Patent GB-549891-A (GB)
Title: Improvements in or relating to train describing signalling systems
IPC: B61L25/04
Filed: 1941-04-18
Abstract: 549,891. Train describing systems. STANDARD TELEPHONES & CABLES, Ltd., BROWN, A., and MULLARKEY, A. J. April 18, 1941, No. 12803. Divided out of 542,078. [Clase 40 (i)] A train describing receiver for displaying descriptions of individual locomotives in a train of locomotives comprises storage relays arranged in groups, one for each locomotive described, and in order that the descriptions of locomotives may be removed, chains of contacts of "group occupied" relays are arranged to prepare circuits for short-circuiting the relays of the groups in turn commencing with the group corresponding to the first or last locomotive in the train. The transmitter and receiver described are similar to those of the system described in Specification 542,078 but modified to provide facilities for removing portions of a composite description of a single train. Setting up descriptions, Fig. 1.-Provision is made for 5 descriptions of coupled locomotives, storage being effected on the relay groups on the right of the Figure. On pressing one of the 5 description keys, SAK .. SEK, the corresponding key relay, say SB, operates the second relay BB in the first storage group, whereupon BM in the series holding circuit opens the operating circuit of the key relay, when SB has been released, and energizes UB which extends the set-up circuits to the second storage-group. UB operates its relief UBA (not shown) which restores the.key relay operating circuit. Further descriptions are set up in a similar manner and, if an error is made, all set-up descriptions may be cancelled by key RK. When the first description has been stored, BM starts a self interrupting relay group W-Y, Fig. 3, which flashes lamps (not shown) until the transmitted description has been received and checked back. Transmission.-The descriptions are sent as a train of 25 impulses, 5 groups of 5, a particular description in any group being signalled by a reversal of polarity of one of the impulses. The transmitter Figs. 2 and 3, is substantially the same as that described in Specification 542,078, the sequence switch SM being provided with an increased number of positions to accommodate the longer code. In the present case, the checkback pulse operating RC and RCA on completion of reception, opens the circuit of the lamp flashing relays W-Y and the lamps are steadily illuminated. When the descriptions at the receiver have been cleared out, a back pulse of opposite polarity operates CO which releases the storage groups and other operated relays. Reception.-At the receiver, Fig. 4, the impulses are counted on the chain CA, CB &c. and, if of reverse polarity, operate corresponding lamp display relays AA, AB &c. The last mentioned relays are arranged in groups of 5 with separate holding circuits controlled by series (group-occupied) relays MA .. ME. If the complete code is received, counting relay CAB operates OK followed by OKA which completes the lamp circuits. Relay COM also pulls up. Clearing out descriptions.-The first description is cleared by operating key COKI whereupon CRG(1 ) energizes followed on release of the key by CSR (1) which then releases slowly. During the operation of CSR (1) any operated relay AA .. AE in the first group is shunted down but the group relay MA is held over a second winding. When CSR (1) relapses, MA falls back and extends the clear-out circuit to the second group which, and subsequent groups, may be cleared out in similar manner. The descriptions may be cleared out in the reverse order by key COK (2) and relay CSR(2) in similar manner. When all descriptions have been cleared out, COB pulls up due to the release of all the group relays and OKA falls back. Relay COB applies to the line a pulse of polarity opposite to that of the check-back pulse to release the transmitter. Cancellation by the transmitting operator.- Before transmission has commenced, cancellation of the stored description is effected by key RK. Afterwards, the key is shunted by contacts of LO operated by the transmitting key TK and start relay TS, Fig. 2. Cancellation is then effected by operation and release of key CAK which operates CAN whereupon TS is operated to start transmission of the code which will now have the polarity of the 26th impulse reversed due to the operation of contacts CAN3. At the receiver, code relay AAB pulls up followed by CAR which energizes a buzzer and lamp (not shown). The receiving operator cancels the whole description by operating and releasing key KAK whereupon relay KAN releases the description storage relays. and the clear-out signal is sent back.