Patent GB-971766-A (GB)
Title: Improvements in and relating to vehicle control systems
IPC: B61L3/22
Filed: 1961-09-11
Abstract: 971,766. Automatic train control. GENERAL SIGNAL CORPORATION. Sept. 11, 1961 [Oct. 24, 1960], No. 32500/61. Heading B7N. In an automatic train control system in which the speed of a train is controlled by coded track circuit currents, the train is decelerated to a halt at a station in accordance with a predetermined pattern by applying uncoded A.C. to the track circuit in approach to the station and by means which co-operate with pairs of coils which are positioned along the track and spaced whereby when the train is correctly following the pattern the time required to pass between any pair of coils is constant. The means time the passage between each pair of coils and decrease or increase the train speed if the time of passage is less than or greater than the constant time period. The arrangement is describedwith reference to a stopping section of track ST with a station platform. The track rails of the section are supplied with an A.C. signal at a distinct frequency via front contacts 32, 33 of relay ATP and this signal when picked up by coil RC4 on the locomotive is passed via filter 141 and energizes a relay TF and a synchronous motor CM. In addition, pairs of coils PC1, PC2 are positioned adjacent the track section and co-operate with coil RC1 on the locomotive to momentarily release a relay P each time a coil is passed. On passing the first coil of a pair relay P releases and initiates a timing sequence by releasing relay MP1 whereby a clutch EC operates and connects the synchronous motor to the drive for cams 29 and 30. Contact 117 is opened on each revolution of the cam 30 and causes actuation of a stepping switch SW at a constant rate until the release of relay P on passing the second coil re-energizes relay MP1 and releases the clutch. The number of operated V relays, which are energized via the stepping switch contacts, is indicative of the time taken for the train to pass over the distance between the coils. This number of operated relays determines the control exercised over the braking and power apparatus of the train, e.g. if relay T1V only is energized (train too fast) wire 54 of the locomotive braking apparatus LBA is energized and heavy braking is applied, if four of the V relays are energized (speed correct) wires 54, 59, 61 and 63 of the braking apparatus are energized and no braking is applied. If the train is travelling too slowly five of the relays are operated and a low speed wire 53 for the locomotive motor control apparatus LMGA is energized to increase the train speed. The spacing between each pair of coils is decreased progressively over the stopping section and in consequence the train speed diminishes until it comes to a halt at the station platform. The train apparatus also includes means for control of the train speed outside the stopping section e.g. in an approach section AT which is supplied with track circuit energy at either 75 (4-5 m.p.h.), 120 (10-12 m.p.h.) or 180 (30-32 m.p.h.) cycles per minute in dependance on the required train speed. This signal is picked up by coils RC3, RC4 on the train and applied via transformer 20 and code following relay CR to selective circuits 75DU, 120DU and 180DU whereby one of relays 75R, 120R and 180R is selectively operated and one of three motor speed control wires 53 (low), 52 (medium) or 45 (high) is energized via a front contact of the selected relay. Additionally the speed of the train is monitored and controlled by an arrangement including an axle driven generator FG which produces a signal at a frequency which is a function of train speed and is connected via a front contact of the selected rate relay to one of three filters 30-32 m.p.h., 10-12 m.p.h. and 4-5 m.p.h. each associated with a specific speed range. The arrangement includes further circuitry which acts on two relays CP and OS controlling the train braking and motor drive respectively to maintain the locomotive speed in the required range. When the train stops at the station platform an overlay track circuit OTR releases relay TR, which initiates a timing arrangement whereby after a predetermined stopping time a signal at a selected one of the code rates 75, 120 and 180 is applied to the line in order to restart the train. In a second arrangement, Figs. 2, 3A and 3B (not shown), the timing is performed by apparatus on the track and the train brakes and motor drive are controlled by selective signals picked up on the train from a series of loop circuits positioned throughout the length of the stopping section.