Patent GB-767732-A (GB)
Title: Railway signalling equipment
IPC: B61L19/06
Filed: 1954-04-23
Abstract: 767,732. Railway signals. STANDARD TELEPHONES & CABLES, Ltd. April 23, 1954 [May 2, 1953], No. 11793/54. Class 105. In a railway signalling equipment for a line such as a station track having an exit signal operable when an exit route has been established from the line and an entry signal operable when an entry route to the line has been established and when the exit signal has been restored to a normal imoperated condition after a previous operation, in order to prevent inadvertent operation of the exit signal this latter is operable only after an exit route has been established and either an entry route has been established as in the case of a through route, or the identity of the exit route has been confirmed as in the case of a train starting from the station. In the platform line shown in the upper part of the Figure, trains run from left to right. Assuming both entry signal E and exit signal A are unoperated, i.e. showing a red light in lamps Le rt, La rt respectively with relays Re1 and Ra1 operated, and therefore with contact Ra2 in the circuit of the entry signal control relay Sel made to establish an exit route control board, push buttons Ta, Ts are operated and at front contacts Ta2, Ts latch-type relay Fa1 is picked up to cause establishment of the exit route whereupon contact Ua is made, indicating such establishment but the circuit of green lamp La gn is still open at contact Sa3 and this signal cannot be operated until the exit signal control relay Sa1 is picked up either at front contact Se4 of entry signal control relay Se1 or by the confirmatory key contacts Ta1, Tg. To establish an entry route push buttons Te, T1 are operated to pick up the latch-type relay Fe1 over front contacts Te2, T1, to cause the establishment of the route whereupon front contacts Ue are closed to indicate such establishment. At front contact Fe2 relay Se1 is picked up and held over its front contact Se2. At front contacts Se3, Ue and Fe3 the green lamp Le gn is lighted and relay Ge1 is operated. At back contact Ge2 the red lamp Le rt is extinguished. At front contact Se4 relay Sa1 is operated and at front contact Sa3 the green lamp La gn is lighted followed by the extinction of the red lamp La rt. To start a train from the platform line, the exit route is established as before and confirmatory push buttons Ta, Tg are operated to close an operating circuit for relay Sa1 over front contacts Ta1, Tg and Fa2. Relay Sa1 is held over its front contact Sa2. At front contact Sa3 the lamp La gn is lighted over front contacts Ua and Fa3 and relay Ga1 is operated. At back contact Ga2 relay Ra1 is released and the red lamp La rt extinguished and at front contact Ra2 the pick-up circuit of relay Sel is opened so that the entry signal cannot be operated and the red lamp Le rt will remain lighted. The button Tg may be used in common for exit routes from other platform lines, or additional buttons may be provided so that the establishment of an exit route as part of a through route requires the operation of different buttons from those used to establish the exit route for the start of a route from the line.