US904834A - Electric railway signaling system. - Google Patents

Electric railway signaling system. Download PDF

Info

Publication number
US904834A
US904834A US40561407A US1907405614A US904834A US 904834 A US904834 A US 904834A US 40561407 A US40561407 A US 40561407A US 1907405614 A US1907405614 A US 1907405614A US 904834 A US904834 A US 904834A
Authority
US
United States
Prior art keywords
conductor
conductors
train
track
rails
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US40561407A
Inventor
Yorke Burgess
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US40561407A priority Critical patent/US904834A/en
Application granted granted Critical
Publication of US904834A publication Critical patent/US904834A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L3/00Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal
    • B61L3/16Continuous control along the route
    • B61L3/18Continuous control along the route using electric current passing between devices along the route and devices on the vehicle or train
    • B61L3/185Continuous control along the route using electric current passing between devices along the route and devices on the vehicle or train using separate conductors

Definitions

  • Wihmaazo YORKE BURGESS OF WASHINGTON, DISTRICT OF COLUMBIA.
  • a visual signal such as a light
  • the electric connections extending through the rails and including switches, draw-bridges and other parts of the track structure so that in the event of the continuity of the track being broken or a'switchbeing misplaced or a draw-brid e being opened, the signal will no longer be displayed, thus indicating that the circuit is broken so that the engineer is warned to stop or proceed with caution.
  • the invention provides means whereby the approach of two trains within dangerous proximity will cause warning signals to be displayed in the cabs of both engines or on other portions of the trains, while should no attention be paid to the warning signals by the enginemen. the apparatus will be caused to o crate to automatically stop the trains be ore a collision is possible.
  • two-like series of conductors eitherin the form of trolley wires or third rails along the line of the track, and these conductors cross each other atintervals throughout the length of the system so that traveling contacts carried by the train will each make contact with the same conductor or section thereof, in alternate order, the return circuit being through the track rail or rails.
  • each train is provided with two sources of electric energy which may he in the form of two small dynamos connected in opposite order to the respective contacts.
  • the invention likewise provides means whereby the sectional conductors are made continuous to telephonic currents, although operatively discontinuous to straight currents supplied by the dynamics or other like source of electric energy, so that a train despatcher may have full-control of all of the trains on the line through telephonic communication.
  • Figure 1 is a diagrammatic representation of the cab circuits of two trains and the track circuits arranged in accordance with the present invention.
  • Fig. 2 is a diagrammatic representation of the system as arranged at the crossing of two lines of railroad.
  • a track 1 of the ordinary type the rails of which, except at certain points, are to be suitably bonded so that the track rails become practically con-- tinuous COI'ldHCtOl'S.
  • Extending along the line of way are two lengths of the conductors alternate with each other in position so that the line conductors are made up of two sectional conductors alternately disposed with reference o each other throughout the length of the s stem.
  • each -conductor The contiguous ends of the sections of each -conductor are connected through condensers 5, for a purpose which will presently appear.
  • mounted upon each cab are two dynamos 6, 7, each capable of impressing upon 'the line about fifty volts.
  • One brush say that on the positive side of the dynamo 6; is connected by a conductor 8 to a contact terminal 9, and another conductor 10 is also connected to the same brush and ultimately connects to still another conductor 11 leading throughout the length of the train by means of suitable couplings,
  • the conductor 19 is likewise connected by another conductor 21 througha normally open switch 22 to the conductor 8.
  • Each magnet 14, 15 and 16 controls an armature 23 in a branch line 24 including a signal mp 25.
  • the armature terminates in a contact 26, in the path of which is another contact 27 connected by'a conductor 28 to the conductor 11.
  • Branched off from the armature 23 of the relay magnet 16 is another conductor 29 including a solenoid 30 and a switch 31 and leads to the conductor 11.
  • the conductor 8 of the dynamo 7 is connected to''- two terminals 31 and 32 on each side of the terminal 9.
  • the terminals 9, 31 and 32 are controlled by a pole-changing switch 33, the two arms of which are connected by conductors 34 and 35 to contact shoes 36 and 37 respectively, the contact shoe 36 being arranged .to make contact with the like halves of the tions of the conductors 3 and 4.
  • fuses 38 In each conductor 34 and 30 are included fuses 38. Branched 01f from the conductors 34 and 35. are other conductors 39, 40, leading to a telephone set 41, and'included in'the conductor 40 is a condenser 42.
  • the intermediate point of each section of the conductors 3 and 4 is connected by anotherconductor 43 through resistances 44 branched to contiguous ends-of the block section ofeach of the rails 1.
  • Fig. 1 In Fig. 1 are shown two railway switches 45, 46.
  • the switch 45 is presumed to be of the type which is normally in a position to maintain the main line rails 1 in condition for traffic and to be only occasionally moved to connect the main line to a siding, while the switch 46 is presumed to be normally in position to direct a train from the main line to a branch line or siding.
  • c 7 In Fig. 1 are shown two railway switches 45, 46.
  • the switch 45 is presumed to be of the type which is normally in a position to maintain the main line rails 1 in condition for traffic and to be only occasionally moved to connect the main line to a siding, while the switch 46 is presumed to be normally in position to direct a train from the main line to a branch line or siding.
  • one of the track rails 1 is connected by a branch conductor 47 to a contact terminal 48, and
  • another contact terminal 49 adjacent to the contact terminal 48 is connected by a conductor 60 to the conductor 3, or sometimes to the conductor 4, while one of the switch points 50 carries a bridging block 51 adapted to open the circuit between the terminals 48 and 49 when the switch is in the position to allow traii'ic upon the main line, but when a switch is moved to a position to connect the main line to the siding, then the bridging block 51 is moved between the contacts 48 and 49 and the circuit is closed.
  • the switch 46 has one of its points carrying a bridge block 51 in the path of which are two spaced contact terminals 52, one connected to the traflic rails 1 and the other by a conductor 53, to a sectionof the conductor 4 or under some circumstances to asection of the conductor 3.
  • terminals 56 -:-ne connected to the track 1 and the other 5 a conductor 57 to the conductor '4.
  • the conductors 3 and 4 are coupled at the crossing points upon the train, but because a turbine is a small and compact power means it consti tutes a convenient type of drive for the dy-,
  • generators may be of the shunt wound type and ma develop from onequarter to one-half liorse power at fifty volts. If the generator 6 has the positive terminal connected to one-of the shoes, say the shoe 37, then the generator 7 will have its negative terminal connected to the shoe ditions prevail.
  • the relays 14 are so Wound as to be actuated by a smaller current than the output of each dynamo,- and the current is kept down by the resistances 44 under normal conditions.
  • the current will flow from the dynamo to the trolley wire or rails, hence to the conductor 43 and resistances 44 to the track and back through the conductor 19.
  • the lamp 25 controlled by the relay 14 therefore glows continuously so long as these con-
  • the switch 46 should be displaced or the draw-bridge 54 should open, then the resistance 44 is cut out and the full force of fifty volts will flow through the circuit.
  • the relay 15 which is wound to respond only to such increased current, will be energized and the corresponding lamp will glow, this being a caution-indicating lamp. The engineman will then proceed with caution until the switch or bridge is reset and the clear light will again be in evidence.
  • the dynamo 58 will energize the conductors close to a terminal and thus prevent the trains from approaching said terminal except under the desired restrictions.
  • the switches 22 are normally open and are closed only when one or the other of the dynamos fails to work.
  • the switch 33 is for the purpose of changing the polar relations of the dynamos with the shoes 36 and 37.
  • the conductors 3 and 4 are therefore continuous conductors with respect to the telephonic structure but are sectional or discontinuous conductors with relation to the signal apparatus:
  • the voltage employed in the system may be greater or less than fifty volts, which latter is only illustrative.
  • the conductors 43 are connected to the contiguous ends of the rails at the terminals of the block stations or lengths of rails which form a continuous circuit, by the resistances 44 which are branched off from the conductor to both rails of the track on each side of the break in the continuity thereof. There is thus at all times two resistances in multiple-arc with the conductor 43, and these multiple resistances are so adjusted that under normal conditions the current flowing through them is sufficient to energize the relay 14.
  • a source of electric energy a number of signaling means on each train, each individual signaling means being responsive to a different strength of electric current, a pair of traveling contacts arranged on each train, means for connecting either contact to the same polar terminal of the source of current, and a pair of sectional conductors arranged along the line of way in the paths of the contacts,'said conductors crossing each other at intervals to present portions of their lengths alternately on oppositesides to be engaged by the contacts in alternation.
  • line conductors formed in sections. each section having portions in different planes and the sections alternating, a source of energy and a signaling means on each train, a pair I of contacts carried by each train and arranged to engage one with each of the sections of the conductor, train conductors connecting said contacts to the opposite poles of the source of energy, means connecting one of said current conductors to the local wiring system, a return conductor, and a traveling contact connected to the wiring system of each train and engaging said return conductor.
  • a source of electric energy upon the train a pair of contacts upon the train, line conductors arranged alternately in the path of each contact, a constantly displayed signal upon the train operative under normal circuit conditions, another signal upon the train 'responsive to increased current in the circuit, and still another signal apparatus responsive to a still greater increase in the current in the circuit.
  • a source of constant current electric energy a signal means 011 each train, sectional conductors along the line of way, contacts ar .ranged to engage the sectional conductors and a signalingmeans on each train, a pair of sectional conductors having the sections crossing each other at intervals to present portions of their lengths alternatively on opposite sides, a pair of traveling contacts arranged on each train to engage said conductors in alternation, a telephone apparatus upon each train, and condensers connecting the ends of the sections of each conductor to render the conductors continuous to telephone currents.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Train Traffic Observation, Control, And Security (AREA)

Description

Y. BURGESS.
ELECTRIC RAILWAY SIGNALING SYSTEM.
. APPLICATION FILED DEU.'I,190'I. 9Q4,834 atented Nov. 24, 1908. 2 SHEETSSHBET 1. 475} Mi tneaaeo f Y. BURGESS. v
ELECTRIC RAILWAY SIGNALING SYSTEM.
APPLICATION FILED DEC. 7. 1907.
Patented Nov. 24, 1908.
2 SHEETS-SHEET 2.
Wihmaazo YORKE BURGESS, OF WASHINGTON, DISTRICT OF COLUMBIA.
ELECTRIC RAILWAY SIGNALING SYSTEM.
Specification ofLetters Patent.
Patented Nov. 24, 1908.
Application filed December '1, 1907. semi No. 405,614.
\ To all whom it may concern:
Be it known that I, YORKE BUnonss, a cit-izen of the United States. residing at \Vashtrain standing upon a track or running inv either-direction is notified of the approach of other trains on the same track in either direction.
In accordance with the present invention there is at all times displayed a visual signal, such as a light, which will indicate that the system is inworking order, the electric connections extending through the rails and including switches, draw-bridges and other parts of the track structure so that in the event of the continuity of the track being broken or a'switchbeing misplaced or a draw-brid e being opened, the signal will no longer be displayed, thus indicating that the circuit is broken so that the engineer is warned to stop or proceed with caution.
Furthermore, the invention provides means whereby the approach of two trains within dangerous proximity will cause warning signals to be displayed in the cabs of both engines or on other portions of the trains, while should no attention be paid to the warning signals by the enginemen. the apparatus will be caused to o crate to automatically stop the trains be ore a collision is possible.
For carrying out the purposes of the present invention there is provided two-like series of conductors 'eitherin the form of trolley wires or third rails along the line of the track, and these conductors cross each other atintervals throughout the length of the system so that traveling contacts carried by the train will each make contact with the same conductor or section thereof, in alternate order, the return circuit being through the track rail or rails.
In order to provide against certaincontingencies that may arise, each train is provided with two sources of electric energy which may he in the form of two small dynamos connected in opposite order to the respective contacts. p
In.accordance with the present invention there is further provided a continuous circuit throughout the length or" the train forniing an extension of the cab circuits so that the 'engineman will be instantly notified in case the train breaks by the failure of the permanent signal to be longer displayed.
In addition to the foregoing the invention likewise provides means whereby the sectional conductors are made continuous to telephonic currents, although operatively discontinuous to straight currents supplied by the dynamics or other like source of electric energy, so that a train despatcher may have full-control of all of the trains on the line through telephonic communication.
' The invention will be best understood by consideration of the following detail description taken in connection with the accompanying drawings forming part of this specification, in which drawings,
Figure 1 is a diagrammatic representation of the cab circuits of two trains and the track circuits arranged in accordance with the present invention. Fig. 2 is a diagrammatic representation of the system as arranged at the crossing of two lines of railroad. Referring to the drawings, and more especially to Fig. 1, there is shown a track 1 of the ordinary type the rails of which, except at certain points, are to be suitably bonded so that the track rails become practically con-- tinuous COI'ldHCtOl'S.
Extending along the line of way are two lengths of the conductors alternate with each other in position so that the line conductors are made up of two sectional conductors alternately disposed with reference o each other throughout the length of the s stem.
The contiguous ends of the sections of each -conductor are connected through condensers 5, for a purpose which will presently appear. Mounted upon each cab are two dynamos 6, 7, each capable of impressing upon 'the line about fifty volts.
in this conductor One brush, say that on the positive side of the dynamo 6; is connected by a conductor 8 to a contact terminal 9, and another conductor 10 is also connected to the same brush and ultimately connects to still another conductor 11 leading throughout the length of the train by means of suitable couplings,
conventionally indicated at 12, and returning three relay magnets 14, 15 and 16 in multiple arc branches of this conductor, while the other sides of these three magnets are connected in multiple arc to another conductor 17 leading through a switch 18 to a conductor 1.9 which may be connected through the metal parts of the locomotive to the rails, and this IS conventionally indicated by the wheel 20. The magnets 14, 15 and 16 are wound to respond respectively to different voltages.
The conductor 19 is likewise connected by another conductor 21 througha normally open switch 22 to the conductor 8.
Each magnet 14, 15 and 16 controls an armature 23 in a branch line 24 including a signal mp 25. The armature terminates in a contact 26, in the path of which is another contact 27 connected by'a conductor 28 to the conductor 11. Branched off from the armature 23 of the relay magnet 16 is another conductor 29 including a solenoid 30 and a switch 31 and leads to the conductor 11.
Though not so shown in the drawings it is to be understood that this solenoid 30 is connected to the train-controlling mechanactly like that which the dynamo 6 feeds,
and therefore is indicated by the same reference numerals and need not be particularly described further than that the conductor 8 of the dynamo 7 is connected to''- two terminals 31 and 32 on each side of the terminal 9.
The terminals 9, 31 and 32 are controlled by a pole-changing switch 33, the two arms of which are connected by conductors 34 and 35 to contact shoes 36 and 37 respectively, the contact shoe 36 being arranged .to make contact with the like halves of the tions of the conductors 3 and 4. In each conductor 34 and 30 are included fuses 38. Branched 01f from the conductors 34 and 35. are other conductors 39, 40, leading to a telephone set 41, and'included in'the conductor 40 is a condenser 42. The intermediate point of each section of the conductors 3 and 4 is connected by anotherconductor 43 through resistances 44 branched to contiguous ends-of the block section ofeach of the rails 1.
In Fig. 1 are shown two railway switches 45, 46. The switch 45 is presumed to be of the type which is normally in a position to maintain the main line rails 1 in condition for traffic and to be only occasionally moved to connect the main line to a siding, while the switch 46 is presumed to be normally in position to direct a train from the main line to a branch line or siding. c 7
In the case of the switch 45 one of the track rails 1 is connected by a branch conductor 47 to a contact terminal 48, and
another contact terminal 49 adjacent to the contact terminal 48 is connected by a conductor 60 to the conductor 3, or sometimes to the conductor 4, while one of the switch points 50 carries a bridging block 51 adapted to open the circuit between the terminals 48 and 49 when the switch is in the position to allow traii'ic upon the main line, but when a switch is moved to a position to connect the main line to the siding, then the bridging block 51 is moved between the contacts 48 and 49 and the circuit is closed.
The switch 46 has one of its points carrying a bridge block 51 in the path of which are two spaced contact terminals 52, one connected to the traflic rails 1 and the other by a conductor 53, to a sectionof the conductor 4 or under some circumstances to asection of the conductor 3.
In the case of a draw-bridge, such as indicated at 54, again there is a bridge block 55 carried by the draw-bridge structure, and
a the path of this block are terminals 56 -:-ne connected to the track 1 and the other 5 a conductor 57 to the conductor '4. In the case of a railroad crossing'the conductors 3 and 4 are coupled at the crossing points upon the train, but because a turbine is a small and compact power means it consti tutes a convenient type of drive for the dy-,
namo. These generators may be of the shunt wound type and ma develop from onequarter to one-half liorse power at fifty volts. If the generator 6 has the positive terminal connected to one-of the shoes, say the shoe 37, then the generator 7 will have its negative terminal connected to the shoe ditions prevail.
36 and the dynamos of the several trains are so connected that when the trains are brought into the danger zone and are approaching each other either in opposite directions or the same directions, then, one dynamo will be in series with the other dynanm and so thevoltage'is au mented and the current output is correspondingly increased.
The relays 14 are so Wound as to be actuated by a smaller current than the output of each dynamo,- and the current is kept down by the resistances 44 under normal conditions. Let it be assumed that the train is upon a clear section of track, then the current will flow from the dynamo to the trolley wire or rails, hence to the conductor 43 and resistances 44 to the track and back through the conductor 19. Under these conditions the lamp 25 controlled by the relay 14 therefore glows continuously so long as these con- Suppose, now, the switch 46 should be displaced or the draw-bridge 54 should open, then the resistance 44 is cut out and the full force of fifty volts will flow through the circuit. Under these conditions the relay 15 which is wound to respond only to such increased current, will be energized and the corresponding lamp will glow, this being a caution-indicating lamp. The engineman will then proceed with caution until the switch or bridge is reset and the clear light will again be in evidence.
' Suppose, now, that one train is approaching another running in the same direction or that two trains are approaching from opposite directions and come within dangerous proximity. Under these conditions the dynamos of the two trains are connected up in series and there is developed a voltage of one hundred, and this is sufficient to energize the relay 16 wound for such voltage, which will cause the corresponding lamp,.a danger lamp, to glow and'will likewise energize the solenoid 30, thus shutting off steam and applying brakes in the customary manner employed with railway signals of-this character, or the air brakes alone may be operated? The sections of the conductors 3 and 4 may be of course of any length desired, depending upon trafiic conditions.
The dynamo 58 will energize the conductors close to a terminal and thus prevent the trains from approaching said terminal except under the desired restrictions.
In the structure shown in the diagram of Fig. 2, two trains cannot approach a crossing where the tracks intersect close enough to cause a collision since at this point a train on one track .will control the train on't-he 60.
other track. I
The switches 22 are normally open and are closed only when one or the other of the dynamos fails to work. The switch 33 is for the purpose of changing the polar relations of the dynamos with the shoes 36 and 37.
The conductors 3 and 4 are therefore continuous conductors with respect to the telephonic structure but are sectional or discontinuous conductors with relation to the signal apparatus: The voltage employed in the system may be greater or less than fifty volts, which latter is only illustrative.
' It is to be observed that the conductors 43 are connected to the contiguous ends of the rails at the terminals of the block stations or lengths of rails which form a continuous circuit, by the resistances 44 which are branched off from the conductor to both rails of the track on each side of the break in the continuity thereof. There is thus at all times two resistances in multiple-arc with the conductor 43, and these multiple resistances are so adjusted that under normal conditions the current flowing through them is sufficient to energize the relay 14. Should, however, a fault occur in either rail, as for instance, the breakage of the rail or the breakage of the bond between the rail ends or possibly the malicious or accidental re moval of the rail, then one of the resistances is cut out, which means that the total resistance at this point is therefore doubled and the several electrical conditions are such that this doubling of the resistance-will cut down the currentsufficiently to reduce the pull of the magnet 14 to such an extent as to cause the break of the circuit between the terminals '26 and 27. This will occur even though only one rail of the track be disturbed or with. a fault occurring only in the one rail and is i'mportantbecause a fault in one rail maybe as dangerous to traffic as a fault in two rails. i
What is claimed is 1. In an electric railway signaling system, a source of electric energy, a number of signaling means on each train, each individual signaling means being responsive to a different strength of electric current, a pair of traveling contacts arranged on each train, means for connecting either contact to the same polar terminal of the source of current, and a pair of sectional conductors arranged along the line of way in the paths of the contacts,'said conductors crossing each other at intervals to present portions of their lengths alternately on oppositesides to be engaged by the contacts in alternation.
2. In electric railway signaling systems, line conductors formed in sections. each section having portions in different planes and the sections alternating, a source of energy and a signaling means on each train, a pair I of contacts carried by each train and arranged to engage one with each of the sections of the conductor, train conductors connecting said contacts to the opposite poles of the source of energy, means connecting one of said current conductors to the local wiring system, a return conductor, and a traveling contact connected to the wiring system of each train and engaging said return conductor.
3. In an electric railway signal system, two sources of electric energy on each train, a pair of traveling contacts on each train, line conductors each alternately in the path of each of the traveling contacts, means for coupling up the contacts each to one ofthe sources of current, and means for shunting the contacts around either or both of said sources of energy.
4. In electric railway signaling systems, a source of electric energy upon the train, a pair of contacts upon the train, line conductors arranged alternately in the path of each contact, a constantly displayed signal upon the train operative under normal circuit conditions, another signal upon the train 'responsive to increased current in the circuit, and still another signal apparatus responsive to a still greater increase in the current in the circuit.
5. In an electric railway signal system, a source of constant current electric energy, a signal means 011 each train, sectional conductors along the line of way, contacts ar .ranged to engage the sectional conductors and a signalingmeans on each train, a pair of sectional conductors having the sections crossing each other at intervals to present portions of their lengths alternatively on opposite sides, a pair of traveling contacts arranged on each train to engage said conductors in alternation, a telephone apparatus upon each train, and condensers connecting the ends of the sections of each conductor to render the conductors continuous to telephone currents. g In testimony that claim the foregoing as my own, I have hereto afiixed my signature in the presence of two witnesses.
YORKE BURGESS.
Witnesses:
JAS.'M. WALKER, F. T. CHAPMAN.
US40561407A 1907-12-07 1907-12-07 Electric railway signaling system. Expired - Lifetime US904834A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US40561407A US904834A (en) 1907-12-07 1907-12-07 Electric railway signaling system.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US40561407A US904834A (en) 1907-12-07 1907-12-07 Electric railway signaling system.

Publications (1)

Publication Number Publication Date
US904834A true US904834A (en) 1908-11-24

Family

ID=2973269

Family Applications (1)

Application Number Title Priority Date Filing Date
US40561407A Expired - Lifetime US904834A (en) 1907-12-07 1907-12-07 Electric railway signaling system.

Country Status (1)

Country Link
US (1) US904834A (en)

Similar Documents

Publication Publication Date Title
US904834A (en) Electric railway signaling system.
US840428A (en) Electrical signaling system.
US1190247A (en) Railway signaling system.
US759543A (en) Electric railway-signal.
US926687A (en) Electric railway signal system.
US1177842A (en) Electric signaling system.
US819322A (en) Electric signaling.
US889561A (en) Signal system for railways.
US558565A (en) Railway-signal
US441703A (en) eiggs
US1162890A (en) System of train control.
US774618A (en) Electrically-operated block-signaling apparatus.
US562318A (en) Railway-signal
US1264720A (en) Railway signaling system.
US1163190A (en) Railway-signal.
US1385295A (en) Railway signaling
US786209A (en) Electric railway signaling system.
US492770A (en) Railroad-crossing
US1232441A (en) Breakdown-detector for rail-joint insulation.
US1187473A (en) Railway signaling system.
US884158A (en) System of automatic block-signaling for electric railways.
US1263371A (en) Railroad block-signaling means.
US1317405A (en) Planoqraph co
US1137705A (en) Automatic-block signaling system for electric railways.
US1110326A (en) Railway safety appliance.