Patent GB-665483-A (GB)
Title: Improvements in or relating to electrical signalling systems
Inventor: PREIST THOMAS PHILIP
IPC: E21F17/18
Filed: 1949-05-05
Abstract: 665,483. Electric selective signalling. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. April 11, 1950. [May 5, 1949] No. 11983/49. Class 40 (i). In a signalling system for use on a train in a mine-haulage system, visual indications are given to the driver in response to "stop", "goinbye", and "go-outbye" signals initiated by the conductor and also in response to an "emergency stop" signal which may be initiated by the conductor, or from any truck automatically when a portion of the train becomes detached. The "stop" indication may be cleared down only in response to a countermanding signal from the conductor but the other signal indications may be cleared by the driver prior to the carrying out of the instruction. The visual signals are preferably supplemented by a bell which may also be used for further code signalling by the conductor to driver. The relay apparatus shown is located on the locomotive and connected by lines extending the length of the train from terminals T1, T2, T14 to keys KA, KB operable by the conductor. The "stop", "go-inbye" and "go-outbye" signals are given by the conductor closing the key KA once, twice and three times respectively. Operation. Upon closure of key KA a relay L is operated which rings the driver's bell CB, operates a slow-to-release relay N and a slowto-operate relay P in turn, and energizes a relay A to light the stop lamps SL. Upon release of the key, ringing stops and relay A locks in series with relay B over L3, A2, L2. If the initiated signal is "stop", relays N, P, release after a period and relays A, B remain operated with the "stop" lamps lighted until a further signal is initiated by the conductor. If the next signal is "go-inbye" relays N, P energize as before at the first ring operation of relay L and remain operated for the period between the two rings. Relays A, B are released at contacts L2 as relay L pulls up. Relay A however immediately reoperates and at the end of the first ring locks in series with relay B as above described. Relay A lights the "stop" lamps SL as before. As relay L operates to make the second ring, relay A releases to extinguish the "stop" lamps, but B holds and at the end of the ring, locks in series with a relay C over L3, A2, key KD, B2, L2 whereby the "go-inbye" lamps GIL are lighted at the subsequent release of relay P. If however three rings are made for "go-outbye" the third ring is made before P releases and causes B to release as the third ring commences. Relay D operates in series with C at the end of the ring so that when subsequently P releases the "go-outbye" lamps GOL are lighted. The "go-inbye" and "go-outbye" lamp indications are extinguishable by the driver operating his "go-signal cancel key" KD which opens the locking circuit of the operated pair of relays A, B, C. Further code signalling may be effected by the conductor closing his key KA a number of times in excess of three, sufficiently rapidly to keep relay P operated. At the fourth ring relay C releases but, relay D remains locked over P3, D2, to prevent actuation of any of relays A, B, C and so prevent lighting of any lamp indications. The code signalling is effected entirely by the bell CB. At the end of such signalling relay D relapses as P falls off, to normalize the equipment. "Emergency stop" signals. This is effected by the closure of key KB by the conductor, by closure of a key such as KB located on any of the trucks, or by bridging terminals T2, T14 automatically when a portion of the train becomes detached. The emergency stop relay ES is thereby operated, locks over key KC and lights the emergency stop lamps ESL. The relay ES also rings the bell CB and energizes relay A to light the stop lamps SL. The driver may cancel the emergency stop indication by opening his "emergency stop cancel" key KC but the stop lamps remain lighted as for a stop signal until a further signal is initiated by the conductor.