Patent GB-899347-A (GB)
Title: Improvements in or relating to automatic control systems for railway trains
Inventor: WILMOT DOUGLAS GEORGE KENNETH
IPC: B61L3/00
Filed: 1959-02-04
Abstract: 899,347. Automatic train control. RICHARD GARRETT ENGINEERING WORKS Ltd. May 4, 1960 [Feb. 4, 1959], No. 3939/59. Class 105. In an automatic control system for railways in which a receive element in a control circuit carried by a locomotive is actuated by thepassage of the locomotive over track permanent and electromagnets, the circuit operates signalling and braking means on the locomotive if it exceeds the speed limit set for a particular track section and when it passes a signal set at danger. Two track permanent magnets are used for speed control, spaced at a distance which is a function of the speed limit. On passing the first magnet the receive element releases one of contacts FR or RR depending on the direction of travel whereby relay J releases, releasing a relay A. Relay C operates and re-energizes relays A and J whereby relay C releases and relay B operates energizing two thermal relays TR1 and TR2 which operate in ¢ sec. and 2 secs. respectively. The closing of contact TR2 energizes relay E which cuts off the supply to the thermal relays and energizes relay D. The relays cool and when contact TR1 closes relay H is energized for the period of discharge of condenser CON and via its contact H2 energizes bell X and green lamp L4. When relay H releases the circuit resets. If the speed is excessive the second magnet is passed before the thermal relay TR1 has cooled to the temperature at which its contact closes and, relays A and J are again released energizing relay C which re-operates relay J. Since relay B is operated, relay A is not re-energized and solenoid valve V is released and applies the locomotive brake. In addition, horn S, red light L2 and counter N are energized and remain in this state until the driver operates a reset switch RES. Operation of the switch operates relay G which releases relay B and C and energizes relay A, this releases relay D and energizes relay F whereby the circuit for the brake valve V is re-established and the braking removed. Release of the switch resets the circuit. The track apparatus at a signal comprises two permanent and one electromagnet, the spacing between the permanent magnets is such that a second signal is received before relay TR2 energizes (2 secs.). On receipt of this signal relays J and A release, relay C operates re-energizing relay J and the circuit of the brake valve V is broken at contact A2 and the brakes are applied. In addition, horn S and red lamp L1 are energized, relay C releases and relay M operates. If the signal is at clear the electromagnet is energized and the third signal releases relay J whereby relay H operates, energizing relay G which in operating releases relays M and B and energizes relay J and consequently relay A. The horn S and red lamp L1 are switched off and the bell X and green lamp L3 switched on, relay F energizes and closes the circuit to brake valve V which energizes and removes the brake application. When relay H releases the circuit resets. If the signal is at danger the brakes, red lamp and horn remain on until the driver operates his reset switch.