US2229736A

US2229736A - Centralized traffic controlling system for railroads

Info

Publication number: US2229736A
Application number: US266802A
Authority: US
Inventors: William D Hailes; Reginald F Albrighton
Original assignee: General Railway Signal Co
Current assignee: SPX Corp
Priority date: 1939-04-08
Filing date: 1939-04-08
Publication date: 1941-01-28
Anticipated expiration: 1958-01-28

Description

Jan. 28, 1941. w. D. HAlLES EIAL CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed April 8, 1939 4 Sheets-Sheet 1 INVENTOR5 W. D. Hai les and PFAIbri BY M r I 1 I THEIR ATTORNEY w. D. HAILES ETAL ,735

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed April 8, 1939 v 4 Sheets-Sheet 2 INVENTORS WD IJaiIes and RFAIbrighTon THEIR ATTORNEY J ll l 3: :9 as c 9 IIII v 5 3 0 U M .w .v H l 22L r 1.. 25 zo 4 Sheets-Sheet 3 Mon E U E3 @952 v5 E $5 LU M THEIR ATTORNEY l wa m n N8 N8 53 INVENTORS WDHaiLs and PEAIbri W. D. HAILES ETAL Jan. 28, 1941.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR HAILROADS Filed April 8, 1939 hem uOOO M llr I I 1941- w. D. HAILES EI'AL 2,229,736

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS 4 Sheets-Shet 4 Filed April 8, 19:59

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S i ||1 S g3 cou .FA brighTon Y mD mdMR N 0 Ed. W V H m a. E HY m D W Patented Jan. 28, 1 941 UNITED STATES FATEN'E' @FFWE CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Application April 8, 1939, Serial No. 266,892 9 Claims. (c1. 246-) This invention relates to centralized traffic controlling systems for railroads, and it more particularly pertains to the adaptation of a code type communication system to a block signalling 5 system.

In a code type centralized traffic controlling system for railroads, an operator at a control office can govern the various remotely located track switches and signals in the track layout for which the system is provided. Those track switches and signals relatively close together and their control means responsive to controls transmitted from the control office, constitute a field station. The controls are transmitted from the control ofiice by code to the various field stations to the position of the track switches, the occupancy of the various track sections and the clear or stop indication of the signals, are transmitted from the various field stations to the control over a line circuit, and similarly, indications as oflice.

The safety of the system with respect to the operation of the track switches and signals is largely dependent upon the automatic block signal circuits provided in the field, as shown, for example, in the patent to S. N. Wight, Patent No. 2,082,436, dated June 1, 1937. The circuits in such a system of block signalling provide that opposing signals for the main track at opposite ends of a passing siding cannot be clear at the same time, even with the associated track sections unoccupied by approaching trains.

There is no provision made, however, in some centralized trafiic controlling systems, for an interlock between the opposing signals for the opposite ends of a passing siding for train movements into that siding, as such signals display only low speed indications. Although it is not a dangerous condition to contemporaneously clear opposing low speed signals for train movements into the same passing siding, it is a condition that could, in practice, cause considerable delay if such opposing signals. were inadvertently cleared by an operator.

45 In accordance with the present invention, a control machine is located in a control ofiice, and it is provided with a control lever for the track switch at each end of a passing siding, and a control lever for the signals governing traffic in 50 either direction over each track switch. Each switch control lever has a normal and a reverse position, and each signal control lever has a center-at-stop position, a right-hand position for clearing a signal for one direction of trafiic, and

55 a left-hand position for clearing a signal for the opposite direction of trafiic. The usual mode of operation on the part of an operator is to maintain the position of the control levers in correspondence with the position or condition of their associated devices at the field stations, until he 5 has an occasion to cause a change in the position of such devices.

An object of this invention is to provide an economical means for interlocking opposing signals for governing traffic into a passing siding, 10 to prevent an operator from inadvertently clearing opposing signals contemporaneously for train movements into that track from opposite directions. Such an interlock is provided on the control machine in the control oiiice by circuit selec- 15 tions on the switch and signal levers in such a manner that the communication system at the control oifice can be set into operation for the transmission of controls to the field stations only if the position of the control levers for the devices 20 at that particular field station is other than that position corresponding to the clearing of opposing signals for governing trafiic into the passing siding. Such an interlock is usable with a code type communication system, because it is re- 25 quired more as a matter of facility than as a matter of safety. Any code type centralized traffic controlling system, such, for example, as the system shown in the patent to Judge et al., Patent No. 2,082,544, dated June 1, 1937, can be used 30 to connect the control machine with the field apparatus.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference is made to the accompanying drawings which show one embodiment of the present invention, 40

in which parts of a similar character are designated by similar letter reference characters which are usually made distinctive by preceding numerals, and'in which Fig. 1 illustrates the part of a control office transmitter associated with the starting of a cycle of operation of a'code type communication system, and the selection of the'various codes to be transmitted;

Fig. 2 illustrates the part of a control ofiice transmitter associated with stepping and impulsing of the line circuit in a code type communication system throughout the various cycles of operation; and

Figs. 3A and 3B, when placed end-to-end, illustrate the track layout for the particular embodiment chosen for the disclosure of the present invention, together with switch and signal control relays for such track layout.

In order to simplify the disclosure of the present invention, the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed. The drawings have been made more for the purpose .of facilitating the disclosure of the invention as to the principles and mode of operation of the system, than for the purpose of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, certain parts of the system well known to those familiar with the art have been illustrated in an abbreviated form by dotted lines, and the various relays and their contacts, together with terminals for batteries or other sources of electric current, are illustrated in a conventional manner instead of showing all of the details associated with such devices.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current, and the circuits which those symbols are used always have current flowing in the same direction. The symbols (B+) and (B-) indicate connections to the opposite terminals of a suitable battery or other direct current source which has a center tap (CN). If alternating current is used, the symbols and are to be considered as instantaneous relative polarities.

Inasmuch as the communication system used in thisembodiment of the present invention is substantially as shown and described in detail in the above-mentioned Judge: et al. Patent No. 2,082,544, only a general description of that communication system is included in the description of the present invention as reference can be made to that patent for detailed description of such system.

With reference to Figs. 3A and 3B, the track layout for this embodiment of the present invention is illustrated as having a passing siding connected to a main track by power operated track switches BTS and 8T8. Signals 2A and 2B are provided for governing east-bound trafiic to the right over track switch STS, and signals 4A and 4B are provided for governing eastbound trafiic to the right over track switch BTS. For West-bound traffic to the left, signals 5A and 5B are provided for governing traffic over track switch BTS, and signals 3A and 3B are provided for governing traffic over track switch BTS.

The signals are of the color light type having a green indication for clear, a yellow indication for caution, and a red indication for danger or stop, each indication being provided by a separate color lamp unit. It is to be understood, however, that other types of signals such, for example, as search light signals and semaphore signals can as well be used.

; The track switches are positioned by power operated switch machines SM which can be of the type shown, for example, in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923. It is to be understood that track circuits are provided in the usual manner for the various track sections which are separated by insulated joints as illustrated, and that circuits for the switch repeater relays WP for repeating the normal and reverse locked position of the track switches are provided in the usual manner.

With reference to Fig. 1, a portion of the control machine provided for the track layout illustrated in Figs. 3A and 3B is shown in which a miniature track diagram on the control panel is representative of the track layout in the field for which that section of the machine is provided.

A switch control lever BSML, having a normal left-hand position and a reverse right-hand position, is provided on the panel of the control machine for governing the normal and reverse operations respectively of the track switch BTS; and lever 8SML, having a normal left-hand position and a reverse right-hand position is provided on the panel of the control machine for governing the normal and reverse operations respectively of the track switch 8TS.

A signal control lever 2-3SGL, having a normal center position corresponding to the danger indication of the associated signals, a lefthand position corresponding to a clear indication for either of signals 3A or 3B for westbound traffic, and a right-hand position for the clear indication for either of the signals 2A or 2B for east-bound traflic, is provided on the panel of the control machine for governing the signals associated with track switch GTS. A signal control lever 4--5SGL, having a normal center position corresponding to the danger indication of the associated signals, a left-hand position corresponding to a clear indication for either of signals 5A or 5B for west-bound traffic, and a right-hand position for the clear indication of either of signals 4A or 4B for eastbound traffic, is provided for governing the signals associated with track switch 8TS.

The slow acting relays lCl-I and 201-1 illustrated in Fig. 1 are associated with the starting of the communication system for the transmission of controls for the respective ends of the passing siding illustrated in Figs. 3A and 3B, and those relays also provide a means for storing starts designated by an operator when the communication system is not available for the immediate transmission of the particular controls designated. Suitable start push buttons I83 and ZSB are provided for the energization of the respective start relays CH, and a cancel button CNB is provided to allow an operator to cancel a start which has previously been designated but has not yet been transmitted.

The code determining relays ICD and 2CD are used in selecting the order in which stored starts are to become efiective.

The relays PC, NC, E, EP, F, FP, 2FP, SA, ZSA, C, FC, CDS, CHP, MF, MB, DV, VP, IV, 2V, 3V, 4V, 5V and LV are used in the communication system .for purposes set forth in detail in the above-mentioned Judge et al. Patent No. 2,082,544, in order to provide proper operation of the communication system, stepby-step, for the transmission of controls to the field stations, and for the reception of indications as to the position of the various devices at those field stations.

Field station receiving equipment is provided at each of the field stations, one field station for each end of the passing siding, in accordance with the system disclosed in the abovementioned Judge et a1. patent; and, in addition to the receiving apparatus at each of the field stations, suitable application relays are provided for governing the power operation of levers 2-3SGL and *4--5SGL are illustrated :as

the track switches and the indications of .the signals in accordance with the control codes received from the control oifice, and in accordance with the block signal control as provided in the field. Thus, the relays ZGZ, EAG and ZBG are provided for governingthe indication of the signals 2A and 2B, dependent upon the controls received from the control o-ifice, and relays 3GZ, SAG and 3BG are provided for governing the indication of the signals 3A and 3B in accordance with controls received from the control office. The relay 2-3B is provided in order that either of the signals for governing traffic over the track switch 6T8 may be restored to stop responsive to the transmission of a stop code for such signal from the control The normal and reverse switch control relays GWN and SWR are provided for causing the operation of the switch machine BSM to normal or reverse positions respectively in accordance with the control codes received from the control ofiice.

The correspondence relays fiNCR and GRCR are used in the selection of the particular signal to be cleared in accordance with the route established after the track switch BTS has completed its operation in accordance with controls received from the control ofiice.

In a similar manner corresponding relays for corresponding purposes are provided for the opposite end of the passing siding for governing the track switch 8T8, and the signals provided for governing traific thereover.

Suitable home relays H are provided for automatically governing the indication of the signals in accordance with the condition of occupancy of the track sections in advance of such signals, and for other purposes hereinafter set forth and for purposes well known to those familiar to the art.

Inasmuch as the present invention is more particularly related to a circuit interlock on the control levers in the control ofiice, certain details relative to the control of the application relays have not been shown, as a more detailed description of the control of such relays can be obtained by referring, for example, to the patent to T. J. Judge, Patent No. 2,045,951, dated June 30, 1936.

Having thus considered the apparatus employed in the system provided by the present invention, consideration will now be given to the general mode of operation of the entire system, and the novel features of the present invention will be more specifically pointed out.

When the communication system is inactive, that is, when there are no controls being transmitted, and there are no indications being received, it is said to be at rest. The conditions of the system illustrated in which the signals are all at stop, the track switches are normal, and the communication system is at rest, are, for the pur pose of description of the present invention, called the normal conditions of the system. Under such conditions the relays illustrated in Figs. 1 and 2 are dropped away as shown, and the application relays in the field are dropped away with the exception of the normal or reverse switch control relay energized in accordance with the position of the associated track switch. The switch control levers at the control oflice (see Fig. l) GSML and BSML are illustrated as being in their left-hand normal positions to correspond with the normal positions of the track switches BTS and 8T8, as the last position required for such track switches is assumed to have been for a through route on the main track. The signal control being in their center positions to correspond with thedangerindication assumed to be normally displayed by :their respective signals.

When an operator wishes to transmit controls to any one of the field stations, he first positions the switch and signal control levers for that field station in accordance with the controls he wishes to transmit. After having positioned the switch and signal control levers in accordance with controls to be transmitted, the operator actuates the start button SB associated with that field station, and, if the system is at rest, the controls are transmitted immediately. If the system is already in operation, the controls are transmitted as soon as the system is available for their transmission. More specifically, the actuation of a start buttonSB causes the picking up of .a change relay H for that particular field station, and

the picking up of that relay sets the system into operation for the transmission of controls at a time when the communication system is available for their transmission to the respective field station for which they are intended. Each change relay CH, when picked up in such a manner, remains picked up until the transmitter is set into operation for the transmission of the controls for that field station. Thus, a means is provided for storing a control office start of the system for the transmission of controls to a particular field station if such start cannot be effected immediately upon actuation of the start button.

The controls are transmitted by a series of 'im pulses of selected polarity through a control cycle of operation of the system. The impulses transmitted during the first part of a control cycle form a station code and select the particular field station to receive the controls, and the following series of impulses during a control cycle forms a control code for track switches and signals at the field station selected during the first part of that cycle.

The field station associated with track switch BTS is assumed to be responsive to a station code having the characters determined (see Fig. 1) by

jumpers

58, 55 and 40 at the control ofiice; and the field station associated with track switch BTS is assumed to be responsive to a station code having the characters determined by jumpers 380, 30| and 302.

If the first impulse of the control code is the track switch for the field station selected by the station code is caused to be operated to a normal position, and if the first impulse of the control code is the track switch at the field station selected by the station code is caused to be operated to a reverse position. The second and third impulses of the control code, taken together, provided control for the signals. That is, if the second control impulse is and the third control impulse is a signal is cleared for east-bound trafiic. However, if the second control impulse is and the third control impulse is a signal is cleared for west-bound traffic. If both second and third control impulses are a signal is restored to danger.

As a means for preventing the clearing contemporaneously of the opposing signals (see Figs. 3A and 313) 2A and A for the main track, an interlock is provided in the block signal control circuits in the field to allow the clearing of only one of such signals at one time. Such an interlock can be provided as shown, for example, in the control of the relays ZAH and EAH. Relay ZAH is normally energized by a circuit closed from (B)., through a circuit including back contact 303 of relay IAG, back contact 304 of relay SAG, front contact 305 of relay 8TB, front contact 306 of relay 'ITR, wire 301, front contact 308 of relay 6TB, and winding of relay 2AH, to (ON). Upon considering the above described circuit, it will be readily apparent, that, with signal control relay SAG picked up to clear signal 5A, back contact 304 in the circuit for relay ZAI-I is opened to cause that relay to be dropped away, and the dropping away of that relay prevents the energization of the signal control relay 2AG by opening an obvious circuit for that relay at front contact 309. In a similar manner an interlock is provided whereby signal 5A cannot be cleared at a time when the opposing signal 2A is cleared.

Thus, dependent upon block signal control, an interlock is provided in the field between the 0pposing signals for the main line of traffic, however, inasmuch as signals 2B and 5B are low speed signals, and there are no track circuits provided for the passing siding, there is no interlock provided in the field for those low speed signals As a means for preventing the clearing contemporaneously of signals 23 and 5B, it is provided in the control office that relay lCH (see Fig. 1) is responsive to the actuation of the start button ISB at all times except when lever BSML is in a righthand position, lever 8SML is in a right-hand position, lever 2--3SGL is in a right-hand position, and lever 4-5SGL is in a left-hand position. 'And similarly, as a means for preventing the clearing contemporaneously of signals 2B and 53, it is provided for the field station at the opposite end of the passing siding that relay 20H is responsive to the actuation of the start button 283 at all times except when lever GSML is in a right-hand position, lever BSML is in a right-hand position, lever 2-3SGL is in a right-hand position, and lever l-ESGL is in a left-hand position.

To consider more specifically how the circuits are provided to satisfythe above conditions, assume an operator to depress the start button ISB at a time when the normal conditions of the system exist as they have been described. Upon depression of that button, relay ICH is picked up by the energization of a circuit closed from through a circuit including contact 3| 0 of button ISB closed in a depressed position, winding of relay ICH, contact 3 of lever BSML in a lefthand position, and contact 3I2 of cancel button CNB closed in a normal position, to Upon the picking up of relay ICH a stick circuit is closed for that relay from through a circuit including back contact 3I'I of relay ICD, front contact 3l8 of relay ICH, winding of relay ICH, contact 3 of lever GSML closed in a lefthand position, and contact 3l2 of cancel button CNB closed in a normal position, to- Such stick circuit together with the slow action in relay ICH, provides that relay ICH is maintained picked up until relay ICD is picked up and has its stick circuit closed at the beginning of a control cycle for the transmission of the controls selected for that particular field station. The picking up of relay ICD causes the restoration of relay ICH to its normal deenergized position by opening its stick circuit at back contact 3H.

Connected in multiple with contact 3 closed in a left-hand position of lever GSML in the pickup circuit for relay ICH is contact 3M of lever 23SGL which can be closed with that lever in either a center or left-hand position, contact 3|5 of lever 8SML which can be closed when lever 8 SML is in a left-hand position, and contact 3|6 of lever 45SGL which can be closed when lever 4-5SGL is in either a normal or a righthand position. Thus, it is provided that relay ICH can be energized when button ISB is depressed whenever the levers BSML, 2-3SGL, 8SML, and 4-5SGL are in any positions other than the combination of positions required for clearing opposing signals for train movements into the siding. That is, relay ICH can be picked up when button ISB is depressed at any time except when lever GSML is in a right-hand position, lever 2-3SGL, is in a right-hand position, lever BSML is in a right-hand position, and lever 45SGL is in a left-hand position. Under such conditions the circuit for relay ICD is held open at contacts 3| I, 3l4, 3l5 and 316 respectively to prevent the picking up of that relay.

Inasmuch as the relays ICH and 2CH are controlled by similar circuits, it is obvious that relay ZCH is subject to the same circuit conditions as relay ICH.

The picking up of a CH relay, such as relay I OH, sets the system into operation for the transmission of controls by causing the picking up of relays CHP, C and ICD respectively, in a manner the same as that described in the above mentioned Judge et a1. Patent No. 2,082,544. In view of the fact that the picking up of relay ICH is required before controls can be transmitted for the clearing of a signal; such as signal 2B, it is believed that it is readily apparent that the prevention of the picking up of relay ICH at the control oiiice at a time when the levers are positioned for clearing opposing signals 2B and 5B prevents the clearing of signal 23 and thus prevents two approaching trains from proceeding into the siding from opposite directions.

Having described the present invention as applied to a particular communication system of the coded type as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the forms that the invention may assume, and, it is to be further understood that various alterations, adaptations and modifications may be made, in accordance with the requirements of practice, without in any way departing from the spirit or scope of the present invention except as limited by the appending claims.

What we claim is:

1. In a coded centralized trafiic controlling system of the character described for governing the power operation of track switches and the clearing of signals remotely located from a control office, a track layout having a main stretch of track and a passing siding connected thereto at opposite ends by power operated track switches, signals for governing traffic over each of the track switches in both directions, a freely movable switch control lever at the control oflice for each of the track switches, a freely movable signal control lever at the control ofiice for the signals, respectively, at each end of the siding, a transmitter at the control oifice operable, when rendered effective, to transmit controls from the control ofiice to said track switches and signals, and circuit means, including contacts controlled by said control levers, for rendering said transmitter effective for the transmission of controls each time such controls are designated for transmission at the control office except when said switch and signal control levers for each end of the siding are contemporaneously positioned for governing trafiic into that siding from opposite directions.

2. In a switch and signal control system of the character described, a stretch of main track having an associated passing siding, power-operated track switches at the opposite ends of the passing siding, signals at each end of the passing siding for governing trafiic over the stretch of main track and onto the passing siding, said main track signals giving high speed indications and interlocked with wayside circuits to allow only one of such signals to be cleared at the same time, and said signals governing traffic onto the passing siding giving low speed call-on signal indications, code receiving apparatus located along the trackway and responsive to the reception of control codes for governing said poweroperated track switches and signals, a normallyat-rest code type communication system connecting a control office with said code receiving apparatus, a switch control lever at the control office for the track switch at each end of the siding, said switch control lever being operable to normal and reverse control positions, a signal control lever associated with the signals at each end of the passing siding and having clear and stop positions for governing said signals, a manually operable start button for each end of the passing siding, a start relay at the control ofiice for initiating said communication system into operation when such relay is operated, and circuit means, including a contact, respectively, controlled each by one of said control levers, for operating said start relay when a start button is actuated only if said switch and signal control levers for the opposite ends of the passing siding are not in positions to clear both of said low speed signals at the same time, whereby the sig nals governing trafiic in opposite directions over the main track are prevented from being cleared by wayside signalling circuits while the low speed signals governing traific over the passing siding are prevented from being cleared by reason of the start circuit means for the code type communication system in the control office.

3. In a centralized trafiic controlling system in which track switches and signals remotely located from a control office are controlled in accordance with codes transmitted during the various operating cycles of a normally-at-rest code type communication system, a track layout having a main stretch of track and a passing siding connected thereto by a power operated track switch at each end of the siding, signals for governing trafiic in both directions over said main stretch of track and over said siding, freely movable manually operable switch control devices at the control ofice having distinctive operated positions for governing said track switches, manually operable signal control devices at the control office having distinctive positions for governing the clear and stop indications of said signals, a normally-at-rest code type communication system connecting the control oifice with the remote track layout and effective when set into operation to transmit control codes from the control ofiice and to receive such control codes at the track layout for governing the operation of said track switches and signals, said control codes being selected in accordance with the distinctive positions of said manually operable switch and. signal control devices, electro-responsive means effective when energized to set said communication system into a cycle of operation for the transmission of control codes, and circuit means for controlling the energization of said electroresponsive means, said circuit means including contacts of said switch and signal control devices which contacts are opened whenever said devices are positioned 'to control said track switches to positions for train movement onto saidsiding and to positions for clearing opposing signals governing trafiic onto said siding.

4. In a centralized trafiic controlling system in which track switches and signals remotely located from a control office are controlled in accordance with codes transmitted during the various operating cycles of a normally-at-rest code type communication system, .a track layout having a main stretch of track and a passing siding connected thereto by a power operated track switch at each end of the siding, signals for governing traffic in both directions over said main stretch of track and over said siding, freely movable manually operable switch control devices at the control oil-ice having distinctive operated positions for governing said track switches, manually operable signal control devices at the control ofiice having distinctive positions for governing the clear and stop indications of said signals, a normally-at-rest code type communication system connecting the control oflice with the,

remote track layout and effective when set into operation to transmit control codes from the control oifice and to receive such control codes at the track layout for governing the operation of said track switches and signals, said control codes being selected in accordance with the distinctive positions of said manually operable switch and signal control devices, electro-responsive means effective when energized to set said communication system into a cycle of operation for the transmission of control codes, and circuit means for controlling the energization of said electroresponsive means, said circuit means including in multiple, a contact controlled, respectively, by each of said control devices, the contact of each of the switch control devices being open when its device is positioned for movement onto the siding, the contact of each of the signal control devices being closed when its device is positioned to put the signals to stop.

5. In a centralized traffic controlling system in which track switches and signals remotely located from a control ofiice are controlled in accordance with codes transmitted during the various operating cycles of a normally-at-rest code type communication system, a track layout having a main stretch of track and a passing siding connected thereto by a power operated track switch at each end of the siding, signals for governing traific in both directions over said main stretch of track and over said siding, freely movable manually operable switch control devices at the control ofi'ice having distinctive operated positions for governing said track switches, manually operable signal control devices at the control oflice having distinctive positions for governing the clear and stop indications of said signals, a normally-at-rest code type communication system connecting the control office with the remote track layout and effective when set into operation to transmit control codes from the control oiiice and to receive such control codes at the track layout for governing the operation of said track switches and signals, said control codes being selected in accordance with the distinctive positions of said manually operable switch and signal control devices, electro-responsive means effective when energized to set said communication system into a cycle of operation for the transmission of control codes, and circuit means for controlling the energization of said electro-responsive means, said circuit means including in multiple, a contact controlled, respectively, by each of said control devices, the contact of each of the switch control devices being open when its device is positioned for movement into the siding, the contact of each of the signal control devices being closed when its device is positioned to put the signals to stop, and open when positioned to clear opposing signals governing movement onto the siding.

6. In a centralized trafiic controlling system in which track switches and signals remotely located from a control ofiice are controlled in accordance with codes transmitted during the various operating cycles of a normally-at-rest code type communication system, a track layout having a main stretch of track and a passing siding connected thereto by a power operated track switch at each end of the siding, signals for governing trafiic in both directions over said main stretch of track and over said siding, freely movable manually operable switch control devices at the control oflice having distinctive operated positions for governing said track switches, manually operable signal control devices at the control ofiice having distinctive poistions for governing the clear and stop indications of said signals, a normally-at-rest code type communication system connecting the control oflice with the remote track layout and effective when set into operation to transmit control codes from the control office and to receive such control codes at the track layout for governing the operation of said track switches and signals, said control codes being selected in accordance with the distinctive positions of said manually operable switch and signal control devices, electro-responsive means effective when energized to set said communication system into a cycle of operation for the transmission of control codes, andcircuit means for controlling the energization of said electro-responsive means, said circuit means including in multiple, a contact controlled, respectively, by each of said control devices, the contact of each of the switch control devices being open when its device is positioned for movement onto the siding, the contact of each of the signal control devices being closed when its device is positioned to put the signals to stop, the contact of one of said signal control devices being open when its device is positioned to put its signal governing movement onto the siding in one direction, to clear, and closed when positioned to put its signal governing movement off of the siding in the opposite direction, to clear, the contact of the other said signal control device being open when the control device is positioned to put its signal governing movement onto the siding in the opposite direction, to clear, and closed when its device is positioned to put its signal governing movement off of the siding in said one direction, to clear.

'7. In a centralized traffic controlling system in which track switches and signals remotely located from a control OfiiCB are controlled in accordance with codes transmitted during the various operating cycles of a normally-at-rest code type communication system, a track layout having a main stretch of track and a passing siding connected thereto by a power operated track switch at each end of the siding, signals for governing trafiic in both directions over said main stretch of track and over said siding, freely movable manually operable switch control devices at the control oflice having distinctive operated positions for governing said track switches, manually operable signal control devices at the control office having distinctive positions for governing the clear and stop indications of said signals, a normally-at-rest code type communication system connecting the control oflice with the remote track layout and effective when set into operation to transmit control codes from the control ofiice and to receive such control codes at the track layout for governing the operation of said track.

switches and signals, said control codes being selected in accordance with the distinctive positions of said manually operable switch and signal control devices, electro-responsive means effective when energized to set said communication system into a cycle of operation for the transmission of control codes, and circuit means for controlling the energization of said electro-responsive means, said circuit means including in multiple, a contact controlled, respectively, by each of said control devices, the contact of each of the switch control devices being open when its device is positioned for movement onto the siding,

the contact of one of said signal control devices being open when its device is positioned to put its signal governing movement onto the siding in one direction, to clear, and closed when positioned to put its signal governing movement off of the siding in the opposite direction, to clear, the contact of the other said signal control device being open when the control device is positioned to put its signal governing movement onto the siding in the opposite direction, to clear, and closed when its device is positioned to put its signal governing movement oil of the siding in said one direction, to clear.

8. In a centralized trafiic controlling system in which track switches and signals remotely located from a control ofiice are controlled in accordance with codes transmitted during the various operating cycles of a normally-at-rest code type communication system, a track layout having a main stretch of track and a passing siding connected thereto by a power operated track switch at each end of the siding, signals for governing traffic in both directions over said main stretch of track and over said siding, freely movable manually operable switch control devices at the control oflice having distinctive operated positions for governing said track switches, manually operable signal control devices at the control oflice having distinctive positions for governing the clear and stop indications of said signals, a normally-at-rest code type communication system connecting the control office with the remote track layout and efiective when set into operation to transmit control codes from the control ofiice and to receive such control codes at the track layout for governing the operation of said track switches and signals, said control codes being selected in accordance with the distinctive positions of said manually operable switch and signal control devices, electro-responsive means effective when energized to set said communication system into a cycle of operation for the transmission of control codes, and circuit means for controlling the energization of said electroresponsive means, said circuit means including in multiple, a contact controlled, respectively, by each of saidcontrol devices, the contact of each of the switch control devices being open when its device is positioned for movement onto the siding, thecontactof one of said signal control devices being open when its device is positioned to put its signal governing movement onto the siding in one direction, to clear, and closed when assuming any of its other positions, the contact of the other said signal control device being open when the control device is positioned to put its signal governing movement onto the siding in the opposite direction, to clear, and closed when assuming any of its other positions.

9. In a switch and signal control system in which controls are transmitted from a control oiiice to a plurality of field stations over a line circuit, a. track layout having two opposing signals for governing tramc into a particular stretch of track, freely movable manually operable control means at the control oflice having distinctive positions corresponding to clear and. stop indications of each of said signals, a normally-at-rest communication system efiective to transmit controls to the field stations for controlling said signals to clear or stop in accordance with the positions of said manually operable control means when said communication system is set into operation, and contacts associated with said control means effective to set said communication system into operation only if the position of said manual control means is other than that corresponding to the clearing of both opposing signals into the same stretch of track.

WILLIAM D. HAILES.

REGINALD F. ALBRIGHTON.