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