Patent GB-754181-A (GB)
Title: Improvements relating to remote control systems
IPC: B61L7/08
Filed: 1954-09-01
Abstract: 754,181. Selective signalling and controlling. WESTINGHOUSE AIR BRAKE CO. Sept. 1, 1954, [Sept. 29. 1953], No. 25389/54. Class 40(1) In a system involving a control office and a number of controlled stations on a party line and making use of a code of which the first part designates a station and the second part a control or indication of the condition of apparatus and in which the number of steps necessary in the second part varies from station to station means are provided to ensure the simultaneous termination of the code at the office and the station as soon as the number of steps necessary for the office concerned have been made. The invention is described with reference to a system resembling that described in Specification 589,750 modified differently from the system described in Specification 753,806 [Group XXXVH] to provide supplementary arrangements for extending the number of control and indicating steps at such stations as may require it. General operation. The code consists of a train of impulses of current and absence of current alternately, the impulses of either kind being long or short in accordance with the control or information to be conveyed. These impulses are generated at the control office by the interaction of a pair of relays O1T, O2T and counted by a local chain O1 ... 08. The impulses are also repeated to a timing set O1L, O2L, OLP, OLB, OLBP the arrangement being such that in positions in which a long impulse is to be sent, one of the relays O1T, O2T finds a holding circuit via a contact of one of the counting relays, such circuit being broken in due course on the relapse of one or other of the timing relays O1L, O2L and relay OLP. The first eight steps are devoted to the station selecting code after which a relay OCR is operated to enable the chain O1...O8 to build up again for the control part of the code. The above arrangements apart from the provision ot completion of the control operation. Since the first step of a control signal is always long O1T remains locked after the operation of the first counting relay and is not released until the sluggish relapse of O1L OLP. Battery is now connected to line again to start the next step, OR changes over and the even transmitting relay O2T takes over. This energizes the next counting relay and timing relay O1L. If the next step is to be a long one, a circuit will exist for holding O2T over wire 71, the top a pair of interacting transmitting relays are almost the same as those described in Specification 589,750, but one or more additional counting chains such as 17/21 ... 18/22 are provided for giving additional control steps for such stations as need it To avoid waste of line time, it is provided, according to the present invention, that a relay OCS is operated to stop the control transmission when the last significant step for the station concerned has been transmitted. Transmission of control signal. On the operation of a starting button such as 234 STB, the corresponding start relay 234ST pulls up, locks and energizes OM which disables the receiving arrangements and energizes odd transmitting relay O1 to produce the first step of the code. O1T disconnects battery from the line to release the distant line relays R and bridges it at R4 to dissipate any charge. It also changes over the local line relay OR and energizes O2T. OR energizes the first counting relay O and the first timing relay O2L which is followed by O2L. OLP, OLB, OLBP which holds until the contact of relay E (energized by the first counting relay) and contacts of the relay such as 234ST, individual to the station being called, until the relapse of the timing relays O2L, OLP energizes the selector relay (e.g. 2F) appropriate to the call being made. O2T is then unlocked and the next step is initiated. If this also is long. O1T finds a holding circuit over wire 70 via contacts of the energized F relay and is unlocked by the energization of a G relay such as 23G by the relapse of O1L, OLP. The G relay also unlocks the F relay and the holding circuit on wires 70 71 is thus made to depend on the energization of a particular relay individual to the station to be called. The arrangement is thus such that several calls may be set up simultaneously, priority being given to calls with long impulses in the early steps. For the stens in which the impulses are short, O1T, O2T find no holding circuit and whichever operates is at once released by the operation of the other and the relapse of the timing relays OIL or O2L and OLP is prevented. The last long impulse of the code is terminated by the energization of the S relay (e.g. 234S) individual to. the wanted station and the consequent energization of relay SP and relapse of relay G. At the eighth step OCR pulls up and locks and the individual start relay such as 234ST is released. For subsequent steps, the transmitting relays O1T O2T are controlled to produce long impulses via wires 39 to 45 and 102 to 108 and push buttons operated in accordance with the control to be effected. After the operation of OCR, the chain O1 ... 08 builds up as before, but on this second operation 16 operates instead of O8 to provide for the operation of the additional counting chain 17/21 to 19/23 concerned with the supple- and S respond if the station-selecting part of the received code is that of the station shown, each one locking up and releasing the previous one. Relay S arranges for the eighth counting relay to energize relay CR to enable the chain to be re-operated during the controlling part of the signal and to provide for the subsequent operation of the supplementary chain if necessary. It also removes a resistor from the locking circuit of relay 8. This resistor is provided to ensure quick release of 8 at those stations that are not being called. To provide for additional code steps, a supplementary chain 1A...4A responds to the sixteenth and mentary control functions provided by the invention. On the twentieth step, OCRA pulls up to allow the supplementary chain to build up agian for further control. It is arranged, however, that the chain is not built up unnecessarily after the last step at which a control is possible at the station at which control is being exercised. To this end, OCS is energized in parallel with the next even counting relay following the counting relay' corresponding to the last control position for the station concerned. Since the number of control positions, for a given station is not necessarily the same as the number of indication positions, OCS is controlled by OMP which operates for control codes only. The step at which OCS operates can readily be changed at a connecting block. OCS on operating releases OM and the remaining relays fall back. Reception of control signal. Line relay R at each station responds to the control impulses and repeats them to the counting chain 1...8 and timing group 1L, 2L, &c. Since the first impulse is a long one, relay 1L is released and a circuit is made over both windings of SR. Relays F1R, G2R subsequent impulses, 4A operating CRA to enable 1A...3A to respond a second time. Any number of supplementary chains can be provided. Owing to the operation of CR, F1R now operates on long odd impulses and G2R on long even impulses and these relays via cross-connecting frames and contacts of the counting chains control the direction of operation of the selected control relays. At the termination of the control signal all the timing relays fall back to restore the station to normal. Transmission of indication code. The change-over of any piece of apparatus at a station, e.g. track storage relay 3TKSR releases ST which disconnects MSTP. When the line is available, relay M pulls up, reverses the connections of the line relay R, connects a low impedance impulsing shunt across the line and energizes transmitting relay 1T. At the same time relay R falls back and OR at the main office changes over and these relays operate the counting and timing relays as previously described. In addition, since OM is back, a relay PC operates at the main office locks up, reveres the line current and energizes PCP. No effect is produced on OR. When LB pulls up 1T and 2T interact in the same way as O1T O2T, at the main office. After the operation of LBP, the low resistance shunt is dependent on the position of 1T. This relay also controls the relay R which pulls up to make the second step provided that the main office readiness has been indicated by the current reversal produced by the operation of PC referred to above. The station identifies itself by the position of the three long impulses in the first eight steps of the code. These are controlled by the relays F1R, G2R, S which provide the holding ground for the transmitting relay IT or 2T until they are energized by the appropriate counting relays. After the operation of S the remaining impulses of the identification part of the code are all short. Relay CR is operated by the eighth step, M locks, re-energizes ST, and completes the circuits from the indicating relays of the apparatus at the station whereby relays 1T, 2T are held temporarily to prolong the appropriate code impulses. When the last significant code step is reached, relay CS operates in parallel with the counting relay concerned. Connections for this are effected at a connecting frame to enable the remaining circuits to be standard at all the stations. CS releases M which re-operates MSTP and reverses the line connections and OR responds at the control office to energize OCS which releases PC to restore the normal direction of the battery connections to the line. Reception of indication code. PC, PCP, E are energized on the first response of relay OR to line impulses and subsequent impulses operate the station-identification relays such as 2F, 23G, 234S. SP also is operated by the last step characterizing the station and KSP by the next. OCR pul