Patent GB-589750-A (GB)
Title: Improvements relating to remote control systems for railways and the like
IPC: B61L7/08
Filed: 1944-07-28
Abstract: 589,750. Electric selective signalling systems. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. July 28, 1944, No. 14449. Convention date, July 31, 1943. [Class 40 (i)] In a remote control system using a signalling code comprising two groups of long and short elements, the first group forming a station code call and the second identifying the controlled devices and their conditions, a normally energized starting relay is released when any of the devices is moved and so initiates transmission of an indication code ; it is re-energized over a temporary locking circuit at the end of the first group of elements, this circuit being opened if transmission is interrupted, and the energization is transferred to the normal locking circuit when the second group is transmitted. The code employed consists of sixteen pulses, alternate pulses being current and no-current on the line YZ, Fig. 1A. The first pulse is long for a control code, sent from the office, and short for an indication code, sent from a station to indicate the condition of the devices thereat. Impulses 2 to 8 incorporate three long pulses, to provide a station identifying signal in both control and indication codes. Impulses 9 to 15 perform the control or indication function, as appropriate, and the final impulse restores the equipment to normal. Control station, Figs. 1A, 1B, 1c. The operator presses the starting button STB, appropriate to the desired station, and so locks relay ST and operates, master relay OM. Contact OMd completes a pulsing circuit for transmitter relay OT, which picks up to begin the first step of the code. Its contacts b and d open the line to release all line relays at the various stations and contact c reverses receiving relay OR, which then operates timing relays OL1, OL2, OLP, OLB, relay OLBP, which is held to the end of the code and the first counting relay 01. During subsequent transmission. relay OR follows the operation of OT and in turn operates the counting relays 02 to O8 and 016 sequentially each time it records a transmitted pulse, the cycle 01 to 08 being repeated after the eighth step by chain repeat relay OCR. On the Àhort pulses, the transmitting relay OT is operated or released, for even or odd pulses respectively, each time a counting relay picks up, but for long pulses this action is delayed, by a parallel holding circuit or by a short-circuiting connection, over wires 61 or 62 and contacts of the counting relays in sequence, to individual wires 32 to 46 which are selectively connected to battery by contacts E, F', G for the station code and to control switches SW &c. for the control signal. In such cases the timing of each pulse is determoned by timing relays OL1 or OL2 and OLP, which terminate the pulses when they release. When indication codes are received at the control station, the signals are passed through transformer RT to receiving relay OR and this controls the timing relays as above. The counting relays operate in the same manner as during transmission and if the timing relays have time to release before the end of any given pulse, i.e. if the pulse is long, they complete circuits over wires 63, 64 and contacts of the counting relays to wires 21 to 30 for identifying the station and through relays 9 to 15 and wires 49 to 56 for operating the control relays NWK &c. Station equipment incoming signal, Figs. 2A, 2n, 2c. At all stations the line relay R and timing relays L1, L2, LP, LB and LBP operate in unison with the corresponding office relays, and the counting relays 1 to 8 operate through the first eight steps. However, only one station. is selected and this conditions its equipment to respond to the second cycle. Owing to the long character of the first step, relay L releases white counting relay 1 is still held and so completes a circuit for relay CD, over Lld and 1c, and CD thereupon locks over its lower winding. Short impulses, of the subsequent code, only advance the counting cycle, but on long pulses the release of L1 or L2 operates selector relays FA, GA, S, which are connected to wires 122 to 128 in a combination characteristic of their particular station, the circuit including the d contacts of the counting relays. Owing to the interconnection of the selector relays the S relay at one station only is selected for any given code. This prepares a circuit for chain repeat relay CR at Sd which is completed on the eighth step by 8f. D is now energized over CRc, CDc and wire 115 and locks until the end of the code. When any subsequent control step is long, L1 or L2 releases, on. odd or even-numbered steps respectively, and over its d contact operates P1 or P2 which remains held over Ra during the following pulse while contact P1b or P2b completes a circuit over wire 111 or 112 and counting relay contact e to the winding of the control relay FS &c. These control relays may either be operated by current through the appropriate winding, as WS, or by reversal of the current by change-over contacts b, c of the pilot relays P1, P2 as with FS, MCS, COS. Transmission of indication code. Indication codes are similar to control codes, but commence with a short first pulse so as to select the office, and are initiated automatically in response to a change in condition of any of the indicating relays RHR &c. by releasing ST, which is normally energized over STa and c contacts of the indicating relays. If the line circuit is available, the starting circuit to relay M is closed over wire 147. Contacts Mb and Md reverse the connections of receiving relay R to the line wire and provide a low impedance shunt across the line wires through CDf and LBPf. Owing to this shunt, relay R releases and, at the office, the increase in line current from battery causes transformer RT to reverse relay OR in unison with R at the station. The timing relays and first counting relay at the station and office are operated, but in the latter case relay PC, Fig. 1A, is operated over wire 17 and ORa and reverses the direction of the line current. This reversal indicates to the station that the office is ready to receive, by allowing its relay R to move over for its second step. The pulsing circuit of relay T at the station is now complete and T transmits by means of its contact b, which provides a low resistance shunt across the line each time it is operated. The determination of long or short elements for the station code is provided by circuits set up over counting contacts c and coded contacts of relays FA, GA, S, these providing short-circuit or continued operation of T as necessary. On the eighth step relay CR picks up over 8f to repeat the counting cycle while at CRa it locks to wire 160 and completes a circuit for starting relay ST over contacts c of the indication relays RHR &c.. If transmission is interrupted for any reason during the second half of the cycle, LBP releases and breaks this circuit at contact a, so conditioning the apparatus to retransmit the indication when the line becomes available. At its contacts e, f, CR prepares circuits over counting relay contacts f and wires 139 to 146 to the indication relay contacts b so that battery may be applied as necessary to wires 161, 162 to produce long or short steps. On the sixteenth step, relay 16 releases master relay M at 16e and this restores the original line connections to relay R to make it responsive only to line current of normal polarity. The timing relays release and S is released by LBPa, thereby restoring ST to its normal holding circuit. The receipt of an. indication. code at the office is performed similarly to the receipt of a control code at the station and at the end of the signal all relays release except the indication relays NWP &c. which remain held over their a contacts until a new indication is received. In order to ensure that the passage of a train through a controlled section is indicated even if the train has left the section before the line wire becomes free for the transmission, a normally operated storage relay TKS is released when a train enters the section, so releasing ST which, at contact STd holds TKS released until the indication has been sent. If two stations initiate indication codes at the same time, the order of precedence is determined by their codes since a station applying a shunt to the line on any given pulse automatically over-rules any station tending to hold it normal at the same instant. At the inferior station this causes release of its timing relays and storage of its indication until the line becomes free. If, however, it is desired to have a station of high priority at a remote point, such that shunting of the line would not be effective, a modification described with reference to Fig. 3 (not shown) and incorporating a secondary transmitter relay TS at the control office is employed. Provision is, however, made, by relay SS at each station, to prevent stations having superior code calls from monopolizing the line wire, whereby any station which has transmitted a code cannot again transmit as long as any other station has a code stored for transmission. This feature; together with a thermal relay COR, prevents the repeated transmission of incomplete codes due to a fault. A modification by means of which the line wires may be used jointly by the signals as described and by a telephone system between stations is described with reference to Fig. 4 (not shown). In this modification, stations are selected for telephone communication by means of a selector code over relays having contacts connected in the normal transmitting and receiving circuits. Specifications 415,787, 528,745 and 528,747 are referred to. The Specification as open to inspection under Sect. 91 contains also the subject-matter of Specification 589,798. This subject-matter does not appear in the Specification as accepted.