Patent GB-528745-A (GB)
Title: Improvements relating to electric remote control systems
IPC: B61L7/08
Filed: 1939-04-20
Abstract: 528,745. Electric control and signalling systems. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. April 20, 1939, No. 11923. Convention date, Aug. 5, 1938. [Class 40 (i)] Relates to a centralized control and supervision system for apparatus located at a plurality of remote points and particularly for railway signals and points at different stations along a track. Control and supervision are effected over a single line circuit-by timecoded impulses generated by relays. Means are provided for storing codes for subsequent transmission as long as the line is in use and for maintaining an established direction of transmission as long as there are codes stored for transmission in that direction, the stored codes being transmitted in a group, and a given order of code superiority. Transmission of any code which becomes stored after the transmission of a group of codes has been initiated is prevented until all codes of the group have been delivered. Figs. 1A and 1B show the control station equipment and Figs. 2A, 2B the equipment at an outlying station for controlling the signal and track apparatus shown in Fig. 3. Normally the line wire 5 which is common to all stations is energized by positive currents which operate line relays L1. Each control code consists of a series of twelve impulses and each indication code transmitted back from an outlying station has fourteen impulses, the impulses in each case being of negative polarity and of long or short duration according to the particular control or indication to be effected, the code being terminated by a short positive impulse. The first impulse of a code initiated when the line is free is employed to select the direction of transmission and thus prevent interference between codes initiated simultaneously at the control and outlying stations. The five impulses immediately following the "direction" impulse of a code are used to effect station selection on a station indicator panel and the remaining impulses control the position of the selected station equipment or the operation of the panel indicator depending upon the duration of transmission. Detailed description. A control code is initiated by the release of any one starting relay in the group S1, S2 in response to the operation of some of the control levers SW, LG, RG, CO. When a relay, say, S1, releases, corresponding code sending relay SP1 pulls up and operates the impulsing relay OT. Line wire 5 is thus opened and line relays L1 at all stations are released. The polarity changing relay PC at the control office is operated to reverse battery connections to the line and thereby ensure transmission of code impulses of a polarity opposite to that of the normal line current. Release of relays L1 releases YO which pull up the first relays P1 in the chains P1-P13 at all stations. P1 opens OT and line relays L2 are operated and cause re-operation of relays OT which release relays L2 and effect operation of the next chain relays P2. Relays P2 release OT and pull up relays L2 and this cycle of operations is repeated to step the chain relays at all stations in synchronism. The chain relays P2- P6 are connected pyramid fashion, e.g., relay P2 controls two P3 relays each of which controls two P4 relays and so on. Each P6 relay controls a set of relays P7-P13 individual to the different station panels. The time period of each step in the cycle of operations is controlled by the timed relays in the groups A2- D2, A3-D3. These groups are operated to effect a long or short pulse depending upon the marking of one or other of the leads 26, 27, 37, 38 in accordance with the position of the control levers SW, LG, RG, CO. During the transmission of the station code, relays Z at all stations other than the station to be selected are pulled up at various points in the cycle, the relays Z preventing further operation of the equipment at those stations. Station selection at the wanted station is effected when chain relays RY are operated and further operation of the station equipment effects operation of the relays NS, LHS, RHS, CHS in a manner which is characteristic of the time periods of the remaining impulses. These relays operate the switch points and signals of the railway track shown in Fig. 3. When the relays Pll at the control office and selected station are operated, the relay PC at the control office is released so that the last impulse is positive, and at the next step relays L1 are pulled up and the equipment is restored to normal. The operation of the system when an indicating code is initiated in a substation is similar to that previously described. Upon change of condition of apparatus at the sub-station a relay, e.g., KR, Fig. 3, is operated and a start relay S initiates the code transmission. Station relay ST picks up and energizes relay T which opens the line circuit and thereby starts the stepping cycle. The time period of the steps are determined by markings on the leads 126, 127, 137, 138 which are characteristic of the sending station, and the positions of the apparatus thereat. Relays Z at non-signalling stations are operative to lock-out those stations. An "indication" code may be initiated from the control station without causing control operations by a key RC, Fig. 1B, which causes an additional step in the control code to operate code sending relay SP, Fig. 2B. After a code has been initiated by any transmitter it cannot be interfered with by another and moreover if two or more codes are initiated simultaneously no interference can occur but the codes are transmitted one at a time in a predetermined order of code superiority. Specification 528,747 is referred to.