Patent GB-428688-A (GB)
Title: Improvements in electrical signalling systems
IPC: B61L25/04
Filed: 1933-11-10
Abstract: 428,688. Electric signalling systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, and GREGORY, H. J., 35, Merriman Road, Blackheath, both in London. Nov. 10, 1933, No. 31399. [Class 40 (i)] In an electric signalling system, more particularly for signalling trains description, of the type wherein successive signals are stored and displayed in turn at the receiver, the signals are transmitted in the form of impulse trains and the receipt of each impulse at the receiver brings about the insertion of a resistance into the line circuit to form a check upon its effective receipt. Fig. 1 shows the apparatus at the control station and Fig. 2 that at the substations, the equipment being arranged for the storage and display of a plurality of train descriptions. Each description is transmitted as a train of impulses over the line loop TL1, TL2, the number of impulses in a train being determined by the operated key in the group 1DK .. 9DK. Successive descriptions are stored on switches SA .. SF, three of the stored descriptions being displayed on the lamp boards 1CAB, 2CAB, 3CAB. Upon passage of the train corresponding to the description on 1CAB, the description is cancelled and the remaining descriptions are automatically advanced through the lamp boards and a waiting description is displayed on the freed board. Auxiliary indicators 1SL, 2SL, 3SL are automatically operated to display platform or stopping place information. Transmission of a description. The switch T, Fig. 1, normally occupies a position corresponding to the last description transmitted and when a key in the group 1DK .. 9DK corresponding to a new description is depressed, the key off-normal contacts kon are operated to pull up relay K and mark the appropriate contact in bank t1. Key release magnet KM also is included in circuit with K but is not energized. Relay K initiates the self-stepping of switch T which steps to its zero position and pulls up relay B. Relay B prevents further self-stepping and releases relay K and completes the line circuit over the line relays HA, D. Relay HA operates LA which prepares a stepping circuit for switch magnet TDM and relay D at the substation operates stepping magnet SADM in the event that no descriptions are stored), in series with relay O which, however, remains de-energized until the interrupter contacts sa are opened, when P pulls up and opens a short-circuit across a winding of the line relay D so as to increase the line resistance and cause release of HA. Release of HA operates TDM and relay A which opens the line circuit. This releases D and in consequence, SADM is released and the switch SA is stepped. P also is released to again shortcircuit the winding of D while at the control station, A is again released to re-establish the line circuit and allow the transmission of a second impulse. This cycle of operations is repeated at each impulse and the switch SA is stepped until the wiper t1 engages the marked contact, when relay K is pulled up to open permanently the line circuit. Release of HA operates KM which releases the operated description key. Upon the final release of D at the substation, switch SA takes its final step and relay R which is maintained energized during impulsing, is released to operate magnet SDSDM and step the switch SDS one step so as to associate the next storage switch SB with the receiving relay. The next description to be transmitted is stored on SB and subsequent descriptions are stored in succession on SC .. SF, the switches being connected up in succession by switch SDS. The appropriate lamp in the bank 1CAB is illuminated in a circuit including wipers dc1, sa2 and relay G. Relay G closes a self-stepping circuit of switch DD which steps until wiper dd1 picks up the marked lamp lead when L pulls up and stops the switch. Switch DD operates a platform or route lamp indicator 1SL, the bank contacts being connected to a link frame DP in order that the indications to be displayed may be changed at will. A switch similar to DD is provided in association with each display indicator so as to operate a corresponding number for auxiliary indicators. When the available storage switches are fully occupied, relay RF is operated and line relay D is disconnected while maintaining the line circuit for HA. This prevents the transmission of any further descriptions, operation of a further destination key merely causing switch T to step to zero and in that position cause lamp LL to light. Cancellation of " first " train indication and transfer of succeeding indications. Operation of the " cancel " switch TS manually or by the train operates relay F which energizes stepping magnets DCDM, SADM, the latter over the wipers dc4, sa1. Switch SA self steps to zero, de-energizing F and DCDM and stepping switch DC one step to free the switch SA and transfer the indications held on switches SB, SC, SD to the lamp indicators. Relay F also releases G which drives DD to normal. Upon re-operation of G, DD is caused to line up with the new lamp indication displayed by 1CAB. Cancelling previously transmitted signal. This is effected by operation of a " cancel " key CAK which connects relay CA across the line TL. When a display is completed and a relay such as G is operated, relay RE is operated to reverse battery potentials applied to the line. This reversal together with operation of key CAK pulls up CA which energizes C, K and causes the switch T to drive to normal. The key CAK also marks the second bank contact of T so that two impulses are then transmitted to select relay CN over the wipers of the storage switch subsequent to that containing the signal to be cancelled. Relay CN closes self-stepping circuits for the two switches over wipers sds3, sds5 and these switches step to zero. Magnet CASDM also is energized and, upon release of CN when the switches reach zero, moves one step to operate XB. Relay XB interacts with CASDM and simultaneously drives SDS until CA had taken a fixed number of steps sufficient to drive the switch SDS into engagement with contacts associated with that switch from which a signal is to be cancelled. Repeating. Signals may be repeated to a further substation over lines OG by a contact of relay P.