GB921716A - Automatic track brake control - Google Patents

Abstract

921,716. Retarder control systems. ETABLISSEMENTS SAXBY. March 17, 1960 [Nov. 19, 1959], No. 9415/60. Class 105. An automatic control system for a track brake comprises a row of magnetic detectors spaced along the brake so as to produce electrical pulses on passage of a vehicle wheel, and are arranged in successive groups I, II-N, Fig. 4, the length of each group being less than the least distance between succeeding wheels of a vehicle, the groups II-N being connected successively by a rotary switch 27 under control of a frequency divider 22, dividing the impulses from the groups by the number of detectors in a group to a comparator of the type shown in Fig. 3, whilst the first group I is connected to a similar comparator 23, the output of which on the passage of a wheel is used both to reset the switch 27 to its initial position for connecting group II to the comparator 24 and also, for measuring the speed of the wheel and where the speed of the vehicle is at or below a predetermined speed, to release the brake. The even numbered detectors of a group are connected to amplifier 6, Fig. 3, and the odd numbered detectors to amplifier 5 of a speed measuring comparator, the outputs of the amplifiers being fed in opposition to a vibrating relay 7 so as to connect a source 15, through safety resistance 26 and alternating contact 20 of relay 7 to condensers 16, 17 connected across windings 13, 14 of comparator relays 8, 9 so that their discharge currents through windings 13, 14 oppose a reference current i in windings 10, 11, representing the predetermined speed of the vehicles passing through the brake, at which the brake should be released, the current i being adjustable by variable resistance 25. When current i is neutralized, the predetermined speed of the vehicle having been attained, a signal current is applied over contact 18 or 19 to terminal 21 which controls the release of the brake.