Patent GB-523762-A (GB)
Title: Improvements relating to point and signal control systems for railways and the like
IPC: B61L21/06
Filed: 1939-01-14
Abstract: 523,762. Railway point and signal control systems. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and VENNING, C. F. D. Jan. 14, 1939, No. 1284. [Class 105] In approach locking arrangements for railways wherein the points in a route governed by a signal are locked against operation if the approach track section leading to the signal is occupied and the signal or route lever has been set to reverse position permitting traffic along the route, and the signal is controlled independently of track circuits, an approach locking relay is provided which, when energized, effects release of the locking if the signal is at danger, the relay being normally de-energized when the signal or route lever is in normal position for no traffic along the route, and being re-energized only when the signal or route lever is in its reverse position and a selected track section beyond the signal is occupied by a train or vehicle. Fig. 1 shows a length of track comprising an approach section A with signal 1S, and point sections B, C, D leading to exit section E, the points being in normal position for a through route (R1) from A to E. As shown, all the routes possible by reverse setting of the points 4, 5, 6 may be controlled by a single signal, or separate signals may be provided for these routes. Figs. 2, 3, 4 respectively show, for route (R1) the circuits of signal control relay 1HR energized to give a "proceed" signal, de-energized to give a " danger " signal, the approach locking relay 1ANS, and the route setting relay 1LR. Relay 1LR as shown is of the type having normal and reverse windings 1LR(N), 1LR(R) controlled by corresponding manually operated switches 1LRPN, 1LRPR, the route being dissolved with normal energization and set up with the reverse. The relay 1LR is energized by direct current from the terminals of a rectifier LRJ supplied with A.C. from terminals BX, NX. The normal winding circuit includes a back contact of relay 1HR and, in parallel, front contacts of an approach section track relay ATR and approach locking relay 1ANS. The reverse winding circuit includes a series of relay contacts LRN closed when corresponding route-setting and locking relays of conflicting routes are in their normal setting. The pick-up circuit of relay 1ANS includes a front contact of relay 1LR(R) and a back contact BTR of a track relay in section B, de-energized when that section is occupied, contact BTR being bridged by a stick circuit including a front contact 1ANSF of the relay 1 ANS. The circuit of signal relay 1HR includes a manually-operated contact 1LRPR of the route-setting, switch (or alternatively, a separate switch independent of the route-setting switch) contacts 4KR, 5KR, 6KR closed when corresponding indication relays are energized, front contacts 6LR, 5LR, 4LR closed when the corresponding route-setting relays of the conflicting routes are in normal position, and front contacts 1LR(R) closed when relay 1LR is in reverse position. Route R1 is set up by operating switch 1LRP to energize reverse winding 1LR(R). Relay 1HR is thus energized if points 4, 5, 6 are in or operate to normal position. Relay 1ANS is energized by closure of its circuit contact 1LR(R) and entry of a train or vehicle into section B, and is maintained energized over its stick circuit when the train has left the section, so long as relay 1LR is in reverse position. The Specification gives further details of the operation, and modifications of the circuit of Figs. 2. 3, 4 to adapt the invention for use with a system in which the points and signals are controlled by levers.