Patent GB-326790-A (GB)
Title: Improvements in or relating to electric signalling systems
IPC: B61L25/04
Filed: 1928-11-13
Abstract: 326,790. Siemens & General Electric Railway Signal Co., Ltd., Boot, J., and Challis, W. Nov. 13, 1928. Selective signalling - apparatus. - Relates to electric signalling systems for use in connection with railways and more particularly for giving information of approaching or departing trains to persons on a railway station. Information regarding successive train arrivals is displayed on a plurality of lamps which are selectively operated by stepping switches or relay chains responsive to characteristic impulse codes. Successive impulse codes relating to successive trains are recorded and stored by successive switches or relay chains and information relating to several trains may be displayed simultaneously. Subsequent signals beyond the capacity of the indicator also may be stored. The indications are cancelled in the order in which they are received and the arrangement is such that upon cancellation of a " first " indication, the " second " indication is transferred to the lamps corresponding to the " first " indication and so on, a stored indication being displayed on the freed bank of lamps. Transmitting, storing and indicator apparatus, Fig. 1. In the apparatus shown three indications of successive train departures may be displayed on the banks of lamps S, T, U and six successive indications may be stored in the registers 60 - -110 which in turn are brought under the control of a line relay 38 by the stepping switch 46. Indications are transmitted over the line wires W1, W2 under the control of a plurality of keys P1 - - P24 associated with a stepping switch 12, a characteristic number of impulses being sent according to the key operated. Each contact in the bank of contacts A of the switch 12 is normally marked by the corresponding key P. Upon depression of a key, battery is removed from the corresponding contact and a circuit is closed over the key contacts and contacts of preceding keys, wire 13, wiper 12A25, relay 23 and interrupter contacts 19. Relay 23 operates stepping magnet 16 which opens contacts 19 to release relay 23 and magnet 16 to step forward the switch 12. Stepping is continued over circuits including the bank contacts A and the contacts 19 until the appropriate bank contact is reached. Meanwhile impulses, the number of which is characteristic of the operated key, are transmitted over the line W1 by the relay 23. Upon cessation of impulsing a lamp in the bank L1 - - L25 corresponding to the operated key is illuminated over wiper 12B25 and contacts of slow-release relay 34. After transmission of a signal a " normal " key is operated to open the line circuit and restore the depressed signalling key to again mark the associated contact in one bank A and thereby complete the stepping circuit of the switch 12. In this manner the stepping switch is restored to normal and a lamp L25 intimating that cancellation is effected is operated. The keys PI - - P25 are arranged in such a manner that depression of a key mechanically releases a previously depressed key. The transmitted impulses operate, at the receiver, a line relay 38 and a slow release relay 37 which holds during impulsing. Line relay 38 impulses the stepping magnet 61 of the register 60 over the wiper 41A of switch 46 so as to set the register in a position corresponding to the transmitted signal and thereby select a lamp in the first bank. Upon cessation of impulsing the circuit of stepping magnet 39 of switch 46 is opened at the contacts of relay 37 and the switch 46 is stepped forward to bring the second register 70 under control of the line relay 38 in preparation for the reception of a. subsequent signal. De-energization of relay 37 also closes contacts 37/2, 37/3, 37/4 and a. circuit is closed over lead 152, wiper 126A of switch 125, and wiper 62A for the selected lamp in the bank. A relay 145 is operated in this circuit to maintain the lamp operated independently of contact 37/2. Transmission of a " second " signal operates register 70 in a similar manner and upon cessation of impulsing the appropriate lamp in the bank T is operated over wipers 126B, 72B. Switch 46 also is operated to switch in register 80 ready for a " third signal which operates a lamp in the bank U. Further signals may be registered on switches 90, 100, 110 but remain undisplayed so long as the indications on the banks S, T, U of lamps remain. Cancellation of the indication displayed on the banks is effected by a switch 137 which may be operated manually or by a train as it. leaves the platform. Depression of switch 137 closes a circuit over wiper 126H. wiper 62H, (off-normal) interrupter contacts 66 and stepping magnet 61, and the register 60 is driven to normal and the selected indication is cancelled. A slow-release relay 134 is energized in series to maintain the " homing " circuit independently of switch 137 and to energize stepping magnet 127 of switch 126. When the register arrives at normal, relay 134 is de-energized to operate switch 126 one step. Circuits are now closed over wipers 126A, 126B and wipers 72A, 82B of registers 70, 80 respectively for lamps in the banks S, T, so that the original " second " and " third " indications appear as " first " and " second " indications, the indication in the bank U being cancelled due to the movement of wiper 126C. A new indication is, however, displayed on e bank U according to the setting of the register 90. Owing to the restoration of register 60, a new signal may then be transmitted and registered. The register 70 which now holds the " first " indication may then be restored by further operation of the cancelling switch 137. A circuit is closed over the wiper 126H and the " homing " contacts 73 for stepping magnet 71 and the switch is automatically restored. Simultaneously due to the operation of relay 134 the indications of the lamps T, U are transferred to preceding banks and a fresh indication is displayed on the bank U according to the setting of the register 100. Furthermore register 70 is ready to receive a further signal. In this manner the indications recorded on the registers are successively, displayed on the lamps as the " first " indications are cancelled. Each bank of contacts of the switches 46, 126 has 25 contacts which are appropriately multipled to effect cyclic operation of. the registers 60 - - 110. Modified system.-Figs. 2, 3, 4 (not shown). In this arrangement the " normal switch at the transmitting station is eliminated and the transmitting apparatus is such that if the stepping switch associated with the keys P1 - - P24 is in a displaced position when a plunger is depressed the switch is first restored to normal without transmitting impulses to line and is then stepped forward by the appropriate number of steps so as to transmit the correct number of impulses. Further, an indicator is provided at the transmitter to indicate when the registers are fully occupied and the system is so arranged that if cancellation at the receiver is in progress and a transmitting key is operated, the corresponding signal is stored and reception by the registers is prevented until cancellation is terminated. Moreover if an indication is in process of reception and an attempt is made to effect cancellation at the receiver, cancellation is only effected when the reception has been completed. Each transmitting key operates three contacts one of which initiates restoration of the stepping switch to normal while the others respectively initiate the operation of an impulse relay when the switch is restored and mark a contact on the switch to terminate impulsing. If the register switches at the receiver are fully occupied, the line circuit is maintained open at the receiver so that when a transmitting key is operated, although the transmitting switches are restored to normal, further operation is prevented by a relay which connected in the line circuit remains de-energized and operates a " register full " indicating lamp. As soon as a register becomes vacant " the relay is energized and impulsing is initiated. Each register has an additional bank of contacts, the wiper of which when in normal position bridges the line circuit. During cancellation of an indication at the receiver the cancelling relay opens to line circuit to prevent reception of signals. Moreover during reception of signals a further relay bridges the line circuit in order to prevent interference between the signals and the cancelling operation. In one form of signal transmitter, Fig. 6, the keys P1 - - P24 are circularly arranged on the cover of a switch casing 233 and are in the form of spring-controlled press buttons P each of which has a conical shoulder 239 adapted to co-operate with a slot in a rotatable spring- controlled locking-plate 241. The buttons cooperate with contacts 246 mounted on a plate within the casing and the arrangement is such that upon depressing a button, the conical shoulder passes through its slot, the locking plate meanwhile being displaced and restored to lock the depressed button in the operative position. Depression of a further key again displaces the locking plate to release the operated key. The locking plate has a cam which during movement of the plate momentarily operates an auxiliary contact to ensure restoration of the stepping switches of the transmitter in the event of faulty operation of "initiating" contacts of the press buttons. Modified system employing relay-transmitting and registering equipments. Figs. 7 and 8. Transmitting apparatus. The selective transmitting apparatus comprises a plurality of keys P1a - - P4a adapted to control relays 259 - - 266 and corresponding contacts L1e - - L4e. When a key is depressed, the key mechanism momentarily closes contacts c<1>, and opens contacts d', closes the appropriate contact in the group L1e - - L4e and opens and closes contacts such as P3a,P3b respectively. Operation of contacts c<1> energize