GB972859A - Improvements in or relating to train control apparatus - Google Patents

Abstract

972,859. Automatic train control. SOC. INDUSTRIELLE DE LIAISONS ELECTRIQUES. May 5, 1961, No. 16456/61. Heading B7N. In a train braking control apparatus utilizing the arrangement disclosed in Specification 971,823 by means of which a train passing point BA at the commencement of a braking zone when signal Si is set to stop, is brought to a halt at point C by a counting and comparing system which prevents the train speed exceeding a safety speed defined by curve I, means are provided: (a) when signal Si shows a reduced speed aspect for automatically reducing the train speed to 60 km./h. at point E; (b) when a stop signal showing when a train passes point BA is changed to a reduce speed aspect, for causing the train to stop braking according to curve I and proceed at a constant speed for a predetermined distance and then brake according to curve II; (c) when a clear aspect changes to stop after the train has passed BA, for immediately applying the brakes to bring the train speed below the safety speed defined by curve I; (d) for checking the operation of the apparatus if the signal Si is clear. The control apparatus includes track beacons BA, BB which pick up train relays MA, MB, respectively, on passage of the train thereover and relays FR, FR2 which are energized by " reduce speed " and " clear " track tones, respectively. In the operation (b) above, the train passes beacon BA when the signal Si is set to stop (no track tones transmitted) and the counting and comparing apparatus disclosed in Specification 971,823 and shown as Ch. No. 1 in Fig. 3 is brought into operation and the train is braked according to curve I. Furthermore a second counting apparatus Ch. No. 2, Fig. 4, comprising units N1, N2-Nq, is operated by a pulse generator IN, coupled to the train wheels, to produce a count representing the distance travelled after passing point BA. At some point, say x, the signal aspect is changed to reduce speed and the corresponding track tone picks up relay FR on the train. On passing beacon BB, relay RA is picked up by the momentary energization of relay MB, relay RC is picked up for a short period by the discharge of capacitor CC and energizes relay RD which is held over contacts rd1 and re1. The opening of contact rc2 restores the upper part of counting apparatus Ch. No. 2 to zero but the count is stored in the lower section of the apparatus in the energized relays L1-Lq which are held over relay contact maS. In addition pick-up of relay contact rd2 stops the count in Ch. No. 1. The train then proceeds at the speed determined by the last count in Ch. No. 1 and the upper part of Ch. No. 2 continues counting for a distance a, equal to the distance between the beacons, when the count in the upper part of the chain equals that stored in the lower part of the chain. When equality is reached relay RE energizes and releases relay RD and the count in Ch. No. 1 continues and the train is braked along curve II until it reaches the required speed (say 60 km/h.) at point E. Specification 804,427 also is referred to.