressure will be 160 pounds. As cut-off takes place at one-half
stroke the ratio of expansion r = 2, and therefore the final pressure in the h. p.
cylinder will be one-half of 160 = 80 pounds. From the tables previously referred
to we find that for r — 2, p,n - .847 pi. and therefore pm = .847 x 160 = 135.5
pounds absolute pressure, which is the mean pressure between aandc measured from
the zero line of pressure.
B. Example of Calculation for Mean Effective Pressure during Expansion , 7. —
For example, the pressure at b, Fig. 3, is 160 pounds and the volume at c is twice
that at b. The ratio of expansion is therefore 2, and t>y reference to a table of
hyperbolic logarithms we find pm - 160 '—21 = 160 X .693 = 110.9 pounds between
2—1
b and c. This is for one-half of the stroke, and for the first half, from a to b, the
mean pressure is 160 pounds, therefore the average for the whole stroke would be
160 + 110.9 =
C. Example of Calculation for Pressure in the Receiver* 21. — In the present case.
Fig. i, assume the capacity of the receiver to be equal to that of the h. -p. cylinder,
or C = v, and let the pressure at e be taken at 96 pounds. At d the steam fills the
h. p. cylinder + receiver, and at e fills one-half the h. p. cylinder + receiver; there-
fore the compression is from v + C = 2 v to .5 v + C = 1.5 v, and the ratio of com-
pression is 2 v -+- 1.5 v = i. 33. The pressure at d is then 96 X .75 = 72 pounds,
and the mean pressure between e and d is 96 X .86 = 82.6 pounds. At/the volume
occupied is that of one-half the 1. p. cylinder + receiver. Assuming for the present
case that the 1. p. cylinder is 2.5 times the h. p. cylinder, or R = 2.5 the expansion
will be from 1.5 v to 2'^ v + C = 2.25 v, or the ratio of expansion is 2.25 v -+- 1.5 =
2
1.5. The pressure at f is then 96 X .67 = 64 pounds, and the mean pressure
between e and /is 96 x .81 = 77.8 pounds.
D. Final Pressure ; Total Expansion , 45-52. — In an elementary compound en-
gine, a certain fraction of the h. p. cylinder is filled with steam from the boiler at each
stroke, and after expanding in both cylinders this mass of steam finally fills the 1. p. cyl-
inder before it is exhausted into the atmosphere or condenser. For example, if the
cylinder ratio is 2.5 and the h. p. cut-off is at one-half stroke, .5 v is the volume admitted
from the boiler at each stroke, and this finally fills the volume 2.5 v before it is exhausted.
281
282 COMPOUND LOCOMOTIVES.
The steam is therefore expanded to 5 times its initial volume, or the ratio of total
expansion is 5, and the final pressure at which it is exhausted will be -i- of the
initial pressure, or 32 pounds in the case we have used for purposes of illustration.
Similarly, if the h. p. cut-off was at % stroke the ratio of total expansion would be
2.5 X | = ZJL - 6'i, and the final absolute pressure in the 1. p. cylinder would be
23Q of 160 = 24 pounds. It will be noted that the only data required in determining
the total expansion and final pressure in an elementary engine are the ratio of the
cylinders and the h. p. cut-off, or, in other words, these results are independent of
the capacity of the receiver and of the 1. p. cut-off. The effect of the size of the
receiver is seen in the shape of the indicator cards due to the compressions and expan-
sions ; but how many and how large these variations are does not affect the final
pressure. The office of the 1. p. cut-off is to control the division of the work between
the two cylinders. In a compound engine, which exhausts into the atmosphere, the
steam can, under the best and most favorable conditions, be expanded economically
until the boiler pressure is reduced to the atmospheric pressure. Steam at 160
160
pounds absolute could, therefore, be expanded = n times, nearly.
E. Drop in Pressure in Receiver, 26. — Taking f? = 2.5, C= v, h. p. cut-off at
% stroke, and 1. p. cut-off at % stroke, we have the final pressure at the end of
the expansion in the 1. p. cylinder equal to ^ of 160, or 32 pounds. The ratio
of expansion in the 1. p. cylinder is 2, therefore the pressure at the point / is
32 X 2 = 64 pounds. Then, knowing the ratio of expansion from e to /, as already
calculated to be 1.5, we have the pressure at e = 64 x 1.5 = 96 pounds, which
was assumed for the time in calculating the variations of pressure in the receiver.
Working back from this still further, we find the pressure at d as before, 72
pounds, and as the pressure at c is 80 pounds, there has been a drop in pres-
sure of 8 pounds when the h. p. exhaust opened When the 1. p. steam valve
closed at /, the pressure of the steam left in the receiver was 64 pounds. Then
when the h. p. exhaust opened, the steam which filled the h. p. cylinder at a pres-
sure of 80 pounds mixed with this, and gave a resulting pressure of 72 pounds.
To prevent drop in an elementary engine, it is only necessary to adjust the cut-off
of the 1. p. cylinder so that the volume of steam drawn by it from the receiver
equals that of the h. p. cylinder. For instance, with dimensions already given in this
paragraph, it will be evident that when the 1. p. cut-off is at — - or | of the stroke,
here will be no drop, because | of the 1. p. cylinder is equal to the whole h. p.
cylinder in volume, and if we withdraw from the receiver at each stroke a volume
which is equal to that received from the h. p. cylinder, the pressure in the receiver
will not be reduced. This can also be readily shown by calculating back from the
final pressure in the 1. p. cylinder as before. Suppose e f to represent -| of the
1. p. stroke instead of ^ , as shown in the figure, then the pressure at / would be
32 X § = 80 pounds, which would be the pressure in the receiver when the h. p.
exhaust opened; and as this is also the final pressure in the h. p. cylinder, there would
be no drop. There is, of course, always more or less drop due to wire-drawing and
friction in passages which cannot be prevented, and it must also be borne in mind
that all of these calculations are based on the assumption that pressures vary inversely
as the volumes.
F. Mean Effective Pressure; Equivalent Pressure in One Cylinder, 7. — With the
data already used the mean forward pressure in the h. p. cylinder was found to be
APPENDIX. 283
135.5 pounds. The mean receiver pressure, or h. p. back pressure, is 80.2 pounds,
and thus the mean effective pressure in the h. p. cylinder is 135.5 — 8o-2 = 55-3
pounds. For the 1. p. card, the mean pressure between e andyf was found to be 77.8
and the pressure at/was 64 pounds. The mean presssure between / and g is 64 X
.693 = 44.4 pounds. The mean forward pressure for the stroke is then TLL —
= 61.1 pounds, and assuming a back pressure of 18 pounds, or 3.3 above the atmos-
pheric pressure, the 1. p. mean effective pressure will be 61.1 — 18 = 43.1 pounds.
As the ratio between the cylinder areas is 2.5, assuming the stroke to be the same
in both cylinders, as it generally would be in practice, one pound per square inch on
the 1. p. piston is equivalent to 2.5 pounds per square inch on the h. p. piston. We
can thus readily find the effective pressure in a single cylinder, which is equivalent to
the effective pressure in the two cylinders of the compound engine. Ordinarily the
mean pressure is thus referred to the 1. p. piston, although a reference to the h. p.
piston is more convenient for some purposes. In the present case, the effective h. p.
pressure referred to the 1. p. piston is 55'3 _ 22il -phe total effective pressure referred
2-5
to the 1. p. piston is then 22.1 + 43.1 =65.2 pounds. From this we find that the propor-
tion of the total work which is done by each cylinder is, in h. p., J— = .34, and in 1. p.
65.2
43-1 scr.66. If the pressures are referred to the h. p. piston, we have 43.1 x 2.5 +
65.2
55.3 = 107.8 + 55.3 163.1 as the equivalent pressure in one cylinder of the same
size as the h. p. cylinder. Formerly common practice was to make the h. p. cylinder
of a compound locomotive of the same size as one cylinder of the single expansion
engine which it is intended to replace. On this basis the theoretical compound
engine under discussion would be developing the same work as the single expan-
sion engine when the latter was developing a mean effective pressure of % of
163.1 = 81.6 pounds in each cylinder.
G. Example of Calculation for Mean Effective Pressure when Clearance is taken
into Account, 4. — As an example of the application of the formula, let the appa-
rent cut-off be at % stroke with 8 per cent, clearance. The actual ratio of
expansion is then T * '° = 2.63, and the mean pressure between b and c will be
.33 + .08
/, 1?_Z = .594/i. This is for % of the stroke, and for the first third the mean
1.63
pressure equals /a . The mean for the stroke is therefore 2 x -594 /*i + P\ _ .73 ^.
The mean pressure calculated by formula without correction would be
H. Derivation of Formula for Tractive Force, 62. — The work done in the cylin-
ders in inch-pounds is 2 X area in square inches X mean effective pressure X twice
the stroke in inches = 2X ^ ^ d2 X ^> X 2 s. ; that at the rim of the driving wheels
is the pull in pounds X the circumference of the wheel in inches = T X 7r D; there-
fore,
2 X & if d* X p X 2 s _ d?p s.
284 COMPOUND LOCOMOTIVES.
/. Some further Discussion of Three- Cylinder Three -Crank Compounds, 129-
134. — In the three-cylinder receiver type the ratio of the volumes of the cylinders can
be made greater than "is practicable with two cylinders, and by a proper arrangement
of cranks a more uniform rotative power can be secured.
The two arrangements of three-cylinder compound engines that have been applied
to locomotives are with one h. p. and two 1. p. cylinders by the Northern Railway
of France, with two h. p. cylinders and one 1. p., the arrangement of the Webb type,
Steam Distribution, — The fundamental theory of the elementary three-cylinder
compound engines does not differ from that of two-cylinder compound engines. The
only differences which exist are the result of the relative angles of the cranks, and are
to be found in the variations in the turning moments and in the variations in pressures
in the receivers. Each case must be individually analyzed, and the only difference
between such analyses and those already given for two-cylinder engines is the greater
complication which arises from having three cranks to consider instead of two. As an
example of the method to be preferably followed in attempting such an investigation,
an arrangement of cranks which has been used for a locomotive is selected. In. this
form the low-pressure cranks are at right angles and the high-pressure crank makes
angles of 135 degrees with them. In the first place we assume the following data : In
the high-pressure cylinder, cut-off, .75; release, 90; compression, .90; in the low-
pressure cylinders the same distribution.
In Fig. 151 are shown successive positions of the three cranks, h representing the
high-pressure crank, L one low-pressure crank, and / the other. Assuming the direc-
tion of the revolution to be as indicated by the arrow, an exhaust takes place from the
high-pressure cylinder when its crank is at hl. One low-pressure crank, /j , is then just
commencing a stroke, and the other Llt has accomplished about .57 of a stroke, the
effect of the angularity of the connecting rods being neglected. From these positions
there is free communication between the three cylinders and the receiver until L
moves to L2, where the cut-off takes place in that cylinder, the other 1. p. crank being
then at /2 and the h. p. crank at hi. From these positions expansion continues in
the cylinder L, while th.er.e is still free communication between the other 1. p. cylinder,
the receiver and the h. p. cylinder until the 1. p. crank L arrives at L3, when steam is
again admitted to that cylinder for the return stroke. The other 1. p. crank is then at
/3, and the h. p. crank is at /ts. All three cylinders are now again in communication,
and remain so until the cut-off position l\ is reached, the other cranks then being at
Z,4 and /z4. The two cylinders which are represented by h and L remain in communi-
cation until the positions numbered 5 are reached, when steam is again admitted to
the cylinder /. Soon after this the h. p. exhaust takes place at h&, and a fresh supply
of steam is admitted to the receiver, from which it enters both 1. p. cylinders whose
cranks are at L6 and /6. These positions correspond to those numbered i , the direc-
tion of the piston movement only being changed. It is clear that, when the exhaust
takes place from the h. p. cylinder, the 1. p. piston corresponding to / is always near
the beginning of a stroke, while the other is near the middle of its stroke. The effects
of this distribution in the 1. p. cylinders are shown in Fig. 152 by indicator cards,
which are constructed on the assumption of rapid valve movements and neglecting
the irregularities which are caused by the connecting rods. The cards are not drawn
to a scale and the variations in pressures are purposely exaggerated. With a relatively
large receiver the drop in pressure at /a and L5 will be very small. In practice the
readmission at i would produce a hump in the card L, while the card / would have a
form which would apparently indicate that the valve was late in opening.
APPENDIX.
At earlier points of cut-off somewhat different results will be found. These are
illustrated by Figs. 153 and 154, in which it is assumed that cut-off takes place at .4
and release at .75 of the stroke in all three cylinders. Taking the direction of revolu-
tion as before, when release occurs in the h. p. cylinder at h\, one 1. p. crank is at L\
and the other is at l\ . A very slight movement brings the crank L to its cut-off posi-
tion L'i, soon after which steam is admitted to the other 1. p. cylinder at /a, and that
cylinder is in communication with the receiver and the h. p. cylinder until its cut-off
FIG. 152.
Elementary Indicator Cards from Three-Cylinder Compound.
point is reached at l\. There will then be slight compression in the h. p. cylinder and
the receiver until steam is admitted to the L cylinder at the beginning of its next
stroke. The remaining events of the revolution are similar to those already noticed
and will be made clear by a study of Fig. 153. It will be seen that there is still read-
mission to the 1. p. cylinder Z,, but that this does not effect the form of the card from
the other 1. p. cylinder. With this arrangement of cranks and with the same valve
adjustment the indicator cards from the two 1. p. cylinders will be unlike for all points
of cut-off. There is in fact but one arrangement of cranks for which the distribution
in the 1. p. cylinders will be the same, and that is when the 1. p. cranks are both at
286
COMPOUND LOCOMOTIVES.
right angles with the h. p., and therefore either directly opposite each other or par-
allel. Assuming an equal division of work between the three cylinders, the most uni-
form turning moment will be obtained by placing the cranks at angles of 120 degrees
with each other, but the difference in the distribution in the two 1. p. cylinders will
still exist.
An examination of the crank positions for the form of three-cylinder engine hav-
ing two h. p. cylinders and one 1. p. cylinder shows similar peculiarities in the distri-
FIG. 154.
Elementary Indicator Cards from Three-Cylinder Compound.
bution. This will be evident from Figs. 155 and 156, which are lettered similarly to
Figs. 151 and 153, H and h representing the two h. p. cranks, which are at right
angles, and / the 1. p. crank, which makes angles of 135 degrees with the others.
The distribution in Fig. 155 is the same as that in Fig. 151, and that in Fig. 156 is the
same as that in Fig. 153. It will be seen that there is readmission to the 1. p. cylinder
in both figures ; but at the earlier cut-off of T40- it is not probable that the effect
on a 1. p. indicator card would be noticeable. Placing the cranks at angles of 120
degrees would, as in the first arrangement of cylinders, produce very little change in
the indicator cards.
APPENDIX.
287
It is evident, from the preceding partial analysis of the steam distribution, that the
construction of theoretical indicator cards for three-cylinder compound engines will be
considerably more difficult than for the two-cylinder type, but that the same formulas
and methods of construction can be used. The remarks which were made in discuss-
ing two-cylinder compound locomotives in regard to the effect of varying the capacity
of the receiver and the results of changing the points of cut-off are equally applicable
to three-cylinder engines. In fact, the only differences are those in the steam distri-
bution, which have been already discussed, and which depend upon the angles made
by the three cranks.
A mathematical discussion of the three-cylinder type of compound engine, having
one h. p. cylinder and two 1. p. cylinders, and with the cranks placed at angles of 120
degrees with each other, will be found in the appendix to " The Marine Steam
Engine," by R. Sennett. The form having two h. p. cylinders and one 1. p. cylinder
does not appear to have been used in marine practice, and its use is not to be expected,
inasmuch as one of the chief reasons for using three cylinders instead of two is to
avoid excessively large 1. p. cylinders.
FIG. 155. F;G. 156.
Crank Circles, Three-Cylinder Compound,
-n attempting to determine the size of cylinders for three-cylinder compound loco-
motives, the best guide will undoubtedly be the results obtained with locomotives of
that lorm in practice. When such information is not obtainable, the most satisfactory
method will be that advocated under similar circumstances for two-cylinder compound
engines, i. e., the construction of, what were called for convenience, elementary indi
cator cards, and the alteration of these as experience dictates, to allow for wire-draw
ing during the opening and closing of valves, drop in pressure, etc. The proportions
which appear to have been generally adopted by Mr. Webb are, h. p. cylinders, 14
inches in diameter; 1. p. cylinder 30 inches in diameter; stroke of all pistons, 24
inches. The ratio of the volume of the 1. p. cylinder to that of both h. p. cylinders is
thus about 2. 3. Assuming a mean forward pressure of 175 pounds gauge, in the h. p.
cylinders, and a back pressure in the 1. p. cylinder of 3 pounds above the atmospheric
pressuie and an equal division of work, we can make an approximate estimate of the
maximum power of the engine as follows: The area of the 1. p. piston is 4.6 times
that oi one h. p. piston, and, if the work is to be the same in both, the mean pressure
in a h. p. cylinder must be 4.6 times that in the 1. p. cylinder. As the total range of
288 COMPOUND LOCOMOTIVES.
pressure is 172 pounds, and as the mean receiver pressure is approximately the same
as the mean h. p. back pressure and the mean 1. p. forward pressure, we have: 4.6
X 1. p. mean effective pressure = 172 — 1. p. mean effective, whence 1. p. mean effec-
tive = 172 -+- 5.6 = 30.7 pounds. The mean receiver pressure is then 30.7 + 3 = 33.7
by gauge, and the mean effective in the h. p. cylinders is 175 — 33.7 = 141.3 pounds.
A similar calculation can, of course, be made with any assumed mean forward pressure,
and this method can also be used for making an approximate comparison of the maxi-
mum work done in the cylinders of the three-cylinder compound with that in ordinary
locomotives. For example, if the mean forward pressure in the latter is 150 pounds
and the back pressure is 3 pounds as before, the total effective pressure during
a stroke will be 2 x 147 x area of one piston. To be the equivalent of the compound
locomotive this must equal 3 X 141.3 X area of one h. p. piston. This gives in the
present case 221.9 square inches as the piston area of the simple engine, or in other
words a simple engine having two cylinders about 16.8 inch in diameter, would be
equal in power, with the assumed pressures, to the compound engine having cylinders
14, 14 and 30 niches in diameter, the stroke being the same in all cylinders.
The same method can be used to find dimensions for an equivalent three-cylinder
engine having one h. p. and two 1. p. cylinders. If the ratio of the volumes of the
two 1. p. cylinders to that of the h. p. cylinder is 2.3, each 1. p. cylinder will be 1.15
times as large as the h. p. Therefore 1.15 X 1. p. mean effective pressure = 172 —
1. p. mean effective, whence 1. p. mean effective = 80 pounds. The mean receiver
pressure will be 83 pounds gauge, and the h. p. mean effective pressure will be 175 —
83 = 92 pounds. To find the piston areas we have 92 X area of the h. p. piston for
this engine = 141.3 X area of a i4~inch cylinder, which gives an area of 236.3 square
inches, 17.35 diameter, for the h. p. piston, and 1.15 times this or 271.8 square inches,
18.6 diameter, for each 1. p. piston. An engine having one h. p. cylinder 17.35 inches
in diameter and two 1. p. cylinders 18.6 inches in diameter, is thus equivalent with the
assumed pressures to one having two h. p. cylinders 14 inches in diameter and one 1.
p. cylinder 30 inches in diameter. The distribution of work among the three cylinders
is considered in what follows.
Distribution of Work. — It was shown in the theoretical discussion of the distribu-
tion of work between the cylinders of two-cylinder receiver compound locomotives,
that with the same points of cut-off in both cylinders and with the ratios of cylinder
volumes which are practicable in locomotives, considerably more than one-half of the
total work will be done by the 1. p. cylinder. It was also demonstrated that the work
can be to a great extent equalized by making the cut-off in the h. p. earlier than that
in the 1. p. cylinder.
The same process of reasoning can be applied to the three-cylinder type of com-
pound engines, inasmuch as we may regard this form as a development of the two-
cylinder type, produced by substituting either two smaller h. p. cylinders for the
original h. p. cylinder, or else two smaller 1. p. cylinders for the original single 1. p.
cylinder. It is, therefore, to be expected that, with the same points of cut-off in all
three cylinders, considerably more than one-half of the total work will be done in the
single 1. p. cylinder of the Webb type of compound locomotive, and in the two 1. p.
cylinders of the other form of three-cylinder compound locomotive which, for the
sake of brevity, may be called the French type. We may even go a step further and.
say that, with the ratios of cylinder volumes which are practicable, the total work
cannot be so divided that much less than one-half of it will be done in the 1. p.
cylinders. This statement is borne out by the published indicator cards of the Webb
locomotive and leads to some interesting conclusions.
APPENDIX.
289
These indicator cards show that the proportion of the total work which is done in
the 1. p. cylinder is from 50 to 65 per cent, at various speeds, with the 1. p. valve in
full gear. As making the 1. p. cut-off earlier would increase the proportion of work
done in that cylinder, it follows directly that thel. p. cylinder's share of the total work is
at least 50 per cent. As the Webb locomotive has no coupling rods between the h. p.
and 1. p. axles, and as the weight on each pair of drivers is very nearly the same, it is
evident that this division of work is the best under the circumstances. This point and
others can be well illustrated by a diagram of crank efforts. Such a diagram is
shown by Fig. 157, which was constructed from indicator cards of a Webb locomotive.
Steam was cut off at about ten inches in the h. p. cylinders, and the 1. p. admission
\ B Q c D AT
FIG. 157.
Diagram of Turning Moments,' Three-Cylinder Compound.
FIG. 158.
Diagram of Turning Moments, Three-Cylinder Compound.
•was at " full gear." The speed is not recorded, but from the form of the h. p>, admis-
sion line is evidently not great. The mean pressure is approximately 81 pounds in the
h. p. cylinders, and about 34 pounds in the 1. p. cylinder, which is equivalent to
34 X 2.3 = 78.2 pounds in the two h. p. cylinders, the work done in the 1. p. cylinder
thus being nearly one-half of the total.
Referring to Fig. 157, abode and/^ h k I show the variations in the turning
moments, or the tangential efforts on the cranks, of the two h. p. pistons, the cranks
being at right angles, and the irregularity caused by the connecting rods being
neglected. The combined efforts on these two cranks is shown by the curve/"/ (/ /.
The variations in the turning moments on the 1. p. crank are shown by a curve such
as B CD, and if we assume that the 1. p. crank makes angles of 135 degrees with the
h. p. cranks, this curve and that for the other stroke D E FA B will be located as
2QO
COMPOUND LOCOMOTIVES.
shown in the figure. Combining the h. p. and 1. p. diagrams gives the»full line curve
in the figure which represents the variations in the pulling power of the locomotive
during one revolution, as shown by the indicator cards, and therefore without taking
the inertia of moving parts into consideration. A comparison of this full line curve
with the curve of the combined h. p. cylinders/"/ q I shows that the angles between
the 1. p. and the two h. p. cranks are not of great importance. If the 1. p. crank were
moved back about 25 degrees, so that the maximum moment for the 1. p. crank at C
would coincide with the minimum for the combined h. p. cranks at/, the combined
diagram for all three cranks would be somewhat more uniform, but the difference
would not be great. A diagram of crank efforts on the assumption of uniform steam
pressures throughout the stroke in each cylinder shows similar peculiarities. It has
been suggested that this type of locomotive might be improved by placing the cranks
g c p
FIG. 159.
Diagram of Turning Moments, Three-Cylinder Compound.
FIG. i 60.
Diagram of Turning Moments, Three-Cylinder Compound.
at angles of 120 degrees and coupling the driving wheels. The effect of this, with the
steam distribution and division of work used in the construction of Fig. 157, is shown
by Fig. 158, in which the full line curve shows the variations in the combined rota-
tive efforts on the three cranks. It will be seen that the minimum turning moment is
greater than that in Fig. 157 and the maximum is less, so that there is a more uniform
effort throughout the revolution. The performance of the locomotive at slow speeds
would therefore be improved by this arrangement, but as the speed is increased the
inertia of the moving parts tends to diminish this apparent advantage, so that it is
doubtful if there would then be any practical gain by the introduction of coupling-
rods.
APPENDIX.
291
Turning now to the French type of three-cylinder compound locomotives, it will
be found that an application of the same method of reasoning leads to very different
results. As has been pointed out, the steam distribution is different in the two 1. p.
cylinders, but it is nevertheless to be expected that more than one-half of the total
work will be done in the 1. p. cylinders with the same points of cut-off in all three
cylinders. Also by adjusting the points of cut-off, the proportion of the total work
done in the h. p. cylinder can be decreased. It is therefore possible with this type of.
engine to divide the total work equally among the three cylinders.
— 6)r
\
.i
^° c C )•
'>> t-.
2=3 >
* 5 g:
^5 o>-
In this locomotive the two 1. p. cranks are placed at right angles, and the h. p.
crank is placed at 135 degrees with the others. A diagram of crank efforts with this,
crank arrangement and on the basis of an equal division of work, and steam admission
during about % of the stroke, is shown by Fig. 159. In this figure,- a b c <£
is the h. p. diagram, and e fg h k and m n o p q are the 1. p. diagrams. The com-
2Q2 COMPOUND LOCOMOTIVES.
bined diagram for all three cranks is shown by the full-line curve. If the cranks were
placed at angles of 120 degrees, the combined diagram would have the form shown
by the full-line curve in Fig. 160, from which it is clear that this disposition of cranks
would give a very constant turning moment.
J. Example of Modification of Elementary Indicator Cards to Approximate to
Actual Cards for Non-Receiver Compounds, 3. — An example of indicator cards con-
structed in this way is given in Fig. 161, on a much smaller scale, however, than is
advisable in practice. The assumed data in this case is as follows : Initial press-
ure, 175 pounds absolute; cylinder ratio, 3; 1. p. back-pressure, 17 pounds absolute;
cut-off in both cylinders, 0.5; release and compression in both cylinders, 0.78; volume
of h. p. clearance, 15 percent.; volume of 1. p. clearance, 6 per cent.; volume of
connecting passages, 0.3 of h. p. cylinder. The scale of pressures used in the diagram
is 80 pounds to the inch. For the benefit of those who may wish to construct such
diagrams we will follow through this case in some detail.
The following symbols will be used :
-v — volume swept by h. p. piston.
y= " " i. p.
^ = " of h. p. clearance.
C= " ofl. p.
i= " of intermediate or connecting passages.
The volumes occupied by the steam at the several lettered points on the diagram
are, then,
At b, = .5 v + c — .65 v.
At d, = .78 v + c = .93 v.
At e, = .93 v + i = 1.23 v.
At/, = v + c + I = 1.45 v.
Aig, = 1.45 v + C — 1.63 v.
At h, before cut-off, =..$v + c + i+ C + .5 V = 2.63 v.
At h, in 1. p. after cut-off, = .5 V + C = .56 V.
At h, in h. p. and passages after cut-off in 1. p., — .5 v + c +i — .95 v.
At k, before valve closure, = .22 v + c + i = .67 v.
At k, in h. p. after valve closure, = .22 v + c = .37 v.
At /, = .78 V + C= .84 V.
At n, = .22 V + C = .28V.
The pressure at d and the curve between b and d may be found by constructing
the curve through b with B as the origin, A B being .15 of A D; or by calculation as the
pressures may be taken inversely as the volumes, whence pressure at d = 175 x .65 -+-
.93 = 122.3 pounds. The drop in pressure from d to e depends upon the pressure at
k, that in turn depends upon h, and so upon g. The pressure at g depends upon that
at q and at/", and so upon e. In any case, there is but one pressure at h which will
fulfil the conditions, and that pressure must be determined by Calculation. Assuming
for the moment that we know the pressure at e to be 112.5 pounds, the pressure at/"
will be 112.5 X 1.23 -*• 1.45 = 95.4 pounds. The pressure at g is determined by the
mixture of the volume at / at 95.4 pounds with the volume of the 1. p. clearance at
pressure q. To find the latter we have pressure at q = 17 x .28 -»- .06 = 79.3 pounds.
Then pressure at g —
79.3 X .18 + 95.4 X 1.45 = ds>
.18 + 1.45
APPENDIX. 2Q3
The pressure at h — 93.7 X 1.63-1- 2-63 = 58.1 pounds. The pressure at k =
58.1 X .95 •+• .67 = 82.3 pounds. We can now find the pressure at e which is
122.3 x .93 + 82.3 x .3 = JI2>5>
•93 + -3
By combining these various expressions for pressures we can readily form a single
equation from which the pressure at h can be calculated, which is, in fact, the method
by which it was determined in this case.
Having found the pressures at e, g and h by calculation, the various curves of the
diagrams can be readily constructed. For the curve between e and f a point C is
used for the origin, which is found by laying off B C equal to .3 of A D. The curve
h k is constructed from the same origin. The compression curve k u is laid off from
B. To find the origin for tke curve g h, we proceed as follows: At g the steam
occupies the volume v + c + i + C, and at h the volume occupied is .$v + c + i + C
+ (.5l/=i.$v), The increase in volume is therefore equal to v, and therefore the
scale of this part of the diagram must be such that the horizontal distance from g to h
represents v, the volume of the h. p. cylinder. With this scale of volumes lay off D K
= .06 V — .i8v, K L = .yjt L N = v and N E = ,i$v; then E is the origin from which
to construct the curve g h. For the curves h I and n q the origin is taken at H , which
is found by laying off D H = .06 of A D, which for these curves represents the volume
of the 1. p. cylinder.
This diagram illustrates the difficulty of keeping the h. p. compression within
reasonable limits.
K. Some Further Discussion of Four-Cylinder Receiver Compounds, 124-128. —
The elementary theory of four-cylinder receiver compound locomotives is essentially
the same as that of two-cylinder receiver engines, and the four-cylinder type may be
regarded, as far as the cylinders are concerned, as formed from the two-cylinder type
by substituting for each cylinder of the latter two cylinders having a joint volume
equal to the corresponding single cylinder. It was shown in discussing two-cylinder
receiver engines that, in making approximate calculations to determine proportions,
the receiver pressure may be regarded as constant, assuming that the capacity of the
receiver is large compared with that of a h. p. cylinder. It follows from this that the
distribution of work in the cylinders is practically independent of the angle between
the h. p. and 1. p. cranks when a large receiver is used. If in a four-cylinder engine
both h. p. cylinders exhaust into one receiver, which is the reservoir from which both
1. p. cylinders are supplied with steam, the variations in pressure in this receiver
during a revolution will presumably be less than in a two-cylinder engine.
We can, therefore, in the design of four-cylinder elementary engines, make
use of formulas which are based upon a constant receiver pressure, proceeding
at first as if the engine were to have but two cylinders. The formulas are those which
are usually given for two-cylinder receiver engines, and are not of special value in the
design of two-cylinder compound locomotives on account of the necessity of a very
careful analysis of the steam distribution in that type of locomotive if the possible
advantages of compound working are to be realized.
In subsequent formulas the letters have the following meaning:
v = volume of h. p. cylinder.
V = " " 1. p. cylinder.
R = ratio of the cylinders, V= R v.
r = ratio of expansion in h. p. cylinder.
r' — ratio of expansion in 1. p. cylinder.
p\ — pressure in h. p. cylinder during admission.
2Q4 COMPOUND LOCOMOTIVES.
pi = pressure in h. p. cylinder when exhaust opens.
pz — mean measure in the receiver.
41 = pressure in 1. p. cylinder during admission.
p\ = mean 1. p, back pressure.
All pressures are absolute pressures.
Neglecting the effects of clearance, the mean foi ard pressure in the h. p.
cylinder is :
The mean effective pressure is (pm—pz) and the work done in the h. p. cylinder
during a stroke is v (pm—p*). Similarly, the mean forward pressure in the 1. p.
cylinder is,
the mean effective pressure is f/'m— /4Jand the work done in the 1. p. cylinder during
a stroke is V (p'm — -p\ ).
If the work is to be equally divided between the two cylinders, v (pm—ps)= V
(p'm—ptj.
On the basis that volumes vary inversely as the pressures, we have,
By substituting the value for/s obtained from this equation in the preceding
one, and reducing, the following is obtained:
-^(hyp. log.T- — ^) + /4= 0. (4)
By means of this equation the ratios of expansion in each cylinder (r and r' ) for
which the work done in each will be equal can be determined for any assumed values
of p\ p\ and R. If it were required that there should be no drop in pressure at the
end of the expansion in the h. p. cylinder, p% must equal ps, from which it follows
that r must equal A*. It will be found that equation (4) will give impossible values
for r' for many values of r. As r becomes less or steam is admitted to the h. p. cylin-
der during a large part of the stroke, r' will be found to be less than one which is
manifestly impossible, and shows that with a late cut-off in the h. p. cylinder the work
cannot be equally divided between the cylinders. On the other hand, as r is made
large, r' also increases until it is greater than R, which is an impracticable result, as
the receiver pressure would then be higher than the pressure in the h. p. cylinder at
the end of the expansion. For example, if we take R — 2.3,^1 = 190 pounds abso-
lute, p\ = 20 pounds absolute, and r — 1^33, or cut-off at 0.75 of the stroke in the h. p.
cylinder, the equation reduces to hyp. log. r' + .4348;- =0.3904 from which r' = 0.97.
As steam is admitted during the whole stroke when r' — i.o, it is clear that with the
above proportions more than one-half of the total work is necessarily done in the 1. p.
cylinder. If r is taken as equal to 4, with the other data the same as before, the value
of r' will be found to be 3.75, or the 1. p. cut-off would have to be placed at i -+- 3.75
or 0.267 of the stroke. But as there will be no drop in pressure between the cylinders
when r' = R, or when steam is cut-off in the 1. p. cylinder at i -t- 2.3=0.435 of the
stroke, it follows that to equalize the work in the two cylinders at the earlier cut-off the
receiver pressure would have to be higher than the pressure at the end of the
expansion in the h. p. cylinder.
The engineers of the Paris, Lyons & Mediterranean Railway have applied a for-
mula similar to the above in the determination of the proportions for a class of four-
cylinder compound locomotives, and have shown the proper relations existing between
APPENDIX.
295
the points of cut-off in the h. p. and 1. p. cylinders graphically by a diagram similar
to Fig. 162. This diagram is that given by Mr. C. Baudry, assistant engineer-in-
chief of motive power and equipment. Formulas similar to the above will be found
discussed at greater length in " Compound Engines," by Mr. Mallet. In Fig. 162 the
horizontal distances represent the points of cut-off in the h. p. cylinder, and the verti-
cal distances represent the points of cut-off in the 1. p. cylinder. The inclined lines
.are curves which represent the solution of equation (4) for different values of K, the
pressures used in the construction of the diagram probably being 213 and 21 pounds.
For example, if R — 2.5 when the h. p. cut-off is at 0.4, the 1. p. cut-off should be at
about 0.5 in order to equalize the work. If the ratio R — 2, a cut-off at 0.4 in the
h. p. requires a cut-off at about 0.58 in the 1. p. cylinder. For the cases in which the
equation gives values of r' which are too small, the cut-off for the 1. p. cylinder is fixed
0.80
/ /c /
0.70
0.80
FIG. 162.
Diagram Showing the Ratios of Cut-off in High and Low-Pressure
Cylinders of Four-Cylinder Compound.
at 0.8 or the maximum for full gear. For instance, taking R = 2, the 1. p. cut-off
would remain at 0.8, or full gear for all values of the h. p. cut-off greater than 0.58,
although more than one-half of the work would be done in the 1. p. cylinder. The
other limit to the application of the formula is fixed by making the earliest 1. p. cut-
off that at which there will be no drop in pressure between the cylinders. So that
finally, the relation between the points of cut-off in the two cylinders is shown by
broken lines such as a b c d, for which R — 1.82. For example, if R = 2, the diagram
shows that the points of cut-off should vary as follows :
High- pressure 10 .20 -30 .40 .50 ,60 .70 .80
Low-pressure 50 .50 .50 .58 .70 .80 .80 .80
Three experimental types have been constructed by the Paris, Lyons & Mediter-
ranean Railway. Fig. 163 shows the general arrangement of the compound locomo-
tives intended for fast passenger service. The principal dimensions of these locomo-
tives, and of the type of simple locomotive which formed the basis for the design, are
given in Table JJ. The table shows that two compound locomotives of this and of
each of the succeeding types have been built, which differ only in the number and
diameter of the tubes. It will be seen that in the type of locomotive illustrated by Fig.
163 all four cylinders are placed beneath the smoke box, with their axes horizontal.
296
COMPOUND LOCOMOTIVES.
The two h. p. cylinders are between the frames and are connected to the lorward
driving axle. The 1. p cylinders are connected to the rear driving axle. The axles
are so coupled that the h. p. crank on each side leads the 1. p. crank *bn the same side
o:
T
l
i
fcl
o
198°. The object of this arrangement is to obtain as large a value for the minimum
starting power as possible. In Fig. 164 is shown the general arrangement of the four-
cylinder compound locomotives for freight service. In this locomotive the second
driving axle is connected to the 1. p. cylinders, and the third axle to the h. p. cylinders.
The h. p. crank on each side leads the 1. p. crank 232° 48'. In the corresponding-
APPENDIX.
297
simple locomotive, of which the dimensions are given in the sixth column of the table,
the rear axle is not a driving axle. Fig. 165 illustrates the arrangement adopted for
locomotives for steep grades. The h. p. cylinders are connected to the second axle,
U-r
and the 1. p. cylinders to the third axle. The h. p. cranks lead the adjacent 1. p.
cranks, as in the other designs, but in this case the angle is 235° 54'.
The Walschaert valve gear is used for all of these locomotives, and the points of
cut-off in the h. p. and 1. p. cylinders are adjusted by means of a complicated cam
arrangement, designed to fulfill the requirements indicated by Fig. 162. The starting
2Q8
COMPOUND LOCOMOTIVES.
gear adopted for these locomotives consists of simply an auxiliary steam pipe and
cock for admitting steam from the boiler to the receiver, which is fitted with a safety
valve as usual.
For the express locomotive, Fig. 163, in which the question of the balancing of the
reciprocating parts at high speeds would be of most importance, the angle selected,
V
"N'ON In M" 0 m E 0*
c>fn»ri fco H TI-VO o o •*
1
c/5
"B*« °«SS>*
(M "HOM""" Q Q ' • *
N IN PI IN
VO
H
.&"
1
1
S
N«JJ>OIO H d ON ir> t^.
_ 2 ^ ^ . ^
MM X\ Q\ . . .
H ino oo oo N M f^
J
w
JlfxHfu
t^ ONVO ON _ ON in « Tj- M M
^ w" ^ J? M~ ^^
V
w *no oo H c ^O m
S:?m rOMON^OOO M
E
53
W H m o "^ H o -^-vO Tf
g M vo N O;^H in ro ON M^ q^ . . W_
W M H S 11 ' ' "
H
vo"
US^ vo1 2" O"O-MO"
t^^^OO 00
.5?
E
T:
§
J
• i*m «fe»*
H in^o + ¥ w 4m
OO ONX O O -^- in m
a
PM
a
3^JS||
"5,
E
53
vo •*o oo fj q <N q ro
M K VO H ' ' "
E
c
3
o
PM
?N" >r>H ^^^^^
^_^ * t*. « M vq «>.
PJ
W -^- O m »H o U*N.OO co
^(yS:«Ht^?«~vo>H'
°
w
MM tx w
" H^2
c •
g •
V • •
::::*! :"« : .§'§
: : : : : 8 : :
::«::« : *| ° d-
ii!li}i'iili
Plllll1!-1
Illllllllll
: :^ : :.c : ^g ^on
JUslSs 118, *S.
I^Se-58. J?-3\S^
^7gSjl .rgS'ScS
lBgi'&3*i8!^;&
l-s^«^p|||^|«
°JJ Bll-9 8 *** rf *
fs*fi.ajsl^^Es
I!illl1pii2.lf
e|iiir=^La§I
»- K ox M OJD w *>""""*M««- S.
ll-fifff go|££^^*
E | £?«s « | s l-^tS-gja
3 .2 g w v v .2 SJ .2 « <u « « -3
^CjffiKffiQ<C^^«f2(^
APPENDIX.
299
198° , is approximately half way between 180° and 225°. For the freight locomotive
the starting power was apparently given greater weight in the problem , the angles in
each design being 225° plus the angle of inclination of the h. p. cylinders
f Admisson of the Auxiliary
Steam by the Low Pressure Slide
$V\de 4
For the phrases HI, IT, and VH, via
The lines marked 6' represent the
Steam as led from the regulator, The
lines marked /.• 2 represent the Steam
as led from the Main Steam Pipe .
Commencement of Admisson of the Auzilia
Steam by the Low Pressure Slide .
Diagram of Turning Moment at Driving Axle
Compound Locomotive, Lindner System.
FIG. 166.
L. Diagram of Turning Moments of a Lindner Two-Cylinder Receiver Compound,
103-107. — Fig. 166 shows an interesting diagram devised by Lindner to* explain the
turning moment of the Lindner compound at the driving axle. It applies to a Lind-
nei express engine in which the h. p. crank leads. The boiler pressure is 180 pounds
by gauge. The cylinder ratio is 2 2.
The path of the crank and the periphery a of the wheel are shown on a scale of
•gV natural size, and the tangential forces transmitted to the periphery of the wheel are
shown as lines b extending outward from the circumference, each millimeter of their
departure from a representing one kilogram.
The adhesion circle c corresponds to a tractive force of 4,000 kilograms equal ?
of the adhesion weight, while the mean tractive force calculated from the dimension?
3OO COMPOUND LOCOMOTIVES.
of the locomotive according to the formula z = °'^ X ! E (which is the formula for
compound locomotives) is given at 3,700 kilograms, d and / representing the diameter
and stroke respectively of the h. p. cylinder, p the boiler pressure, and D the diameter
of the driving wheel.
For the conditions of starting with various positions of crank, four phases or
periods must be considered for each semi-circle.
(1) Phases II-III and VI-VII:
Within these phases the impulse takes place with increasing force from the h. p.
piston alone without any back pressure, and as in every ordinary locomotive.
(2) Phases IV-V and VIII-I:
The impulse takes place with a force which increases within these phases, and is
produced by the 1. p. cylinder alone, with at least the same force as in phases II-III
and VI-VII, while the h. p. piston is at the same time relieved by the small equalizing
channels in the high-pressure slide,
(3) Phases I-II and V-VI :
The impulse is derived mainly from the 1. p. piston acting with a great force,
which, however, diminishes within the phases, while the h. p. piston acts with small
but increasing force, and the motive effect of these two forces are combined
(4) Phases III-IV and VII-VIII:
The impulse, where the auxiliary steam is led from the regulator, is derived solely
from the h. p. piston with a great force, which diminishes somewhat within the phases,
as represented by the pressure line b I.
Where the auxiliary steam is led from the main steam pipe, the 1. p. piston also
works simultaneously with small but increasing force. The pressure which is then
developed on the 1. p. piston acts back upon the h. p. piston; but, since the h. p.
crank is in the most favorable position, the impulse is speedily given by the h. p. pis-
ton, and the motive effect does not in any case fall below the minimum values at
the commencement of the phases indicated by (i) and (2) where only one piston is
.^working at a time, but will correspond with the pressure line.
APPENDIX.
301
M. Some Tests of Compound Locomotives in the United States.
TABLE II.
Giving List of some Tests of Compound Locomotives which have been made in the
United States, and References.
Type of
Compound.
Where Tested.
Reference.
Compara-
tive Value
of Test.
Baltimore & Ohio R.R.
Mexican Central Ry.
Pennsylvania R.R
Lehigh Valley R.R
Mexican Central Ry..
Lehigh Valley R.R.
Mexican Central Ry. .
Mexican Central Ry .
Mexican National Ry.
Mexican Central Ry
West. Maryland R.R.
Old Colony R.R
Illinois Central R.R.
C., M. & St. P
C.,M. & St. P
Mexican Central Ry
Old Colony R.R
M. K. & T. R.R. .
E. Tenn., Virg. & Ga.
Cin., N. O.&Tex.Pac.
N. Y., Chic. & St. L..
C., B. & Q
C., B. & Q
C., B. & Q
Old Colony R.R
West. N. Y. & Penn.
E. Tenn., Virg. & Ga.
E. Tenn., Virg. & Ga.
Union Elev., Brooklyn
Union Elev., Brooklyn
Union Elev., Brooklyn
Southern Pacific
R. R
Ry.
Evg.
. G., il
i!
it
if
Reviev
News,
go — Pages 627, 634, 651, 668, 711
*9i ' 35°, 352, 354
' 363
' ' 161
Fair
Unimpr't.
Fair
Unimpr't.
Fair
Unimpr't.
Fair
Unimpr't.
Fair
Johnstone
Vauclain
Johnstone
Vauclain & Dean
Johnstone
Johnstone
Vauclain
Johnstone
Vauclain
Dean
Vauclain
Vauclain
Vauclain
Johnstone
Dean
373
655
' 775
' 812
' 858
92 113
IQ5
' 384
442, 443, 444
471,472-5, 488, 490-94
577, 583-4
' " 708
Vauclain
Pitkin
Vauclain
Vauclain . .
Lindner
Lindner
Vauclain
Dean
Vauclain
Pitkin
Pitkin
Rhode Island. . .
Rhode Island. . .
Rhode Island. .
Pitkin
" 838
' " 987
93 " 162, 163, 170
" 312
202-6, 211, 273
3!3» 3*4, 335-7-8
' " 273, 462
f, 1891 " 657 ....
Nov. 1890, Pages 458
Dec 1891, ' 545-6
^1891, " 6-10
" 556-7
Feb. " " 193
Jun. 1892, " 588
Jun. " " 636-9,646-8,657
Jul. ; 6
Vauclain
Vauclain
Vauclain
Central R.R. of N. J . .
C., M.&St. P
C.,M.&St. P
302
31
'« a
^ E
8 £
II
. ^ a
h- ' s -2
ffi § ^
ffi -S.-M
I!
I?
<^ — •
« %
5 K
^ c
COMPOUND LOCOMOTIVES.
Some Reported Savings by Compounds in the United States :
!~JSB I O . ~ — •• - — -
|1| 8 J
agF&l
NNNWNfOC<C1IC4fOrOWrOH'^"(r>WrONrrjWW 1-1 N w N M w M C^NWH
:H ::::: :H ::
'''''' '''' '' « : ''*
s
•SI'
'i cj u u '
D aj • • * • *a »-i • D *
c c^c ; l.g ^ a e.g.g.g.S.S.g : : ".E.5.5.5.S.S :.5^.£ C.£.S.S ".S • -.£
' y ^ E| s B r««« SSScgcgJ ^ g£!.s-p j> s* s
o g« |SJjA^ajM &&^?<««^« 1 >«S |£|3|^
APPENDIX. 303
O. Formulas for Expansion Curve. — The formula for the rectangular hyper-
bola is
p • y= c
in which P is the absolute pressure at any point of the stroke, V the total volume
occupied by the steam, and C a constant number depending upon the pressure and
volume at cut-off, or at any point in the stroke that is used as the basis for com-
parison. To find C' take the volume occupied by the steam at any point of the stroke
and multiply it by the absolute steam pressure at that point. To find the pressure at
any point in the stroke divide C' by the total volume at that point.
The formula for the adiabatic expansion curve is approximately
P. v.v = c-
In this formula the letters have the same signification as given above, and the value of
C ' is found in the same way. To find the pressure at any point divide C ' by the total
volume at that point raised to V power. The powers and roots are best obtained by
means of logarithms. To find the loth power, take the logarithm of the number and
multiply it by 10, then find the number corresponding to this product in the logarith-
mic table. To extract the gth root of a number, take the logarithm of the number and
divide by 9, and find the number in the logarithmic table corresponding to the quo-
tient. The adiabatic curve of expansion is one that takes into consideration the
amount of steam condensed in doing useful work in the cylinders, as distinguished
from that condensed by the cooling effect of the cylinder walls. The hyperbola does
not allow for condensation, but simply assumes an expansion where the pressure
varies inversely as the volume occupied by the steam; that is, when the volume is
made twice, three or four times as large, the pressures would be %, %, and %
respectively.
The saturation curve or curve of equal steam weight can be plotted directly from
a steam table, which gives the volume of an equal weight of steam at different abso-
lute pressures.
The curve of equal total heat can be plotted from a steam table which gives the
total heat of an equal weight of steam at different absolute pressures.
P. Formula for Inertia of Reciprocating Parts. — Especially in high speed
engines the inertia of the reciprocating parts materially alters the distribution of the
pressure on the crank pin during the stroke, although the mean effective pressure as
shown by the indicator card for each stroke is not changed. The only effect of the
inertia of reciprocating parts is to reduce the pressure on the crank pin during the
first part of the stroke and increase it during the last part of the stroke. During the
first half of the stroke the velocity of the reciprocating parts is increased, and during
the last half the velocity is decreased. In the beginning of the stroke a portion of the
power of the steam is used to accelerate the reciprocating parts, and in the latter part
of the stroke the pressure on the crank pin is increased by the force required to retard
the reciprocating parts.
The simple formula for the inertia of the reciprocating parts at any angle of the
crank a is :
.ojiwy- Cosine a>
This formula does not take into account the obliquity of the connecting rod, but
it is quite near enough for ordinary analysis to omit this factor, particularly where the
connecting rod has considerable length in proportion to the stroke. The shorter the
304 COMPOUND LOCOMOTIVES.
connecting rod the more necessary it is to include the obliquity of the rod and the
formula for such cases can be found in technical books on steam engines.
In the foregoing formula W is the weight in pounds of the piston, piston rod,
crosshead and part of the connecting rod. The portion of the connecting rod to be
taken varies with the design. For all ordinary analyses take 1A of the weight of the rod.
R - radius of crank in feet.
V '= equals the velocity of the crank pin in its circular path around the axle. This
velocity may be found by multiplying the velocity of the train in feet per seconds by
the stroke of the cylinders and dividing by the diameter of the drivers.
a is the angle of the crank with the horizontal line through the wheel centres at
the point where it is desired to find the inertia of reciprocating parts. The cosine of
the angle may be found from any book giving a table of natural sines and cosines as
distinguished from the logarithmic sines and cosines.
The inertia of the reciprocating parts is to be subtracted from the total steam
pressure on the piston for the first half of the stroke and added to the total steam
pressure on the piston for the last half of the stroke in order to find the actual pressure
on the crank pin.
The following is an example of the application of this formula :
The weight of reciprocating parts 600 pounds — W.
Velocity of train 60 miles an hour or 88 feet per second
Diameter of drivers 6 feet.
Stroke of piston 2 feet.
Total piston pressure 38170 pounds.
Angle of crank with horizontal line through centres of drivers =35°= &•
Position of crank = first half of stroke.
Cosine of 35°= .819.
Velocity of crank pin in circular path = 2 = 29.3 = V
6
The square of 29.3 is 858. = V12
The inertia of the reciprocating parts at an angle of 35° is
•°3IX600X858-X. 819 =12988 pounds.
The actual pressure on the crank pin, when the crank has moved 35 degrees
from the end of the stroke, is the difference between the total steam pressure and the
inertia of the reciprocating parts, or —
38170—12988=25182 pounds.
APPENDIX.
305
Q. TABLE L.
Comparative Cylinder Capacities of Compound Locomotives.
i*o «j jj
. ai
. in
4>
E
£
"3 *j t> 3
%
||
l|
1
O «
•c
n .
Jtsll
S
By whom Operated
or Built.
Type of
Engine.
lu-
L
?
11
e«
°s
-•-M
W
s
Remarks.
ll
35
rt .5
1
1 Diameti
JS
tkO
1
o|£g
'§
fa
Saxon State R. R.
Lindner
25.6
18.1
24
55-6
29.0
58.8
Frgt.
2 Cylinder.
44 44 44
44
23.6
16.5
22.1
75
32.0
30.8
Exp.
2 "
44 44 44
"
25.6
16.5
22.1
75
32.0
36.2
"
2 "
C. B. & Q.
"
29
20
24
68
45-8
38.8
"
2 "
Vladikavkaz
"
28
19^8
25^
47 Y*
49.9
50.8
Frgt}
2 "
Pennsylvania R. R.
"
31
19-5
28
84
42.0
46.1
Exp.
2 "
Michigan Central R. R.
Schenec-
tady
29
12
24
68
48.5
36.8
"
10 Wheel 2 Cyl.
44 44 44
*4
29
20
24
74
49-5
32.8
"
10 " "
Southern Pacific
44
28
2O
26
55
49-8
44.6
Frgt.
JO " "
"
29
20
24
69
48-3
36-5
Exp.
10 " "
Adirondack & St.Lawrn'e
"
30
2O
26
57
57 3
Frgt.
Mogul "
44 44 44
"
30
20
26
70
54-o
37-3
Exp.
10 Wheel
Pennsylvania R. R.
"
30
20
24
74
53 o
33-2
"
10 " "
East Tenn. Va. & Ga.
"
29
20
24
Si
57-8
41.1
Frgt.
Consol. Cyl.
Brooklyn "L"
Rhode
Island
18
"J*
16
42
15-8
46.8
Pass.
Forney Cyl.
N. Y., N. H. & H. R. R.
28
18
24
78
33-3
43-6
Exp.
8 Wheel Cyl.
Minneapolis & St. Louis
"
28
19
24
68
33-5
49-7
"
8 " ft
Northern Adirondack
"
28
19
26
62
46.4
42.8
"
10 " "
Fitchburg
"
31
21
26
63
54-0
44.2
Frgt.
Mogul "
M. St. P. & Ste. Marie.
<f
31
21
24
So
59-i
47.0
6t
Consol. Cyl.
N. Y.,N. H. & H. R. R.
"
31
21
26
78
42.0
46.1
Exp.
8 Wheel
Chicago M. & St. Paul
"
31
21
26
78
45-°
43-o
44 .
10 " "
Grafton & Upton
Lake Street Elevated
"
28
21
18
13
24
18
55
44
43-o
21 .O
47-8
51.8
Frgt.
Pass.
Mogul Forney 2"
8 Wheel Cyl.
Northeast England
Worsdell
28
20
24
91^
l8.5
66.6
Exp.
2 Drivers, Cyl.
Old Colony R. R.
Dean
28
20
24
69
33-2
49.0
"
8 Wheel
Lehigh Valley R. R.
C & S S. R. T. R. R.
Baldwin
Brooks
30
2O
28^
20
14
18
24
16
24
So
42
56
28.7
20.0
38.3
90.8
45-9
52.6
Frgt.
Pass.
Frgt.
Consol.
Forney '
10 Wheel
Lake Shore & Mich. So.
Cooke
27
jq
24
64
48.5
34-o
(C
10 4< '
Jura-Simplon
Mallet
26.4
17.7
25.6
72
30.6
48.8
Exp.
American '
!!
Pittsburgh
Richmond
29
29
19
26
72
54
47-5
Si-5
Frgt.
8 Wheel '
Mogul "
Chesapeake & Ohio
C. C. C. & St. L.
29
3°
19
24
24
57
56
«
10 Wheel "
10 "
Illinois Central R. R.
Rogers
29
20
26
56
53-7
43-8
"
Mogul "
West India Imp. Co.
ft
29
20
26
50
48.5
54-3
"
10 Wheel
Jura, Berne -Lucerne
von
Borries
25-5
I8.5
26
59
Exp.
8 " 2 "
Pennsylvania R. R.
Webb
30
14
24
75
33-4
51-6
**
3 Cylinder.
London & N. W.
Chemnitz, Eng. Works
Lindner
3°
15
24
21
85
43^
34-7
44.0
60.6
Frgt.
8 Wheel 3 Cyl.
4 Cylinder.
Baltimore & Ohio
Vauclain
20
12
24
66
37-8
46.0
'*
8 Wheel 4 Cyl.
Northern Pacific
"
19
II
24
56
45-o
41.2
"
Consol. 4 "
Bahia Exten. Brazil
New South Wales
West. N. Y. & Penn.
;;
IS
22
21
13
18
26
26
37
51
26.5
61.5
58-2
49.6
48.0
47-2
Exp.
Frgt.
4 Cylinder.
10 Wheel 4Cvl.
10 4 "
C. & S. S. R. T. R. R.
44
15
9
16
42
20.0
51-8
Exp.
Forney 4 "
Cent. R. R. of Georgia
'
19
24
68
3O.O
51-
"
8 Wheel 4 "
Cen. R. R. of New Jersey
Columbian Exposition
4
22
22
13
13
24
26
78
84%
44.2
41.6
40.4
43-4
"
8 " 4 "
4 "
44 44
*
24
J4
24
72
46.8
49.6
'*
10 Wheel 4 "
Missouri, Kansas & Texas
«
24
i4
26
56
67.0
48.0
Frgt.
Consol. 4 "
N. Y. L. E. & W.
Paris, Lyons & Med.
4 Cylinder
27
19.7
16
12.2
28
24.4
5°
78.7
85-0
32-5
58.0
44-4
Exp.
Decapod 4 "
306
COMPOUND LOCOMOTIVES.
TABLE L.— Continued.
i'o }5 g
•8
dj
(I
y
jO
Ilia
•A
,C
r£
>
>
2-2 -u<c
Si
By whom Operated
or Built.
Type of
Engine.
~ C
o1"1
£ c
meter of h
nder. Inc
(J5
"o
.C
Q ^
Q M-
of 1. p. pis
nent per
per ton on
nparative
>ht or Exp
Remarks.
55
•J
i
.%
Q-
1
1§1§
•3"S.i:<
I
Paris, Lyons & Med.
4 Cylinder
21.3
i3-4
25.6
59 o
62.5
38-0
Frgt.
" " "
4 "
21.3
14.2
25-6
49-5
63.0
44-4
"
Decauville
Mallet
articulated
II. O
7-4
10.2
23.6
12.9
48.4
"
4 Cylinder.
4
Herault
18,1
12. I
20-5
47-2
38-5
44 -o
«<
4 "
Central Suisse
"
21.7
14.0
25.2
65.0
40.0
"
4
Gothard
Alsatian Constructors
No. R. R. of France
Woolf
22.8
20.9
26.0
15-8
13-4
15-0
25.2
25 2
25.6
48^4
83.2
51.2
93-7
33-6
56-9
34-4
47.6
71.2
Exp.
Frgt.
8 Wheel 4 Cyl.
Tandem 4 Cyl,
Great Northern
Brooks
22.0 1^.0
26
55-°
65.0
42.6
Consol.
So. W. Russia
Mallet
19.7
13.0
23.6
79.0
93-7
70.9
Exp.
Hungarian State
Woolf
19.2
13.6
26
78.5
30.8
48.0
"
Mexican Central
Johnstone
24 K
3toi
3toi
14.0
14.0
24
24
48.0
56-0
50.0
52-5
70.4
57-6
Frgt.
Annular Cyls.
Annular Cyls.
4 Cyls.
" Northern
Mex. Cuernavaca & Pac.
24 l/4
14.0
14.0
24
24
56-0
56.0
5i-5
59-2
59-2
„
4 Cylinders
4
Mexican Central
22^
13-0
24
48.0
50.0
61.0
"
4
" "
22^
13.0
24
56.0
38.0
68.8
Exp.
4
"
22^
22^
13-0
13.0
24
24
48.0
48.0
50.0
105.0
61.0
58.4
Frgt.
Double Bogie.
APPENDIX.
307
R. TABLE C C.
Dimensions of some of the more Prominent Compound Locomotives that have
been put into Actual Service, Chiefly in the United States.
Buifafer.
Patentee.
•Bid
&as
£J^
Railroad Company.
Baldwin Locomotive Works
Neustadt Locomotive Works
Northern R'y of France
Brooks' Locomotive Works
Chicago Burlington & Quincy
Chemnitz Engine Works
Pennsylvania R. R. Shops
Cooke Locomotive Works
Kolomna Engine Works (Moscow)
Old Colony R. R.
Lehigh Valley R. R.
Alsatian Constructors
J. A. Maffie, Munich
S.M. Vauclain
4Cyl.
4
4
4
4
4
4
2
2
3
2
Tandem
2 Cyl.
2 "
2 "
2 "
2 "
2 "
Tandem
4 Cyl.
4 "
2 "
Tandem
2 Cyl.
2 "
2 "
4 "
4 "
4 '
4 '
4 '
3 "
3 "
3 "
3 '
3 '
3 '
3 '
2 '
2 '
2 '
2 "
C. & S. S. R. T. R. R.
Central R. R. of Ga.
Central R. R. of N. J.
Columbian Exposition
Missouri, Kan. & Tex.
N.Y..L. E. & W.
C. & S. S. R. T. R. R.
Nothrn Ry of Austria.
<' " " France.
Lake S. & Mich. So.
Great Northern.
C., B. & Q.
Royal Saxon State.
Pennsylvania R. R.
Experimental.
St. Petersb. & Warsaw.
Old Colony.
Lehigh Valley.
South West Russia.
St. Gothard.
Central Suisse.
Jura Simplon
So. R. R. of France.
Hungarian State.
North Eastern.
Chesapeake & Ohio.
C. C. C. & St. L.
Mexican Central.
" Northern.
M. Cuernavaca & Pac.
Mexican Central.
Brooklyn Union "L."
N. Y., N. H. & H.
C. Golsdorf
J. Player
A. Lindner
' von Borries
F.4W. Dean
A. Mallet
Alsatian Constructors
Hungarian Ry. Shops, Buda-Pesth
So. Eastern Ry, Gateshead Shops
Richmond Locomotive Works
Rhode Island Locomotive Works
Mexican Central R. R.
Rogers Locomotive Works
Schenectady Locomotive Works
London & North Western
Hanover Machine Works
T. W. Worsdell
C. J. Mellin
F. W. Johnstone
C. H. Batchellor
« c«
« «
F.( W. Johnstone
Minneap's & St.Louis.
Northern Adirondack.
Fitchburg.
M. St. P. S. St. M.
N. Y., N. H. & H.
C. M. & St. P.
Grafton & Upton.
Lake St. "L." Chicago
Mexican Central.
Illinois Central.
West India Imp. Co.
Southern Pacific.
Adirondack & St. L.
Pennsylvania.
E. Tenn., Va. & Ga.
Michigan Central.
London & N. W.
Prussian State,
jrand Trunk. >
Bengal & Nagpur, Ind.
Jura, Berne- Lucerne.
A. J. Pitkin
F. W. Webb
A. v n Borries
Worsdell & von Borries
A. von Borries
Neilson & Co., Glasgow
308
COMPOUND LOCOMOTIVES.
TABLE C C.— Continued.
Reference No.l
Type of Engine.
Service for which
Engine was built.
Diameter and Stroke
of Cylinders. Inches.
Diameter
of Drivers.
Inches.
III
M.£ 3
|o£
T
Forney
Elevated
9 & 15 X 16
42
40,000
2
8 Wheel
Passenger
11% & 19 X 24
68
60,000
3
«
High Speed Pass.
13 & 22 X 24
78
88,400
4
5
Special High Speed
" " "
13 & 22 X 26
14 & 24 X 24
84^
72
83,140
93)58o
6
Consolidation
Freight
14 & 24 X 26
56
134,100
7
Decapod
" .
16 & 27 X 28
50
170,000
8
9
Forney
6 Wheel
Elevated
Freight
14 & 20 X 16
i9# & 29^ X 25
42
5oK
40,000
10
ii
Mogul
10 Wheel
Fast Freight
17 & 19.7 X 27.6
18 & 28% X 24
1
90,940
76,500
12
Consolidation
Freight
13 & 22 X 26
55
130,000
13
Mogul
\\
20 & 2Q X 24
TT?X Rr TRI/£ V OT
62
._!/
97,000
*4
15
Double rJogie
8 Wheel
Passenger
II/8 Oc lo^/g A, 21
19.5 & 31 X 28
?/*
84,000
16
10 "
Freight
19 & 27 X 24
64
97,000
X7
8 "
Passenger
18 & 26 X 25.5
78
52,000
18
19
20
8 "
Consolidation
8 Wheel
Passenger & Freight
Freight
Passenger
20 & 28 X 24
20 & 30 X 24
13 & 19.7 X 23.6
69
50
79
66,000
109,088
57»3°°
21
Articulated
Freight
15.8 & 22.8 X 25.2
48.4
187,300
22
"
"
14 & 21.7 X 25.2
55-1
130,000
23
8 Wheel
Passenger
17.7 & 26.4 X 25.6
72
61,270
24
8 •
"
13.4 & 20.9 X 25.2
83.2
67,240
25
8 '
"
13 & 19.2 X 26
78-5
61,508
26
8 '
«
20 & 28 X 24
9i^
39,760
2?
o '
Freight
19 & 29 X 24
57
89,000
28
o '
"
19 & 30 X 24
56
107,100
29
o '
"
14 & 24% X 24
56
103,000
3°
o '
"
14 & 24% X 24
56
103,000
31
32
o '
Double Bogie
(i
14 & 24% X 24
13 & 22% X 24
56
48
103,000
210,000
33
Consolidation
"
13 & 22% X 24
48
100,000
34
Forney
Elevated
11% & 18 X 16
42
31,534
35
8 Wheel
Fast Passenger
18 & 28 X 24
78
66,52O
36
8 "
Passenger
19 & 28 X 24
68
66,950
37
10 "
"
19 & 28 X 26
62
92,880
38
Mogul
Freight
21 & 31 X 26
63
108,000
39
Consolidation
"
21 & 31 X 24
5°
Il8,22O
40
8 Wheel
Passenger
21 & 31 X 26
78
84,000
4i
10 "
'*
21 & 31 X 26
78
90,000
42
43
Mogul Forney
8 Wheel "
Freight
Elevated
18 & 28 X 24
13 & 21 X 28
55
44
86,000
43,000
44
10 "
Passenger
13 & 22% X 24
56
76,000
45
Consolidation
Freight
I3 & 22% X 24
48
100,000
46
Mogul
*«
20 & 29 X 26
56
107,300
47
10 Wheel
"
20 & 29 X 26
5°
97,000
48
10 "
Passenger
20 & 29 X 24
69
96,680
49
Mogul
Freight
20 & 30 X 26
57
114,500
5°
10 Wheel
Passenger
20 & 30 X 26
70
108,000
51
to "
"
20 & 30 X 24
74
106,000
52
Consolidation
Freight
20 & 29 X 24
51
113,500
53
10 Wheel
Passenger
20 & 29 X 24
74
99,000
54
6 "
'
13 & 26 X 24
81
61,264
55
6 "
'
14 & 30 X 24
75
67,200
56
6 "
i
14 & 30 X 24
85
69,440
8 "
Side Tank
\
15 & 30 X 24
14 & 26 X 24
ll'A
69,440
69,664
59
" "
'
14 & 26 X 24
68%
65,632
60
61
£.-
6 Wheel
Freight
Passenger
14 & 30 X 24
16% & 23% X 22%
r8 Kr 08 tf V oA
62%
73^
64,512
28,672
O2
63
10 Wheel
Freight
IO OL 20.5 XS 20
18 & 26 X 26
51
64
8 "
Passenger
18.5 & 25.5 X 26
59
APPENDIX.
TABLE C C.— Continued.
309
1
Reference No.l
L
•oo-
1
P!"
C^rT ""
1
^ cr
Remarks.
2
19.0
17.6
70.0
140.44
554-5
1567-07
Mos. i to 45.
' Nancy Hanks."
3
4
I
38.5
24.6
18.7
25.1
128.23
152.5
164.3
1711 .0
1478.13
i793-o
1768.0
No. 385.
' Columbia.
' Columbus."
Mo. 231.
7
89.6
234-3
2443-1
Mos. 800 to 805.
8
19.0
70.0
555-0
Mo. 46.
9
3ne of Five Engines.
10
22.5
1224.9
Built in 1888.
ii
23
112
1298
12
13
14
25-3
27.1
15
30.0
"7
126.0
59
159
1596
1506
930
1820
Mo. 324, Design of Mr. William Forsyth.
Meyer- Lindner Duplex.
Class T, Design of Mr. Axel S. Vogt.
16
28.0
1766.6
No. i.
17
,0
26.5
134.6
1572
' One of Nineteen."
IO
19
IQ. 2
69
1354
1658
Mo. 310.
20
20.4
in. 9
*3*7
21
22
23
24
23-7
19.4
21.6
22
100. I
86 i
117
1661.1
1345-6
1390.5
1211.5
12 Driving Wheel " Goliath."
8 " " Double Bogie.
With "von Borries" Starting Gear.
Designed by Mr. Du Bousquet.
25
32-3
129.1
i45i-5
Duplex.
26
20-7
123
1139.0
No. 1518.
27
.28
29
30
27-3
27-3
204
204
Six Engines.
One Engine.
2004
2004
31
32
33
28.3
43-4
21.5
213 4
274.0
148
2013.4
2570
1348
Three Engines.
One Engine.
34
16.5
56-5
299-5
35
18.5
138.0
1229
36
23-5
156.0
1425
37
29.0
165.5
1469.5
38
27.0
172
1493
39
25-0
160
1700
40
34-5
166.5
1395-5
27.0
204.0
1788.0
42
J7-5
91.0
831.0
43
44
45
17.1
17.0
2i-5
57-6
122
I48
537-5
1222
1348
No. 66, Altered from Simple Engine.
46
26.5
156
1516
47
26.5
l64
l62I
48
29-3
1736.2
No. 1785.
49
No! 15!
5°
5i
26.2
I4I.7
1953-2
No. 1503.
No. 461.
52
53
54
1
28.2
17.1
20.5
20.5
20.5
I4I.2
103.5
IS9-I
I59-I
I2O.6
1992.6
1063.7
1379-6
I40I-5
I505-7
No. 338, for " North Shore Limited."
" Experiment."
" Dreadnaught."
"Teutonic."
" Greater Britain."
58
14.24
84.8
993-6
*
59
14.24
84.8
993-6
60
17. i
94-6
1098.8
61
18.7
78-5
1047.8
Built in 1885.
62
63
22
104
1223.0
Built in 1887.
64
16
80.5
1302
GLOSSARY.
A.
Absolute Pressure. — Gauge pressure plus 14.7 pounds.
Actual Cut-Off. — The cut-off which includes a consideration of the clearance ;
the quotient of the volume of the cylinder at the cut-off point including the clearance,
divided by the total volume of the cylinder including the clearance on one end.
Actual Indicator Cards. — Cards taken from actual engines as distinguished from
elementary cards drawn according to the elementary theory of steam engines.
Angularity of Connecting Rod. — The angle which the connecting rod makes with
the line through the centre of the cylinder at any point during a revolution.
Apparent Cut-Off . — The cut-off shown by the indicator card; the cut-off measured
from the valve motion ; a cut-off that does not take into account the clearance in the
cylinders.
Atmospheric Line. — The line of no pressure as shown by steam gauge ; a line
drawn at 14.7 pounds above the line of zero of absolute pressures.
B.
Back Pressure. — The pressure in the cylinders against the piston on the return
stroke ; the pressure against which the piston is moving.
By-Pass Valve. — A valve which, when opened, permits the steam to pass from
one end of a cylinder to the other.
C.
Clearance. — The volume into which the steam left in the cylinder, when the
exhaust port is shut, is compressed; the cubical contents of the space between the
piston, when at the end of its stroke, and the face of the valve seat, including all ports
and connecting passages and indicator pipes if any.
Combined Indicator Card. — A diagram showing the cards from both cylinders
drawn to the same scale of volumes and pressures.
Compression. — Reduction of volume of the steam enclosed in the cylinder after
the exhaust opening is shut; the opposite of expansion.
Continuous Expansion. — Expansion that goes on without interruption as in a
single expansion engine; the Woolf type; the Vauclain type; the Johnstone and
the DuBousquet; expansion without pause, as in the case of receiver engines where
steam pauses in the receiver between the two expansions, viz., one in the h. p. and
one in the 1. p. cylinder.
Cut-Off. — The point where steam is shut off from admission to the cylinders; the
point of the stroke where expansion begins.
E.
Elementary Compound. — A compound engine that is assumed to give an
elementary indicator card; an engine assumed for the purpose of discussion and
illustration.
312 GLOSSARY.
Elementary Indicator Cards. — Cards that do not take into account the losses of
pressure and volume in actual engines ; sometimes called theoretical indicator cards.
Elementary Theory. — Limited theory ; theory that does not take into considera-
tion a majority of the practical conditions as distinguished from the more perfect or
complete theory.
Expansion Curve. — A curve which shows the variation of pressure during
expansion.
Inertia of Reciprocating Parts. — The tendency of reciprocating parts to remain
at rest or at a constant velocity ; the inertia is measured by the force required to get
the reciprocating parts up to speed or to reduce the speed or to stop them.
Initial Condensation. — Condensation which takes place before cut-off.
Initial Pressure. — Pressure at the beginning of the stroke.
Inside Clearance — Negative Lap. — The opening of the steam port to the exhaust
cavity of the valve when the valve is at its centre of motion.
Intercepting Valve. — The valve which prevents the steam, admitted from the
boiler to the 1. p. steam chest, from passing through the receiver to the h. p. cylinder.
L.
Link Motion. — All of the distributing apparatus such as eccentrics, links, etc.;
frequently intended to include the valve and other parts affecting the control of the
steam pressure in the cylinders.
M.
Mean Forward Pressure. — The average pressure on the piston which pushes it
forward.
N.
Negative Lap. — See Inside Clearance.
Non-Receiver Engines. — Compound engines without receivers ; continuous expan-
sion engines; the Woolf, the Vauclain, the Johnstone and the DuBousquet.
O.
Outside Lap. — The distance which the steam valve laps over the steam port when
the valve is at its centre of motion.
P.
Potential of Pressure.— The amount of pressure ; the pressure above the
atmosphere ; the intensity of pressure ; used to emphasize the fact that wire-drawing
causes a loss of potential or force; strictly, the term is equivalent to pressure.
R.
Ratio of Cylinders. — Ratio of cylinder volumes, not including clearance; where
the stroke is the same for both cylinders it is the ratio of cylinder areas.
Ratio of Expansion.— The ratio of the initial pressure to the final pressure in the
cylinder ; the quotient of the initial pressure divided by the final pressure ; sometimes
taken as the quotient of the final volume divided by the volume at cut-off, clearance
being included.
Re- Admission. — Admission of steam the second time during a stroke ; increase of
steam pressure, during admission to 1. p. cylinder caused by exhaust from h. p. cyl-
inder.
Receiver Engine. — A compound with a receptacle or receiver for the steam
exhausted from the h. p. cylinder; not a continuous expansion engine.
GLOSSARY. 313
Reciprocating Parts. — The parts that move forward and back and do not revolve ;
piston, piston rod, crosshead and part of connecting rod.
Re-Evaporation. — The evaporation of the initial condensation ; the evaporation of
moisture in the steam.
Release. — The point where the exhaust valve opens ; the end of expansion.
S.
Sequence of Cranks. — The location of cranks with respect to each other in rotation.
Single Expansion. — The expansion of steam in one cylinder; not compound.
Steam Use. — Transforming the heat in steam into mechanical work ; utilization of
steam in cylinders; method of using steam.
Super- Heating. — The heating of steam above the temperature which it normally
has at the same pressure in a steam boiler ; steam can only be super-heated when
separated from water.
T.
Tandem. — Cylinders placed one in front of the other, i, e., placed in tandem.
Total Expansion. — The ratio of the initial pressure in the h. p. cylinder to the
final pressure in the 1. p. cylinder.
V.
Valve Gear. — All of the valve motion which regulates the distribution of steam in
the cylinders.
Valve Motion. — See Valve Gear.
W.
Wire-Drawing. — Throttling steam through an aperture ; a reduction of pressure
by restricting the flow of steam ; drawing through a small opening.
INDEX.
NOTE : — The large numbers given in the body of the book in the midst of the text, refer to
the numbers of the paragraphs that treat of the same, or allied, subjects.
A.
Action of exhaust 132
Actual combined indicator cards, receiver type 57
" ratio of expansion 10
Adiabatic curve 50
" " formula for 303
Adjustments of cut-off 105
" " for engines that run in both directions 105
" " Mallett's differential 106
" " numerous examples of 111-121
" valve gear 103
Advantage of large driving wheels 21
Allan port, as affecting valve motions 131
Apparent cut-off 9
Austrian Railways, Golsdorf, starting gear 194
" " " two-cylinder compound on 194
Automatic starting gears with intercepting valves, summary about 249
" " " without intercepting valves, summary about 251
B.
Back pressure, advantage of large nozzles to reduce 137
Back pressure as affected by mufflers 258
" " at high speed 267
" " effect of exhaust on 134
" " " on by mufflers 253
" " " of small nozzles on ^34) 136
" " how it affects mean effective pressure 138
" " saving due to reduction of 137
Baldwin formula for proportions of cylinders 76
" Locomotive Works automatic intercepting valve 178
" two-cylinder compound 178
" " " (Vauclain) four-cylinder compound 215
Batchellor two-cylinder compound, Rhode Island Locomotive Works 202
Boston & Albany R. R., Dunbar tandem four-cylinder on 211
Brooks Locomotive Works four-cylinder tandem 239
" (Player) automatic intercepting valve 169
" " " (Player) two-cylinder compounds 169
" " " tandem, valve arrangement 241
" two-cylinder compound, utility of 275
" tandem starting valve 243
" " utility of 270
315
INDEX.
C.
Capacity of receiver go
" various engines 111-121
C. B. & Q. cut-off adjustment 10g
two-cylinder compound Lindner system, design of Wm. Forsyth 185
valves for h. p. cylinder i&&
Clearance 9
" calculation showing effect of on mean effective pressure 283
" non-receiver type 7
Colvin intercepting valve and separate exhaust for h. p. cylinder 208
Combined elementary indicator cards, receiver type 2
" indicator cards, area of 63
' non -receiver type , 57
' receiver type 48
Combustion as affecting economy 258
" effect on, by exhaust 256
rate of, as affecting cost of repairs 263
" saving by better 254
" " more complete 256
" reduction of rate of 356
Compound best adapted for a given service 269
" cylinder capacities of various 305
" dimensions of various 305, 307-309
" economy of, in United States 302
" future of, opinion of Axel S. Vogt 262
" how to run when disabled on one side 279
" miscellaneous designs of 248
" selection of a suitable design 277
" tests of , in U. S 301-302
" utility in case of accident to machinery 279
Compression ! T
" as affected by driving wheels 140
valve motion 123
" at high speed 267
" curve, difference between actual and hyperbola 16
" curve, modification of 13
" effect of long travel and wide outside lap of valve on 121
how affected by back pressure 138
" non -receiver type * 7
" various engines 111-121
Condensation, as shown by indicator cards 98
" " " " example of 102
causes of
97
" how to prevent 104
" in receiver 54
saving by reduction of 254> 256
Continuous expansion or Woolf type 2
" " four-cylinder 211
Cooke Locomotive Works starting gear 192
" two-cylinder compound 192
" utility of 275
Cost of repairs as affected by rate of combustion 263
Counterbalancing 139
as affected by driving wheels • 140
inertia of reciprocating parts 140
" " large drivers 140
INDEX. 317
Counterbalancing as affected by reciprocating parts 140
" distribution of centrifugal pressure over track 144
effect on, of inertia of reciprocating parts 140
formula for inertia of reciprocating parts 303
marine practice in 140
reduction of, by decrease of reciprocating parts 144
" reduction of, by increase of diameter of drivers 144
variation of centrifugal pressure on track during a revolution 144
Crank axles, disadvantage of 269
Cranks, sequence of * 83
Crosshead, Vauclain 219
Crossheads and guides, arrangement of in Vauclain compound 218
" and pistons, arrangement of, in Johnstone compound 234
Curve of equal steam weights 50
" expansion, construction of 10
" reference, for combined cards, non-receiver type 63
" saturation 50
Cut-off, actual 9
" adjustments 105
as affected by cylinder ratio and receiver capacity 106
C. B. &Q 108
for engines that run in both directions 105
" Heintzelman's, on Southern Pacific 109
Mallet's differential 106
" " early form 106
numerous examples of 111-121
Rogers Locomotive Works , 1 1 1
" apparent 9
" diagram of, in four- cylinder receiver types 294
" difference between actual and apparent 25
" effect of changing in elementary engine 38
" P. R. R. two-cylinder compound 191
Cylinder apparatus, cost of repairs to 263
" Baldwin formula for proportions of 76
" capacities of various Compounds 305
" cocks and starting gear, recent form of Vauclain 226
" Vauclain 217, 222, 224
' ' condensation in 97
" effect of large, on single expansion engines 256
" limit of oiling 255
" Mallet double 1. p '. 201
" power, per cent, of consumed by locomotives and tenders 20
" ratio, effect of on cut-off adjustments 106
" ratio of, affected by maximum width of locomotive 72
" as commonly used 73
" elementary formula for 72
" four-cylinder compound 73
" two- cylinder compound 73
" ratios, Mallet's rule for 73
" two-cylinder compounds, Mallet and Brunner 78
" von Berries' rule for 73
volumes, ratio of, to the work to be done 76, 304-5
" von Berries' formula for proportions of 77
D.
Dean automatic intercepting valve !6e
" " " " modification of . t6<;
INDEX.
Dean two-cylinder compound 165
" utility of 275
Decrease of hauling power as speed increases 22-3
" mean effective pressure as speed increases 19, 22
Diagram of rotative effort - 88
Difference between actual and apparent cut-off 25
" " " " elementary mean effective pressures 26, 29.
" compression curve and an hyperbola 16
" work and that shown by elementary indicator cards 31
" calculated and actual mean effective pressure 18
" in ratio of expansion when calculated by different rules in common use 70
Dimensions of various compounds 305 , 307-309
Distributing valve, Mallet 200
Distribution of power , two-cylinder compounds 74
" pressure on pistons, Vauclain compound 228
steam in single expansion locomotives 129
of work of three -cylinder, three-crank types 288
Double 1. p. cylinder, Mallet, Lapage 73, 78, 79
Draw bar pull, effect on by decrease of mean effective pressure 19
Driving wheels, advantage of large 21
" effect of on compression 140
" " piston speed 140
" " counterbalancing 140
" on wire-drawing 140
" as affecting counterbalancing 140
" reduction of counterbalancing by increase of diameter of 144
Drop in pressure between boiler and steam chest 133, 135
' ' during admission to h. p. cyl . 33
" " in receiver 3, 282
Du Bousquet, four-cylinder tandem compound Northern Railway of France 211
" tandem, indicator cards from 213
" " utility of 270
Dunbar four-cylinder tandem compound, Boston & Albany 211
Duplex compound, Meyer-Lindner 185
E.
Economy as affected by price of fuel 258
" " rate of combustion 259
" of compounds in U. S 301, 302
" elevated service 258
" in fast service 257
" in freight service 257
" in suburban service 257
" method of operation to gain 264
" possibilities of 254
' ' reasons for 254
" when compounds are compared with overworked single expansion engines 260
Effect of changing cut-off in elementary engine 38
" " " on receiver pressure * 40
" speed on shape of indicator cards 35
" on draw-bar pull of decrease of mean effective pressure 19
Elementary indicator cards i
' ' receiver type • 2
" of Woolf or continuous expansion type 5
Elementary indicator cards, modification of 292
" " " non- receiver type 4
INDEX. 319
Elevated and suburban service, mufflers for exhaust 136
" " saving in 258
Equalization of power, ratio of cylinders as affecting 74
" non-receiver compounds 75
work in h. p. and 1. p. cyls., conclusions 44
of a non-receiver compound 43
" of a receiver compound 42
Evaporation per pound of coal , 259
Exhaust, action of 132
" apparatus, location of 256
'• effect of, on back pressure 135
" on combustion 256
" on fire 135
" independent for h. p. cylinder 85
" mufflers in elevated and suburban service 136
" nozzles, effect of small, on back pressure 134
" saving due to action of 136
Expansion, actual ratio of 10
as affected by size of ports 255
construction of curve of 10
curve, hyperbola 103
curves, formula for 303
curve, point from which it is to be drawn 63
difference in ratio of, when estimated by different rules 70
" effect of steam passages on 255
" final pressure 281
limit of, in single expansion cylinders 256
saving by greater 255
" due to greater 254
F.
Formula for compression 13
" for mean effective pressure 17
" for receiver pressures 47
Forsyth, Wm., design of Lindner system on C., B. & Q. R. R 185
Four-cylinder compound cylinder capacity compared to two-cylinder 275
" " Johnstone, arrangement of pistons and crossheads 234
" starting gears for, summary about 252
" (Vauclain), Baldwin Locomotive Works 215
continuous expansion or Woolf type 211
" four-crank compounds, with receivers, starting of 86
four-crank types, utility of 269
" non-receiver compounds 211
non-tandem, two-crank types, utility of 272
receiver types, diagram of cut-offs in , . 294
" Paris, Lyons & Mediterranean 294-9
theoretical discussion of 293
tandem, Brooks Locomotive Works 239
compound on the Northern Railway of France, Du Bousquet 211
on Hungarian State Railways 235
on South Western Railway of Russia 237
receiver compounds 235
" compound, hauling power of 95
two-crank types, utility of 270
two-crank, hauling power of 95
32O INDEX.
Four-cylinder two-crank receiver and non-receiver compounds, starting of 85
Freight service, economy in 257
" saving in 257
Fuel, effect on train expenses 258
" comparison of American and foreign 260
" price of, as affecting economy 258
" effect on saving due to compounding 258
" price of, as affecting train expenses 258
" relative value of different kinds 259
" used per sq. ft. of grate per hour 259
German state railroads, piston valves on 122
Golsdorf (Austrian) starting gear 194
two-cylinder compound 194
" two-cylinder compound, utility of 275
Graphical representation of hauling power 87
Grate area, limit of '. 258
" fuel used per sq. ft. per hour 259
H.
Hauling power, decrease of as speed increases 22-3
" formula for 283
" graphical representation of 87
variation of with four-cylinder two-crank compounds 95
Heintzelman cut-off adjustment on Southern Pacific 109
Hungarian four-cylinder tandem, utility of 270
" State Railways, four -cylinder tandem on 235
Hyperbola as an expansion curve 49, 103
" point from which drawn 51
" formula for 303
I.
Ideal combined indicator cards 55
Increase of pressure in receiver 4
Independent exhaust for h. p. cylinder on Southern Pacific R. R 164
Indicator cards, actual, total expansion from 69
" " combined, reference curves 65
" effect of speed on shape of 35
" elementary i
" " " receiver type 2
" " " total expansion from 69
" example of small drop in pressure between boiler and steam chest 133-134
" examples showing leakage 102
" from Du Bousquet tandem 213
" " non-receiver type combined 57
" " three -cylinder three-crank types 285
" ideal, combined 55
" in practice 32
" limitations of combined 53
" losses shown by combined cards from non-receiver type 61
" " Mallet tandem Southwestern Railway of Russia 238
" method of combining non-receiver type 58
" modification of elementary 292
" " non-receiver type, correct area of combined 63
INDEX. 321
Indicator cards non-receiver type, curve of reference 63
" purposes of combining 61
" point to draw reference curve from 63
" receiver type, actual combined 57
" combined % 48
" reference curve on combined 55
" " showing advantage of large 'steam passages 134
" " condensation 98,102
" " leakage of valves 98
" re -evaporation 102
" " steam distribution by reverse lever 267
" " " steam distribution by use of throttle 265
" variations in 35
" " showing weight of steam per stroke 98
Inertia of reciprocating parts as affecting counterbalancing 140
" " formula for 303
" Vauclain compound - 228
Inside lap and negative lap, effect of 124
" " of valve 122
" negative lap, various engines 111-121
Intercepting valve and separate exhaust for h. p. cylinder (Colvin) Pittsburgh Loco. Wks. 208
" " " " " Rhode Island Locomotive Works 202
" " " Southern Pacific 164
" two-cylinder receiver compound 146
" von Borries' 209
'* and separate exhaust h. p. cylinder (Mellin) Richmond Locomotive
Works 205
" automatic, Baldwin Locomotive Works 178
" " " Rogers Locomotive Works 171
" " von Borries, early form 149
" Dean automatic 165
" " Mallet 198
" modification of Dean automatic 165
" " modification of Pitkin automatic Schenectady Locomotive Works 160
Worsdell automatic
155
Pitkin automatic, Schenectady Locomotive Works 157
" Player automatic, Brooks Locomotive Works 169
" " recent changes in von Borries' automatic 153
" " von Borries' automatic 147
ini889 J47
" modification of 152
automatic, on Jura, Berne-Lucerne 150
non- automatic 153
" Worsdell automatic !53
" early form of 154
" automatic starting gears, summary about 249
" non -automatic, summary about 251
J-
Johnstone four-cylinder compound, arrangement of pistons and crossheads 234
OH Mexican Central 233
" " " utility of 272
L.
Lapage double J. p. cylinder 78
Leakage as shown by indicator cards, example of IO2
" of valves, as shown by indicator cards 08
322 INDEX.
Limitations of combined indicator cards 53
Lindner automatic starting gear 181
" modification of 184
" * " on Saxon State R. R 185
" diagram of turning moment of two-cylinder compounds 299
" Meyer duplex compound 185
" starting power 94
" two-cylinder on C., B. & Q., design of Wm. Forsyth 185
on P. R. R. design of Axel S. Vogt 188
" two-cylinder compound 181
" utility of 275
Locomotive test at Purdue University. 68
Loss due to drop of receiver pressure 47
" " use of mufflers 136
" " wire-drawing 132
" in pressure, non- receiver type 6
Losses shown by combined cards of non-receiver type 61
Low-pressure cylinder, re-admission in 34
M.
Mallet, as originator of practical compounds 146
" differential cut-off adjustment *. 106
" distributing valve 200
" double 1. p. cylinder 73, 201
" early form of cut-off adjustment 106
" intercepting valve 198
" preliminary work of 201
" rule for ratios of cylinders. . 73
" starting valve 197
" system, early form of 199
" " on Western Switzerland Railway 196
" " starting power of 90
" " with separate exhaust for h. p. cylinder 196
" tandem on Southwestern Railway of Russia, indicator cards from 238
" " piston for 237
" " utility of 270
" two-cylinder compound 196
" utility of 275
Mean effective pressure at high speed 267
" decrease of as speed increases 19, 22
" difference between actual and elementary in h. p. cylinder 26
" " " " " " " 1. p. cylinder 29
" " " " calculated and actual 18
" " " equivalent in one cylinder 282
" " " example of calculation of 281
" " " " " including clearance 283
" " " formula for 17
" how it affects back pressure 138
Mellin automatic intercepting valve and separate exhaust for h. p. cylinder, Richmond
Locomotive Works 205
" two-cylinder compound, Richmond Locomotive W'orks 205
Method of combining cards of non-receiver type 58
" operation, necessity for wide-open throttle 132
Mexican Central Ry., Johnstone four-cylinder compound on 233
Meyer-Lindner duplex compound 185
Miscellaneous designs that have not been put in service 248
INDEX. 323
Modification of compression curve '. 13
Mufflers, effect on back pressure.. .. .-.. 25%
" exhaust, in elevated and suburban service t 136
" loss due to use of 136
N.
Negative lap, effect of at low speeds 125, 127-128
conclusion about 130
example of small effect of 129
inside lap, effect of 124
" large on P. R. R. compound 130
of valve, P. R. R. two-cylinder compound 191
various engines 111-121
Non-automatic intercepting valves, summary about , 251
starting gears, starting power of go
" " summary about 251
Non-receiver compounds, ratio of cylinders and equalization of power in 75:
type, clearance 7
" compression 7
"• loss in pressure 6
" of elementary indicator cards 4
Northern Railway of France, four-cylinder tandem on 211
" three -cylinder compound 246
" valve gear 247
Nozzle, advantage of large on back pressure ^y
exhaust, effect of small on back pressure 134, 13(3
O.
Oiling of cylinders, limit of 2eg
Operation, method of, to gain economy 2g ,
'•' of compounds when disabled on one side 270
" of locomotives, proper, saving effected by 264
Outside lap, effect on valve motion of increasing I2,
" and long valve travel on Philadelphia & Reading R. R I24, I26
" for various engines ' 111-121
" of valve I22
of valve, P. R. R. two-cylinder compound 1gI
P.
Paris, Lyons & Mediterranean, four-cylinder receiver types 294-299
Patents, variety of j. g
Penn. R. R., piston valves igo
P. R. R. two-cylinder compound, Lindner system, design of Axel S. Vogt jgg
Per cent, of total cylinder power consumed by locomotives and tenders 2O
Philadelphia & Reading R. R. valve motions I2. I2g
Piston for Mallet tandem
" speed, effect of large drivers on o
" valve bushing, on Vauclain compound 2I_
" valve, Vauclain 2l6j 2I?
122
' for P. R. R. two-cylinder compound Igo
" on German State Railroads I2_
Pistons and crossheads, Johnstone four -cylinder type 2, .
" distribution of pressure on, Vauclain compound 22g
324 INDEX.
Pitkin automatic intercepting valve 157
" modification of automatic intercepting valve 160
" two-cylinder compound 157
Pittsburgh Locomotive Works (Colvin) intercepting valve and separate exhaust for
h. p. cylinder 208
Locomotive Works (Colvin) two -cylinder compound 208
" two-cylinder compound, utility of 275
Player automatic intercepting valve, Brooks Locomotive Works 169
" two-cylinder compound, Brooks Locomotive Works 169
Point from which to draw hyperbola 51
Port openings, P. R. R. two-cylinder compound 191
" " various engines in -121
Ports, dimensions of 77
" effect of on expansion 255
Power, distribution of, two -cylinder compounds 74
" starting with close-coupled cars and free slack 84
Pressure, drop in, during admission to h. p. cylinder 33
" in receiver 40, 44
" effect of a change of cut-off on 40
Proportions of cylinders, Baldwin formula 76
" von Borries' rule for 77
Purdue University, engine test at 68
R.
Radiation, as prevented on Old Colony engine 98
" effect of 97
" need of covering hot surfaces 97
" neglect of consideration of .' ; 97
" saving by reduction of 256
Rate of combustion, effect on economy 259
Ratio of cylinders and equalization of power in non- receiver compounds 75
" " as affected by maximum width of locomotive 72
" " as affecting equalization of power in two-cylinder receiver compounds. ... 74
" " commonly used 73
" " elementary formulas for 72
" " four-cylinder compound 73
" " Mallet's rule for 73
" " two-cylinder compound 73
" " volumes to the work to be done 76
" " von Borries' rule for 73
Re-admission in 1. p. cylinder 34
Receiver, calculation for pressure in 281
" capacity 80
" " effect of on cut-off adjustment 106
" " P. R. R. two-cylinder compound 192
" " various engines 111-121
" condensation in 54
" drop in pressure in 3» 2^2
" increase of " 4
" pressure 4°> 44
" " elementary engine, effect of a change of cut-off in 40
" pressures, formula for 47
" " loss due to drop of 47
" re-evaporation in 54> 82
" re-heating in 276
INDEX. 325
Receiver super-heating in 54
" type of elementary indicator cards 2
" volume of, von Borries' rule 77
Reciprocating parts, American and foreign _ ^n
" "as affecting counterbalancing 140, 144
" comparative effect of American and foreign 143
" effect of heavy I3g
" " example of reduction of 140
" formula for inertia of 303
" heavier for compounds I3g
" inertia of, Vauclain compound 228
" necessity for reduction of weight of I3g
" reduction of counterbalancing by decrease of 144
" weight of _ !39
Re -evaporation as shown by indicator cards 98
" example of 98, 102
during expansion, cause of IO3
in receiver 54,82
of condensed steam in cylinders, 52, 66.
Reference curve on combined indicator cards 55
rectangular hyperbola 49
Re-heating and steam jackets 80
in receiver 276
Repairs, cost of 259, 262
" as effected by boiler. . 263
" as compared to savings 264
" to cylinder apparatus 263
Reverse lever, indicator cards, showing steam distribution by 267
Rhode Island Locomotive Works (Batchellor) two-cylinder compound 202
" intercepting valve and separate exhaust for h. p. cylinder.. 202
two-cylinder compound, claims for 205
utility of 275
Richmond Locomotive Works (Mellin) automatic intercepting valve and separate exhaust
for h. p. cylinder 205
" (Mellin) two-cylinder compound 205
" " two-cylinder compound, utility of 275
Rogers Locomotive Works automatic intercepting valve 171
" cut-off adjustment I0g
" two-cylinder compound 171
" utility of 275
Rotative effort, diagrams of 88, 93-94
s.
Saturation curve , 50
formula for. . .
303
Saving as affected by price of fuel _, 258
" by proper operation of locomotives 264
" " by rate of combustion 258
" by greater expansion 254? 255
" more complete combustion 254, 256
" reduction of condensation 254
" reduction of radiation 256
" due to action of exhaust 136
in elevated service 258
" in fast service 257
INDEX.
Saving in freight service 257
" in. slow service 257
" in suburban service 257
" of compounds in U. S 301, 302
" comparison of cost of repairs to 264
" posibilities of • 254
" reported from tests 254
" when compounds are compared with over-worked single expansion engines 260
Saxon State R. R., Lindner starting gear on 185
Schenectady (Pitkin) automatic intercepting valve 157
" " " " " modification of 160
" " two-cylinder compound, utility of 275
Selection of type for a given service 269
Separate exhaust for h. p. cylinder and intercepting valve (Colvin) Pittsburgh Locomotive
Works 208
" " for h. p. cylinder, Mallet system 196
" for h. p. cylinder and automatic intercepting valve (Mellin) 205
" for h. p. cylinder and intercepting valve, Rhode Island Locomotive Works, 202
" for h. p. cylinder and intercepting valve, von Borries 209
" for h. p. cylinder, summary about 251
" for h. p. cylinder, two -cylinder receiver compound 146
Sequence of cranks 83
Shop tests 68, 255
Single expansion locomotives, starting and hauling power of 86
Size of port openings, various engines 111-121
" steam passages i32
Slide valves, proportion of, von Borries 77, 7%
Smoke box temperatures - - - 82
Southern Pacific R. R., independent exhaust for h. p. cylinder on 164
Southwestern Railway of Russia, tandem four-cylinder on 237
Speed, high, steam distribution at 267
Starting and hauling power of single expansion locomotives 86
" gear and cylinder cocks, recent form of Vauclain 226
" « " " Vauclain 217,222,224
" " automatic, with intercepting valves, summary about •. 249
" " Cooke Locomotive Works i92
" " for four-cylinder compounds, summary about 252
" Golsdorf (Austrian) i94
" " Lindner automatic 181
on Saxon State R. R 185
" " modification of Lindner automatic 184
" " non- automatic, summary about 251
" " summary about 249
" of four-cylinder two-crank receiver and non-receiver compounds 85
" of two-cylinder receiver compounds with independent exhaust for h. p. cylinder 85
« " " without an independent exhaust for h. p.
cylinder 84
" power, Lindner type 94
" " of four-cylinder four-crank compounds with receivers 86
" " of three -cylinder three-crank compounds 95
Webb type 95
'• " with automatic gears 91
" with Mallet's system and other non-automatic starting gears 90
" valve, Brooks Locomotive Works tandem compound 243
" Mallet 197
" with close-coupled cars and free slack 84
INDEX. 327
Steam chest, drop in pressure between boiler and 133
example of small drop in pressure between boiler and 133-4
pressure, drop from boiler 135
" variation in T33> 136
Steam, condensed, re-evaporation of . . . * 66
" distribution at high speed 267
" " by reverse lever, indicator cards showing 267
" in three -cylinder three-crank types 284
" in Vauclain compound 220
" Vauclain compound, slow speed 275
" jackets 80
passages 132
" effect on expansion 255
" indicator cards showing advantage of large size of 134
" re -evaporation of condensed in cylinders 52
" weight of at different points of the stroke 101 , 104
" weight of per stroke , 51, 64
for various compounds, calculated from indicator cards 66
" weight of retained in cylinder at end of compression 52
" weights, curve of equal 50
Stuffing-boxes, h. p. and 1. p. combined in one 271
Suburban service, mufflers for exhaust 136
" " saving in 257
Super-heat, due to wire-drawing 132
Super-heating in receiver 54
T.
Tandem, Brooks Locomotive Works starting valve for 243
" valve arrangement 241
" compound, Dunbar four-cylinder on .Boston & Albany R. R 211
" four -cylinder, on Northern Railway of France 211
" four-cylinder on Hungarian State Railways 235
" " on Southwestern Railway of Russia 237
receiver compounds 235
" indicator cards from DuBousquet 213
" Mallet, piston for 237
" receiver compounds, starting of 86
Temperatures of smoke boxes 82
range of, in cylinders 97
Tests in shop 68, 255
" of compounds in U. S. (Table) 301-302
" projected Master Mechanics Association 255
" reported savings 254
Three and four-crank compounds 244
summary about 248
Three -cylinder compound on Northern Railways of France 246
" " " " valve gear for, 129
Webb 244
three-crank types 284
" " diagram of turning moment 289-290
" distribution of work 288
" " indicator cards 285
" starting power 95
" steam distribution in 284
" " " utility of 270
328
INDEX.
Three-cylinder Webb, express compound 244
" freight " 245
" " on P. R. R 245
Throttle, effect of wire -drawing 264
" necessity for wide open, in operating 131
Total cylinder power, per cent, of consumed by locomotives and tenders 20
" expansion from actual indicator cards 69
" " " elementary " " 69
Tractive force, formula for 283
" power, formula 86, 88
Train expenses as affected by price of fuel 258
" " with different train loads 260
Travel of valve 122
" " various engines 111-121
Turning moment, diagram of, Lindner compound 299
diagram of, three -cylinder, three-crank type 289-290
" two -cylinder compounds, Lindner 299
Two-cylinder compound, Baldwin Locomotive Works 178
" " Brooks " 169
" " Cooke " 192
" " cylinder capacity compared to four-cylinder compound 275
" " " ratio of Mallett and Brunner 78
" Dean 165
" " Gdlsdorf (Austrian) 194
" " Lindner 181
" " " diagram of turning moment 299
" " " on C., B. & Q., design of Wm. Forsyth 185
" " '• system, P. R. R., design of Axel S. Vogt 188
" " Pitkin, Schenectady Locomotive Works 157
" " Pittsburgh Locomotive Works (Colvin) system 208
" " (Player) Brooks Locomotive Works 169
'• " Rhode Island Locomotive Works (Batchellor) 202
" •' " " " claims for 205
" " Richmond " " (Mellin) 205
'• " Rogers " " 171
" " ratio of cylinders as affecting equalization of power in 74
" " utility of 275
" " valve adjustment 276
" " von Borries i47> 209
" " with automatic intercepting valve and separate exhaust for h. p.
cylinder 146, 196
" with independent exhaust for h. p. cylinder, starting of 85
" without independent exhaust for h. p. cylinder, starting of 84
valve and without independent exhaust for
h. p. cylinder 181
Worsdell type 153
" two-crank receiver types, utility of 275
Types of compound locomotives commonly used 2
Valve adjustment, two-cylinder compound 276
" arrangement, Brooks tandem 241
" for h. p. cylinder, C. B. &. Q. compound 188
" gear adjustments 103
" " for three -cylinder compound on Northern Ry. of France 247
" " proportions of , tandem compound 8
INDEX. 329
Valve inside lap of 122
" motion, as affecting compression 123
" " wire-drawing 123
" conclusions about dimensions 130
" " " negative lap , 130
" " '" " valve travel 131
" effect of Allan port 131
" effect of increasing outside lap on 124
" " " " valve travel 124
" " inside lap and negative lap 124
" negative lap at low speeds 125, 127- 128
" on expansion 255
" " example of small effect of negative lap 129
" " good-steam distribution in single expansion locomotive 129
" large negative lap on P. R. R. compound 130
" long valve travel and outside lap on Philadelphia & Reading R. R 124,126
" meaning of term as here used • 73
" " some effects of inadequate i 123
" negative lap, P. R. R.. two-cylinder compound 191
" outside lap of 122
" P. R. R. two-cylinder compound 191
" various engines 111-121
" piston 122
" " bushing for, Vauclain compound 217
" " Vauclain 216
" slide, proportions of, two- cylinder compound, von Borries' 77, 78
" travel, effect of increasing 124
" long travel and wide outside lap on compression 121
" " long, and outside lap on Philadelphia & Reading R.R. , 124,126
" " of 122
" " P. R.R. two-cylinder compound 191
" " valve motions, conclusions about 131
" " various engines 111-121
Variations in indicator cards 35
Vauclain compound, arrangement of crossheads and guides 218
" " claims for 232
" cylinders 216
" distribution of pressure on pistons 228
" inertia of reciprocating parts in 228
" steam distribution at slow speed 275
" utility of 272
"; crosshead 219
" four- cylinder compounds, Baldwin Locomotive Works 215
" piston valves 216-217
" " bushing 217
" starting gear and cylinder cocks 217, 222-224
" recent form of 226
" steam distribution 220
Vogt, Axel S., design of two-cylinder compound on P. R.R., Lindner system 188
von Borries' automatic intercepting valve 147
" early form of 149
" in 1889 147
" modification of 152
"» " on Jura, Berne -Lucerne 150
" recent changes in 153
" formula for proportions of cylinders 77
33O INDEX.
von Berries' intercepting valve and separate exhaust for h. p. cylinder 209
" non- automatic intercepting valve 153
" rule for cylinder ratios 73
two-cylinder compound *47> 209
two- cylinder compound, utility of 275
type, starting power of 71
w.
Webb three-cylinder compound 244
; ' express compound 244
freight compound 245
" " on P. R. R 245
Weight of steam different points of the stroke 101 , 104
" per stroke 51, 64, 101
" as shown by indicator cards 98
" for various compounds, calculated from indicator cards 66
" retained in cylinder at end of compression 52
Western Switzerland R. R., Mallet system on 196
Wire-drawing as affected by driving wheels 140
" " valve motions 123
" at high speed 267
effect of, on economy 264
" " on throttle 264
" loss due to .... ~ ... 13
super-heat due to 13
Woolf or continuous expansion types
type, elementary indicator cards
" " four-cylinder : 21
Work, conclusions about equalization in h. p. and 1. p. cylinders 44
" difference between actual and that shown by elementary indicator cards 31
" equalization of, in h. p. and 1. p. cylinders of a non-receiver compound 43
a receiver compound 42
" to be done, ratio of cylinder volumes to 76
Worsdell automatic intercepting valve 153
" early form of 154
" modification of 155
" two-cylinder compound, starting power of 91
utility of 275
Worsdell type of two-cylinder compound 153
RECENT PUBLICATIONS
OF THE
RAILWAY AGE AND NORTHWESTERN RAILROADER,
Papers and Addresses of the World's Railway Commerce Con-
gress of 1893. Cloth $3.00
This is one of the most notable and valuable publications of the kind ever
offered to the public. It contains papers by the following widely-known writers
and railway men : George R. Blanchard, Commissioner Central Traffic Associa-
tion ; Hon. John F. Dillon, General Counsel Union Pacific Railway ; Hon.
W. G. Veazey, member Inter-State Commerce Commission ; Edward P. Ripley,
Vice-President Chicago, Milwaukee & St. Paul Railway Co.; Hon. Martin A.
Knapp, member Interstate Commerce Commission; John W. Gary, General
Counsel Chicago, Milwaukee & St. Paul Railway Co.; Alfred G. Safford, Law
Department Interstate Commerce Commission; M. M. Kirkman, Vice-President
Chicago & North-Western Railway; Aldace F. Walker, Chairman Joint Com-
mittee Trunk Lines and Central Traffic Association; E. W. Meddaugh, General
Solicitor Chicago & Grand Trunk Railway Co.; H. S. Haines, Vice-President
Plant Railway System; William E. Curtis, Representative United States
Department of State, World's Columbian Exposition ; George H. Heafford,
General Passenger and Ticket Agent Chicago, Milwaukee & St. Paul Railway;
R. C. Richards, General Claim Agent Chicago & North-Western Railway;
Gen. Horace H. Porter, Vice-President Pullman's Palace Car Co.; A. W. Soper,
New York; L. J. Seargeant, General Manager Grand Trunk Railway of Canada;
L. S. Coffin, Ft. Dodge, la.; Kirtland H. Wade, General Manager California
Southern Railway; S. R. Barr, Superintendent Relief Department Baltimore &
Ohio Railroad; R. F. Smith, Superintendent Relief Department Pennsylvania
Lines West of Pittsburgh; Jos. Nimmo, Jr., late Statistician U. S. Treasury De-
partment; George P. Neele, Superintendent of the Line, London and North-
Western Railway, London, England; the Traffic Manager of the Royal State
Railway of Sweden.
The Biographical Directory of Railway Officials of America —
Edition of 1893. 420 pp. Cloth. Price, postpaid $3.00
This is an invaluable book of reference for railroad men, libraries, news-
papers, etc. It gives concisely the important facts in the careers of four
thousand railway officials.
" It is one of the most useful railway reference books printed, and the fullness
of its information, coupled with its brevity, makes its 418 pages as compact in
information and as valuable in its way as Webster's Dictionary.'1'' — Buffalo
Express.
" The whole is compactly arranged and excellently printed, making a con-
venient and useful book of reference.'" — The Railroad Gazette.
" The scheme is a good one and is well carried out in the manner of presen-
tation.'1'1— Engineering News.
" To the general public a book such as this conveys a good idea of the vastness
of the railroad business in the United States, which requires 'so many principal
officers to look after it. It is well printed, and a great deal of information in
regard to each person is given in the most concise manner possible.''1 — 7 he Iron
Age.
THE RAILWAY AGE AND NORTHWESTERN RAILROADER,
1452-1456 MONADNOCK BLOCK,
CHICAGO.
RECENT PUBLICATIONS
OF THE
RAILWAY AGE AND NORTHWESTERN RAILROADER.
The Protection of Railroad Interests. By JAMES F. How, Vice-
President of the Wabash Railroad. Pamphlet. Price, postpaid $ .25
This pamphlet should be read by everyone interested in the welfare of
American Railways. It is brief, pointed, suggestive, and an earnest appeal to
railway managers to stand together againgt demagogic encroachments upon the
rights of railway property.
The Interstate Commerce Act and the Car Coupler Law.
Pamphlet. Price, postpaid $-25
This pamphlet contains the full act to regulate commerce, as amended to
date, and of the supplementary act relating to the testimony of witnesses before
the inter-state commerce commission, together with the full text of the " Safety
Equipment Law," relating to the compulsory application of automatic car-
couplers and air-brakes. The work is thoroughly indexed and the arrangement
of the side heads renders it exceptionally convenient for ready reference.
The Railway Age and Northwestern Railroader. A weekly
journal of railway transportation, equipment, operation and
finance. Price per annum, postage free $4.00
This journal stands at the head of its class. It has the largest circulation
of any weekly railroad paper published in the world. It is the only paper that
covers the whole field of railway affairf comprehensively. It gives every week
the fullest information concerning whatever is newest in railway politics, railway
engineering, railway mechanics, railway law, railway construction, railway
operation, railway management, railway surgery, and railway finance. Sample
copy free.
The Rights and Wrongs of the Railway Question. Pamphlet.
Price, postpaid $ .25
This is a collection of articles reprinted from the Railway Age and North-
western Railroader, giving the facts of the railway problem as it interests the
public. The object of this publication is to give these facts in a form pleasant
to read and easy to digest. It is replete with most valuable information for any
one interested in the railway question.
THE RAILWAY AGE AND NORTHWESTERN RAILROADER,
1452-1456 MONADNOCK BLOCK,
CHICAGO.
RETURN CIRCULATION DEPARTMENT
TO— * 202 Main Library
LOAN PERIOD 1
HOME USE
2
3
4
5
6
ALL BOOKS MAY BE RECALLED AFTER 7 DAYS
1 -month loans may be renewed by calling 642-3405
6-month loans may be recharged by bringing books to Circulation Desk
Renewals and recharges may be made 4 days prior to due date
DUE AS STAMPED BELOW
i CLF
UNIVERSITY OF CALIFORNIA, BERKELEY
FORM NO. DD6, 60m, 3/80 BERKELEY, CA 94720
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11