Patent GB-938502-A (GB)
Title: Remote control and indication system
IPC: B61L7/08
Filed: 1960-02-04
Abstract: 938,502. Central traffic control systems. WESTINGHOUSE AIR BRAKE CO. Feb. 4, 1960 [Feb. 4, 1959], No. 3963/60. Class 105. In a railway C.T.C. system in which track switches and signals at a number of field stations, e.g. stations 235 and 236, Fig. 1A, are controlled from a central office by coded commands transmitted over a single line circuit connecting the office and the stations and in which the same line circuit is used to transmit to the office coded signals indicating the position assumed by the track switches and signals at the field stations, the office indicating apparatus associated with a field station is used to store commands for that field station until the commands have been transmitted to the station and carried out, after which the apparatus is reverted to its indicating function by the indicating signals received from the station. The central office equipment includes a control panel with means for selecting any field station in the area controlled, switches for controlling the signals and track switches at the selected station and means for initiating a code start for transmission of the control commands to the selected station, a miniature track diagram with lamps, e.g. 35-1WRKE and 35-2RAKE for indicating the condition of the track switches and signals at each field station, indicating relay means for each field station for controlling the lamps and storing command signals and means for storing a code start for the selected station until the code communication system, which is of the type which transmits only one group of coded signals at a time to or from the central office, is available. The office indicating relay means associated with each field station comprises track switch indicating means including normal and reverse indicating relays both of which are energized to store a " switch to reverse " command and released to store a " switch, to normal " command and signal indicating means comprising left and right indicating relays and an auxiliary relay which when released indicates all signals at stop, when either left or right relays are energized store a command to clear the signal controlling traffic to right or left respectively and when either right or left relays are energized in conjunction with the auxiliary relay indicate that right or left signals respectively have been cleared for traffic. Assuming the track switch 35-1W at field station 235 (location 35 has to be changed from its normal to reverse position, location 35 is first selected on the office control panel whereby a location relay 35LC is energized and locked, next a reverse switch control pushbutton IRPB, Fig. 3A, is depressed whereby relay IRP is energized over (front contact) f.c.c. relay 35LC and (back contact) b.c.b. of relay 35-IRWK and finally a code start pushbutton is depressed which stores a code start for transmission of the control command to the selected field station. When relays 35LC and IRP are energized normal switch indication relay 35-INWK, Fig. 5, remains energized over b.c.d. relay INP, f.c.L relay 35LC, its own f.c.a. and b.c.a. relay 235D and reverse switch indication relay 35.IRWK energizes over f.c.e. relay IRP and f.c.K relay 35LC. If another location is now selected from the control panel, relays 35LC and IRP release but the indication relays stick over b.c .h. of relay 35LC. The energized condition of both relays stores a " switch to reverse " command and this condition is indicated on the track diagram by the flashing of lamp 35-1WRKE which is supplied with coded battery CB over a front contact of each relay. When the communication system is available a relay 235S energizes whereby the control command is passed via .c.d. relay 235S, Fig. 4a, f.c.c. relay 35-1RWK, f.c.b. relay 35-1NWK. and the communication system to switch the track switch control relay 35-1NRWSR to its reverse position. Whilst the track switch is changing over both correspondence relays 35-1NWCR and 35-1RWCR, Fig. 5, are released and terminals 1 and 3 are energized over contact a of relay 35-1NRWSR in reverse position. This condition is transmitted to the central office energizing terminals 9A and 11A and as delivery relay 235D is picked up by the code signal relays 35-INWK and 35-1RWR are maintained energized over f.c.a. and b relay 235D, respectively. As relay 235D releases the indicating relays are held over their stick circuits. When the track switch reaches its reverse position, correspondence relay 35-1RWCR energizes, de.energizing terminal 1 at its contact a and energizing terminal 3 over its f.c.b. This condition is transmitted to the central office and when relay 235D picks up, relay 35-1NWK releases and relay 35.1RWK remains energized and is maintained energized over its stick circuit when relay 235D releases. Relay 35-1RWK is now performing its indicating function and steady battery is applied over one of its contacts and over a back contact of relay 35-1NWK to the lamp 35-1WRKE.