Patent GB-971823-A (GB)
Title: Improvements in or relating to train control
Inventor: MALAQUIN ANDRE
IPC: B60L7/00
Filed: 1961-04-28
Abstract: 971,823. Automatic train control. SOC. INDUSTRIELLE DE LIAISONS ELECTRIQUES. April 28, 1961, No. 15514/61. Heading B7N. An arrangement for controlling the braking of a train over a braking zone whereby at the end of the zone the train comes to a halt or its speed is reduced to a desired value comprises pulse generating means which are energized as the train enters the zone to produce first and second trains of pulses the number of which are proportional to the distance travelled by the train along its track, first counting means to count the first pulses and to provide an indication of the difference between the number of pulses counted and the total number of pulses which corresponds to the length of the working zone, said difference being an indication of the safety speed or the speed the train should be travelling to stop safely or to have slowed down to the desired speed at the end of the zone, second counting means to count the number of second pulses generated per unit of time, the count being indicative of the actual train speed and comprising means for comparing said difference and the count representing actual speed to determine whether the speed is above the safety speed and to control train braking accordingly. The first pulses produced by a generator 12 coupled to the train axle are counted by the upper counting chain comprising units M 1  . . . Mq which open and maintain open in succession contacts a4(1) . . . a4(q) in the upper arm of parallel circuit X as counting proceeds. The second pulses generated at a higher rate by generator 13 which is also coupled to a train axle are counted by a lower counting chain comprising units N 1  . . . N q  which open in succession and maintain open contacts d4(1) . . . d4(q) in the lower arm of circuit X during the " on " period of a timing device H. The number of contacts which open during each timing period is a measure of the train speed and at the end of each timing period the counting chain returns to zero and the contacts d4(1) &c. close. The number of contacts a4(1) &c. in the upper row which are closed is a measure of the safety speed. It should be noted that contacts a4(1) &c. open in succession from the right of the Figure and contacts d4(1) &c. from the left. Lamps L 1  . . . Lq are connected between corresponding points on the two arms of the circuit X and the circuit is connected in series with a power source and a slow-to-operate relay K which on release actuates the train brakes. Assume the train has travelled sufficiently far into the zone to open the contacts a4(1) to a4(p) in the upper arm of the circuit then the number of remaining closed contacts, i.e. a4(q)-a4(p) represents the safety speed. If at this time the actual speed of the train is such that only four of the lower contacts open during the timing period of unit H then relay K is maintained operated via a circuit which extends along the lower arm to lamp Lp, through the lamp and via the closed contacts of the upper arm to the relay. If, however, the train exceeds the safety speed at least five of the lower contacts will open during the timing period and the above traced circuit will be opened at lower contact d4(p), the relay releases and the brakes are applied. The pick-up time of the relay is greater than a timing period of the unit H so that the train speed must be reduced below the safety speed before the relay re-energizes. The number of lamps which are continuously energized is a measure of how much the actual speed is below the safety speed.