Patent GB-406706-A (GB)
Title: Improvements in or relating to train describing or platform indicator systems
IPC: B61L25/04
Filed: 1932-09-02
Abstract: 406,706. Electric signalling systems. STANDARD TELEPHONES & CABLES, Ltd., GRIFFITHS, J. B., BROWN, A., and DUNN, R. H., Connaught House, Aldwych, London. Sept. 2, 1932, No. 24501. [Class 40 (i).] Train descriptions are transmitted over a two-wire line circuit in the form of a constant number of impulses certain of which are rendered " active " in accordance with the description to effect the selection at the receiver of corresponding storage relays. Successive descriptions are stored in separate registers and are visually indicated in the order in which they are stored. Means are provided at the transmitting stations for cancelling the last stored description, for deleting any stored description and facilitating the stepping-forward of subsequently stored descriptions. Moreover provision is made for replacing a description in any register or interpolating a new description between descriptions already stored. Transmitting apparatus, Fig. 1. A description is transmitted in the form of a multi-digit number which may be set up by operation of the appropriate digit keys 1-6. The operated keys energize corresponding relays in the group AR-FR which lock up over a " reset " key RS, operate a lamp indicator and energize a common relay PR. Moreover corresponding contacts in the group ar4-fr4 associated with a sequence switch are operated to determine the nature of the signal to be transmitted. " Start " key TRK is then operated and relays TRA, TR are operated the latter being locked over cam C of the sequence switch SSC. Relay TR operates X and clutch magnet of the switch which then rotates through one revolution. Relay X operates Y which releases the key relays ready for further operations and also the relay PR which extinguishes lamp NSL to indicate that signal transmission is about to take place. During rotation, the cams D, E, F of the switch successively associate contacts wr3-ar4 with the line wire b, so that positive impulses are transmitted for corresponding unoperated contacts while negative impulses are sent corresponding to those contacts operated by the key relays. The contacts xr3-wr3 correspond to keys CA, DE, RE and IN having special functions. In this manner a train of impulses is transmitted, each impulse of the train corresponding to a particular digit or operation which is rendered effective at the receiver by reversing the polarity of the impulse. Receiving apparatus. This apparatus comprises a pair of line relays IP, IR the former of which is responsive only to negative impulses while the latter responds to each impulse irrespective of its polarity. In response to impulses relay IR operates relays O, E in cyclic order in such a manner that O is operated and released by odd and even impulses respectively. This effects sequential operation of the relay chain CA-CL which controls a, corresponding group of relays LW-LA, particular relays in this group being operated in accordance with the receipt of negative impulses and the operation of relay IP to close contacts ip1. The selected relays in the group LA .... lock up and operate corresponding relays in the first storage group AA, BA .... which lock up over contacts sa1, xal. Operation of the storage relays effects the illumination of corresponding lamps in the first train indicator Fig. 2A, and also operates the transfer relays TAA, TA in order that the following description may be registered on the succeeding group AB, BB ... In this manner successive descriptions are received in the relay group LA .. LW and are registered in turn in groups AA, BA .... , AB, BB ...., AC, BC ...., to effect operation of lamps in the corresponding indicators. Cancelling " first " train indication and stepping forward subsequent indications. When the first train reaches the receiving station, relay TCF is operated manually or by track contacts to operate FS, which at contact fs3 initiates the operation of a relay chain SA, SAA .... SE, SEA. SAA first operates followed by SA, when track relay contact tcf2 is operated, relay SA then energizing SBA followed by SB and the cycle is repeated in this manner throughout the chain. Relays SA, SB .... release the storage relays of the corresponding groups at contacts sa1, sb1 ... and at contacts sa2, sb2 ..... closes circuits so that the descriptions held in succeeding storage groups are transferred forward to the preceding groups. In this manner the second description is displayed as a " first " train indication and so on for subsequent descriptions, the last used storage group being freed ready for reception of the next transmitted description. Operation of the final relay SE releases relay FS. Cancelling last transmitted description. Depression of a " cancel " key CA at the transmitting station renders active the 4th impulse of the code so that relay LX in the group LA .. LW pulls up to operate a relay in group XA .. XE and corresponding to the storage group last occupied. This relay releases the associated group and effects cancellation of the corresponding indication, the relay TA, TB &c. of which restores to ensure that the next description sent in is stored in the released storage group. Deletion of any description. This is accomplished by operating the delete key DE and setting up on the keys 1 ...6 the description it is desired to delete. In the storage groups chain contacts aa3, ba2 ..., , ab3, bb2 .... &c. are set in accordance with the settings of the groups. Upon arrival of the " delete " code relay LY together with relays in the group LA .. LF corresponding to the description to be deleted are operated, the latter relays operating further corresponding chain contacts la3, lb3 ... , la4, lb4 &c. in such a manner that at the particular storage group affected the chain circuit is completed to effect operation of a relay in the group XA .. XE, which effects release of the storage group. Relay LY operates FS and thereby initiates the operation of the chain SA .. SE from a point corresponding to the affected storage group in order that subsequent descriptions may be stepped forward to fill the blank position. Replacing a description in any storage group. Operations of the replace key RE and keys corresponding to the description to be replaced effects, at the receiver, operation of the corresponding relay in group XA .. XE to unlock the storage group. The next incoming description is then stored in the released group. Interpolating a description. A description may be inserted between descriptions already stored by setting up a description on the keys 1 ... 6 corresponding to the stored description which is to follow the interpolated description and operating the key IN. At the receiver, relay LW as well as the description relays LA .. LF are operated. Relay LW switches over the chain contact circuits from relays XA, XB ... to relays WA, WB ... and a relay in the latter chain is operated. Relay LW operates TCB and BS which initiate operation of the chain SA .. SE in the reverse direction. These relays run off up to a point determined by the energized relay in group WA, WB ... and thereby effect release of the associated storage groups which take up the descriptions of preceding groups over contacts such as wb2, sb3, aa3 ..... wc2, sc3, ab3 &c. At the selected register group, the group does not take up the description of the prior group owing to the operation of the associated W relay which opens contact such as wb2. The next description received is then routed to the idle register. A description which has been held in another describer, e.g. one relating to a different track, may be interpolated in the first position in a manner similar to that previously described by operation of relay TCB which may be controlled manually or from the track. Relay TCB causes backward stepping of the chain SA .. SE the descriptions being thereby stepped backwardly to free the first storage group which then takes up the new description as determined by the contacts aq, bq .. fq. Modification. The relay chain SA ... SE may be replaced by a sequence switch. A plurality of receiving stations may be connected in parallel to the line wires in the manner described in Specification 366, 919.