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RAILWAY SIGNALING






PUBLISHERS OF BOOKS F O R^

Coal Age v Electric Railway Journal

Electrical World ^ Engineering News-Record

American Machinist ^ Ingenieria Internacional

Engineering 8 Mining Journal ^ Power

Chemical 6 Metallurgical Engineering

Electrical Merchandising



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RAILWAY SIGNALING



BY

EVERETT EDGAR KING

MEMBER OF THE AMERICAN RAILWAY ASSOCIATION, SIGNAL SECTION; MEMBER OF THE

AMERICAN' RAILWAY ENGINEERING ASSOCIATION; ASSOCIATE MEMBER OF

THE AMERICAN SOCIETY OF CIVIL ENGINEEBS; PROFE88OB

OF RAILWAY CIVIL ENGINEERING IN THE

UNIVERSITY OF ILLINOIS.






FIRST EDITION



McGRAW-HILL BOOK COMPANY, INC.
NEW YORK: 370 SEVENTH AVENUE

LONDON: 6 & 8 BOUVERIE ST., E. C. 4
1921







COPYRIGHT, 1921, BY THE
McGRAw-HiLL BOOK COMPANY, INC.



THE MAPI.B: J'KKSS YORK PA



PREFACE

v

It is the purpose of this boqk to collect from various sources
that which is already in use in common practice in the fieldjef^
railway signaling and to present it in text-book form suitable for
the beginner in his study of this subject. Much of the descriptive
material and many of the drawings were furnished by the various
signal and supply companies specially for this book. Otrier
descriptions and drawings were taken from catalogues and
descriptive literature issued by these companies. I have not
included any thing concerning specifications for the construction,
installation and maintenance of materials. This is a voluminous
subject in itself; besides, specifications for practically every item of
equipment that enters into railway signaling are provided for in
the Manual of the American Railway Association, Signal Section.

In a few cases, I have quoted from the Proceedings of the
American Railway Engineering Association, from the Signal
Dictionary and from the Railway Signal Engineer. As I have
drawn so largely from the Proceedings of the Railway Signal
Association, it might be pertinent to state briefly that in its
early days the organization was known as the Railway Signaling
Club. Later it changed its name to the Railway Signal Associa-
tion; and recently during the time when the railways were under
the supervision of the Director General of Railroads, United
States Railroad Administration, the organization amalgamated
with the American Railway Association and took the name which
it still retains, the American Railway Association, Signal Section.
I might state in this connection, also, that the Manual and all the
Proceedings of the organization under both the old and new re-
gimes may be obtained from the Secretary, Mr. H. S. Balliet, 75
Church St., New York.

I want to express my appreciation for the help received from
all sources, for the material furnished, for the suggestions offered
and for the corrections made in the preparation of the manu-
script. I am especially indebted to the Union Switch and Signal
Company, the General Railway Signal Company, The Federal
Signal Company, and the Hall Switch and Signal Company for



460152



vi PREFACE

the photographs and drawings that I have selected and used for
general illustrations. I am equally indebted to all the companies
that have furnished photographs and drawings that illustrate
their particular line of equipment. I am likewise indebted to
the Board of Directors of the American Railway Association,
Signal Section, for permitting me to use the many cuts and quo-
tations that I have included in the text. I appreciate very much
the assistance given by Mr. G. A. Blackmore of the Union Switch
and Signal Company, by Mr. A. G. Moore of the General Railway
Signal Company, and Mr. S. J. Turreff of the Federal Signal
Company. I am especially grateful to Mr. Balliet for sugges-
tions and corrections that he has offered in the preparation of the
manuscript, and to Mr. S. E. Gillespie for his kindness in prepar-
ing some of the material for the original manuscript and for
his valuable suggestions while reviewing and proof-reading the
major portion of the remainder of it.

E. E. KING.
URBAN A, ILL.
September, 1921.



CONTENTS

CHAPTER I

PRELIMINARY
ART. p AGE

1. Introductory 1

2. History 1

3. Organization 2

4. Rules for Signal Supervisors and Signal Foremen 5

5. Commissions 7



CHAPTER II
SIGNAL INDICATIONS

6. Two- and Three-position Semaphore Signal Indications 8

7. Color Lights for Day Indications 11

8. Position-light Signals 12

9. Disc Signals 14

10. Take Siding Signal 17

11. Relative Location of Signals and Tracks 19

CHAPTER III
INTERLOCKING

12. Definition 22

13. Object 22

14. General Plan 23

15. General Order of Locking Signals and Derails 25

16. Locking Sheet 26

17. Diverging Routes 28

18. Movable Bridge Interlocking 30

19. Requirements for the Protection of Traffic at Movable Bridges . 32

20. Track Diagram and Manipulation Chart 35

CHAPTER IV

MECHANICAL INTERLOCKING
INTERLOCKING MACHINES

21. General 36

22. Horizontal Locking 36

23. Special Locking 39

24. Vertical Locking 40

vii



viii CONTENTS

ART. PAGE

25. Special Locking ' 42

26. The Dog Chart 44

27. Stevens Interlocking Machine 48

CHAPTER V
MECHANICAL INTERLOCKING

OTHER EQUIPMENT

28. Leadouts 49

29. Pipes and Couplings 50

30. Stuffing Box 50

31. Pipe Carriers .'..... 50

32. Compensators 51

33. Field Construction of Pipe Lines 55

34. Horizontal Cranks and Radial Arms 57

35. Crank, Wheel, Compensator, and Pipe Carrier Foundations ... 58

36. Facing Point Lock 59

37. Switch and Lock Movement 59

38. Detector Bar . 60

39. Bolt Lock 60

40. Head Rod and Switch Adjustment .62

41. Lock Rod 63

42. Derails 65

43. Crossing Bars 66

44. Semaphore Signals 67

45. Dwarf Signals 69

46. Time Lock 69

47. Calling-on Arm 73

48. Movable Bridge Couplers and Locks 74

49. Rules 75

CHAPTER VI
ELECTRO- PNEUMATIC INTERLOCKING

50. Ah- Supply 78

51. Electricity 80

52. General Sequence in Power Interlocking 80

53. Interlocking Machine 81

54. Mechanism for Throwing Switches and Derails 87

55. Indication Circuit Controller 90

56. Indication Relays ...... 90

57. Detector Locking. ..-.>.. 94

58. "SS" Control 94

59. Throwing a Switch 94

60. Signal Operating Mechanism 98

61. Operating a Signal. 99

62. Advantages ". 101



CONTENTS ix
CHAPTER VII
ELECTRIC INTERLOCKING

GENERAL RAILWAY SIGNAL COMPANY SYSTEM

IRT. PAGE

63. Electricity 102

64. Operating Switchboard . ..... ... .... . . . . . . . . 102

65. Interlocking Machine. . . . . 103

66. Switch Lever Wiring ;.-...... 107

67. Model 2 Switch Machine . . ' 108

68. Model 4 Switch Machine 113

69. Model 5 Switch Machine . . . ... . . .... . . ... . 113

70. Semi-automatic Signal Control 115

71. Dwarf Signals 118

72. Cross Protection /-...-. 119

73. Alternating-current Interlocking 121

74. Illuminated Track Diagram 122

75. Electro-mechanical Interlocking Machine 123

UNION SWITCH AND SIGNAL COMPANY TYPE "F" SYSTEM

76. General 124

77. Power Supply 124

78. Interlocking Machine. 124

79. Power Mains 125

80. The Indicating System 127

81. Style " M " Switch Movement 128

82. "SS" Control 131

83. Auxiliary Features 133

84. Union "S-7" and "S-8" Electro-mechanical Interlocking Ma-

chines 133

85. Union "P-5" Electro-mechanical Machine 135

FEDERAL SIGNAL COMPANY SYSTEM

86. Interlocking Machine 135

87. Type 41 Switch Machine . . * 138

88. Switch Machine Control and Indication Circuits . . 141

89. Federal Electro-mechanical Interlocking Machine 143

HALL SWITCH AND SIGNAL COMPANY SYSTEM

90. Interlocking Machine . 144

91. Switch Movement 145

92. Switch Operating Circuits . ..... . . ........... 146

93. Signal Operating Circuits < ..... 146

94. Indication Current 148

95. Switch Indication Circuit 148

96. Signal Indication Circuit 148



X CONTENTS

CHAPTER VIII

DIRECT-CURRENT TRACK CIRCUITS

ART. PAGE

97. Track Circuits 149

98. Cut Sections 150

99. Fouling Circuits 151

100. Insulated Rail Joints 151

101. Rail Bonds for Track Circuits 152

102. Neutral Relay 152

103. Polarized Relays 156

104. Track and Signal Batteries 157

105. Battery Wells and Battery Chutes 160

106. Cable and Relay Posts 160

107. Trunking 161

108. Insulated Head, Front, and Tie Rods 162

109. Lightning Arresters 162

CHAPTER IX
ELECTRIC LOCKING

110. Wiring Diagrams for Electric Locks 166

111. Section Locking 171

112. Screw Release 173

113. Clock-work Time Release 173

114. Approach Locking 174

115. Route Locking 176

116. Sectional Route Locking 177

117. Stick Locking 177

118. Stick Relay 179

119. Check Locking ' 179

120. Union Electro-mechanical Slot 180

121. Hall Electro-mechanical Slot 183

122. Tower Indicators ' 185

CHAPTER X
MANUAL BLOCK SYSTEM

THE MANUAL BLOCK

123. General Description 186

THE CONTROLLED-MANUAL BLOCK

124. General Description 187

THE ELECTRIC TRAIN STAFF

125. General 189

126. Operation of the Absolute Staff Instrument 190

127. The Permissive Staff 194

128. Intermediate Siding and Junction Instruments 196

129. Pusher Attachment .197



CONTENTS xi

CHAPTER XI
AUTOMATIC BLOCK SIGNALING ON DOUBLE TRACK

GENERAL

ART. PAGE

130. Object 198

131. Location of Signals 199

132. Two-position Semaphore Signaling 201

133. Three-position Signaling 202

134. Overlap Systems 203

135. Absolute and Permissive Signaling on Double Track 203

136. Three-block Indication Scheme 206

137. Numbering Automatic Signal Posts 206

CHAPTER XII

AUTOMATIC BLOCK SIGNALING ON DOUBLE TRACK

DIRECT-CURRENT TRACK CIRCUITS

NORMAL CLEAR SIGNALS

138. Two-position Signal Circuits 208

139. Two-position Polarized Track Circuits 209

140. Three-position Signal Circuits 211

141. Three-position Polarized Track Circuits . ....... 213

NORMAL DANGER SIGNALS

142. Two-position Signal Circuits 213

SWITCH, CURVE, AND SIDING PROTECTION

143. Switch Indicators 214

144. Switch Box ,. 215

145. Signals for Outlying Switches and Obscure Curves 216

CHAPTER XIII

AUTOMATIC BLOCK SIGNALING ON DOUBLE TRACK
AS ALTERNATING CURRENT

146. Introductory 217

SINGLE-RAIL RETURN

147. Direct-current Propulsion 218

148. Impedance Coil 221

149. Track Transformer 222

DOUBLE-RAIL RETURN

150. Direct-current Propulsion 222

151. Alternating-current Propulsion 227

ALTERNATING-CURRENT SIGNALING ON STEAM ROADS

152. General 227



xii CONTENTS

TRANSFORMERS

ART. PAGE

153. General . . ^ ; > . . . . . . . . 228

ALTERNATING-CURRENT RELAYS

154. General 230

UNION SWITCH AND SIGNAL COMPANY DESIGNS

155. Vane Type ........ 230

156. Ironless Galvanometer Type. ....... ., . . 231

157. Iron Core Galvanometer Type ...... . . . 232

158. Centrifugal Frequency Relay . ,.. 233

159. Radial Contact Polyphase Induction Type . . ... . ... . . . 234

GENERAL RAILWAY SIGNAL COMPANY DESIGNS

160. Universal Alternating Current Relay . 234

161. Models 2A and 2B Two- and Three-position Relays 235

162. Model 2A Two-position Centrifugal Frequency Relay 236

ALTERNATING-CURRENT TRACK AND SIGNAL CIRCUITS

163. Two-position Signals 237

164. Three-position Signals . . 240

CHAPTER XIV

AUTOMATIC BLOCK SIGNALING ON SINGLE TRACK

165. General 249

166. Union General and Special Plans TDB System 249

167. General Railway Signal, General, and Special Plans, A. P. Block

System 259

168. Other Installations 262

CHAPTER XV

SIGNAL MECHANISMS

TWO-POSITION SIGNALS

169. Hall Disc Signal ] 271

170. Union Style "B" Signal 272

THREE-POSITION SIGNALS

171. Union Electro-pneumatic Signal 275

172. Union Style "S" Signal 275

173. Union Style "T-2" Signal 276

174. General Railway Signal Model "2A" Signal 279

175. Hall Three-position Style "K" Signal 283

176. Hall Style "L" Signal , 284

177. Federal Three-position Type ' 4" Signal 285



CONTENTS xiii

AUTOMATIC STOPS

ART. PAGE

178. Motor-operated Automatic Stops 288

LIGHT SIGNALS

179. General 288

COLOR-LIGHT SIGNALS

180. Long-range Type 291

181. Medium-range Outdoor Type 293

182. Short-range Subway and Tunnel Type 297

POSITION-LIGHT SIGNALS

183. Long-range 299

184. Short-range or Dwarf 301

CHAPTER XVI
HIGHWAY CROSSING SIGNALS

185. General 302

186. Highway Crossing Signals 302

187. Highway Crossing Signal Circuits 305

188. Interlocking Relay .306

189. Hoeschen Bell System .... .308

190. AGA Highway Danger Signals 315

APPENDIX A

Rules Governing the Construction, Maintenance and Operation of

Interlocking Plants . 318-324

APPENDIX B
PART I

Signal Aspects 325-327

PART II
Symbols Recommended by the Railway Signal Association .... 328-340

APPENDIX C

A Definition of Terms Used in Railway Signaling 341-362

Index. 363






RAILWAY SIGNALING



CHAPTER 1
PRELIMINARY

1. Introductory. ^-Practically the only purpose a railroad has
is to give train service to the public and its industries; and
whatever will facilitate and expedite train movements to the best
advantage to serve this purpose with a reasonable expenditure of
capital will work to the best interests of the public generally.
As the number of trains increases and their speed, weight, and
length grow greater in the effort to handle the continually increas-
ing volume of traffic, the demands for safe and efficient methods
of train operation become more urgent. A great many factors
enter into the success of railroad transportation, among which
are the motive power and train equipment, the track and road-
way, the signal systems and methods of despatching trains, and
the personnel of the employees from the office boy to the manager.
This text deals only with signaling; and the reader should bear
in mind that signaling is a means to an end and not the end
itself.

2. History. An early history of railway signaling in America
written by Mr. J. A. Anderson and published in the March 5, 1909
issue of the Railway Age Gazette and reprinted in the 1909 Volume
of the Proceedings of the Railway Signal Association^ gave 1870
as the date for the first interlocking plant and 1863 as the date^
for the first block system. The interlocking plalit was installed
at Trenton, N. J., on the line of the United New Jersey Canal
and Railroad Companies, afterwards leased by the Pennsylvania
Railroad Company. The machine was built by Saxby and
Farmer of London after the same pattern as those they had built
and installed on lines in England. It was built principally as
an experiment, and from this humble beginning the interlocking
plant has been installed wherever important railroad crossings
and terminals have been established.

1



2 RAILWAY SIGNALING



The block system was introduced by the same company on the
line between New Brunswick and Philadelphia. A form of block
signaling had been proposed in England as early as 1842, but its
adoption in that country generally was very limited for a number
of years afterwards. The system established in America gave
positive indications by means of signals, and went a long way in
eliminating many of the difficulties involved in the older foreign
systems.

In the early days practically all of the signal appliances were
of a mechanical type, more or less simple in construction, and
did not require men especially trained for their maintenance
and operation. Improvements were made from time to time to
keep pace with the demands of transportation. The public
saw in signaling possibilities for greater safety; the railroads saw
opportunities for both safety and efficiency in operation. Later,
electricity was applied to solve the signal problems, and it became
a potent factor in the growth of the signal industry. More and
more was it utilized to replace the human element in signal
operation. As the systems grew, organizations grew with them.
As the equipment became more complicated, there came the
demand for specialists, men who were better trained, and who
could give all their time and attention to this particular kind of
work. Power interlocking was introduced and the track circuit
became well established. Gradually a reliable system has thus
been developed to meet the needs of the situation. Interlocking
appliances have been made better and automatic block systems
perfected until accidents rarely occur on account of signal
failures. The service has been so improved that many roads
have been able largely to eliminate the train order as a factor in
despatching trains.

3. Organization. The field of signal engineering is a distinct
one and embraces construction, installation, operation and
maintenance of railway signals. The equipment is practically
all made by signal manufacturers and is bought by the railroads
at a unit price or on a contract basis. The companies that make
the equipment may also install it, or the railroad may take the
equipment when it is delivered and install it with its own con-
struction forces. In nearly all cases the maintenance is handled
by railroad forces.

The general type of organization that prevails on a road will
determine, in a measure at least, the particular organization of



PRELIMINARY 3

the signal department. In the departmental system, the signal
engineer reports to the chief engineer and has charge of all the
work of the signal department. He makes requisitions for new
equipment, has charge of all materials and supplies on hand and
directs the work of the organization. In the divisional system,
the signal engineer reports to the chief engineer as before and has
immediate charge of standards and construction. The divisional
maintenance is in charge of the signal supervisor who reports
directly to the division superintendent or division engineer. In
this connection he is assisted in an advisory way by the signal
engineer. The following article written by Mr. A. G. Shaver
and published in the September, 1917, issue of the Signal Engineer
states some of the requirements for success as a signal engineer
and outlines a typical signal department organization: 1

. "Four qualifications are indispensable in every man that he may be
a good signal engineer; he must have had experience in railway signal-
ing; he must have a technical education; he must be a good executive,
and he must have a general knowledge of railroading. Any signal
engineer who does not have an intimate knowledge of signaling, such as
one gets from actual service as laborer, skilled workman, foreman or
maintainer, is not only greatly handicapped, but is more or less inefficient
to his company. The technical education need not be that acquired by
a course in college, though that is an advantage; it must include a
very complete knowledge of the general principles of electricity, an
understanding of mechanics and a familiarity with those features of
civil engineering concerned in railroad construction. Since the job of
signal engineer on most railroads carries with it a command over men,
executive ability is necessary for effective results. In railroading a
knowledge of construction, maintenance and operation is needed. The
construction of the railroad and the signaling must harmonize and be
maintained and operated together; it is particularly necessary to know
how trains are run and what the facilities must be for trains to be
operated to the best advantage.

"Signal departments vary considerably in make-up and jurisdiction,
having often been gradually built up from some old arbitrarily established
basis and having to meet conditions peculiar to the railroad itself.
There are, doubtless, few signal department organizations entirely
satisfactory to the signal engineer in charge.

"An example of a suitable signal department organization for a large
road is shown by the diagram Fig. 1. The assistant signal engineer,
the general inspector, the superintendent of signal construction, the chief

1 Page 276.



4 RAILWAY SIGNALING

draftsman and the chief clerk all report to the signal engineer. The
assistant signal engineer is in authority next to the signal engineer and
has charge of all matters pertaining to maintenance and operation and
the preparation of standards and specifications. The general signal
inspector has supervision over all inspections, investigations, tests,
experiments, educational matters and the signal shop. The superin-
tendent of signal construction has charge of all work of construction,
reconstruction and changes. The chief draftsman has the preparation
of estimates and drawings, the designing of circuits and apparatus and,
under the assistant signal engineer, the making of standards and speci-
fications. The chief clerk has authority over the force and business
of the office, including accounts, statistics, reports, payrolls, etc. The



| Signal Engineer |



Clerk |
|






Asst. Signal
Engineer




Isupt. Signal
Construction


Force |


General
Inspector


Chief | 1 Construction
1 Draftsman | | Foremen





| Superintendent |



| Signal Shop |



Educational
Work



Signal
Supervisor'



Drafting
Force



Construction
Forces



Maintenance
Forces



FIG. 1. A typical signal department organization. (Railway Signal Engineer.)



signal supervisor reports to the superintendent in all matters pertaining
to the maintenance and operation of signals and to the assistant signal
engineer on technical matters, special reports, special requisitions and
those things not covered by standards and approved practices; he is
appointed by the superintendent on approval of the signal engineer.
The signal engineer gives to the superintendent general and special in-
structions concerning maintenance and operation of signals, confers
with him regarding new construction proposed and authorized and as-
sists to get efficient results from the signaling in service.

"On a small railroad this organization may be varied to suit condi-
tions. Ordinarily the signal engineer would have direct authority over
the maintenance and operation of signals as well as construction and
other matters, and his organization might be curtailed as to the number
and assignment of subordinates. Indeed, a railroad may be so small,
as to the amount of signaling it has, as not to need a signal department



PRELIMINARY 5

at all. The care of its signal work could be given over to some existing
department having work of a like nature and expert service hired as
required."

4. Rules for Signal Supervisors and Signal Foremen. In

order to establish a high grade of uniform practice among signal
supervisors and their foremen, the following rules were prepared
and written in the Manual of the American Railway Engineering
Association: 1

RULES GOVERNING SIGNAL SUPERVISORS

1. Signal Supervisors shall report to and receive instructions from the
(Title)

2. They shall be responsible for the safe condition and proper maintenance
of signals and interlocking plants. They must make temporary repairs
of such defects as may endanger or delay the movement of trains, and
promptly report defective conditions to the !T!*!.?1

3. They must make frequent inspections of signals and interlocking plants
and have necessary repairs made as promptly as conditions require. They
must see that all failures of signals and interlocking plants are promptly
investigated and report made on Form No

4. They shall, as necessary, employ men for carrying out the duties for
which they are responsible.

5. They must know that foremen are familiar with the operating rules
in regard to tram signals and flagging, arid that they fully understand and
comply with them.

6. They must, in case of damage to signals or interlocking, pronnotly as-
semble forces, tools and materials, and make necessary repairs.

7. They shall investigate and report on accidents which may be attri-
butable to defects in, or result in damage to, the signal apparatus.

8. They shall conform to the prescribed standards and plans in the execu-
tion of work under their charge.

9. They must know that foremen are supplied with tools and materials
necessary for the efficient performance of their duties, and see that these
are properly used and cared for.

10. They must not, except by proper authority, permit experimental
trials of appliances or devices, nor give out information of the results of
any trial.

11. They shall keep themselves informed in regard to all work performed
in their districts by contractors, or others who do not come under their
charge, see that nothing is done by them that will interfere with the safe
operation of signals, and report promptly to the (.T^?.)

if the work is not done in accordance with the prescribed standards.


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Online LibraryEverett Edgar KingRailway signaling → online text (page 1 of 23)