GB1032383A - Improvements in and relating to electronic arrangement for the automatic control of rail brakes - Google Patents

Abstract

1,032,383. Retarder control; vehicle speed determination. SAXBY. March 26, 1964 [March 27, 1963], No. 12806/64. Heading B7N. In an arrangement for releasing a retarder in a railway classification yard when the speed of a vehicle being retarded has been reduced to a desired value, the vehicle speed is determined by the time intervals between signals generated by a number of equi-spaced wheel detectors positioned adjacent the retarder track. The wheel detectors C are formed in groups 01, C2 &c., each of which is connected via a gate P1, P2 &c., and amplifier 4 to a bi-stable circuit 3 and a counter 6. The counter, the " return to zero " circuit 7 and decoder 9 act to control the gates P1, P2 &c., so that once the rear wheel of the vehicle enters the retarder only signals generated by this wheel are applied to the bi-stable circuit. This circuit, Fig. 5, opens when switched to one of its stable states a gate P10 which controls the passage of pulses from oscillator 13 and pulse former 14 to a counter 12 and when switched to its other state controls the passage of the pulses to a counter 12<SP>1</SP> via gate P10<SP>1</SP>. When the number of pulses counted in a switching sequence increases to a predetermined value, which is a function of the required release speed for the vehicle then the decoder, e.g. 31 associated with the counter energized during that sequence emits a signal which via a register 41 is applied to one input of a coincidence circuit 38. If, during the next sequence, the number of pulses counted in the other counter reaches the predetermined number then a signal is applied via register 41<SP>1</SP> to the second input to the coincidence circuit which then generates an opening signal for the retarder. Ensuring coincidence between the counts in successive switching sequences prevents mis-operation due, e.g. to wheel bounce. Further apparatus described in Specification 1,032,382, is provided which modifies the predetermined number in accordance with the deceleration of the vehicle and the time lag in operation of the retarder to ensure the vehicle leaves the retarder at the required speed.