Patent GB-1044728-A (GB)
Title: Improvements in and relating to devices for the supervision of the braking process of a train
IPC: B61L3/00
Filed: 1964-05-28
Abstract: 1,044,728. Automatic train control. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. May 28, 1964 [May 31. 1963], No. 22107/64. Heading B7N. In an arrangement for supervising the braking of a train in accordance with a predetermined braking curve, the braking path is divided into a series of sections each having a given upper and lower threshold of speed and means are provided for determining in which section the train is travelling, for giving a warning signal to the driver to increase braking if the train speed remains between the two threshold values after a predetermined distance in the associated section has been traversed and for automatically applying emergency braking if the warning is ignored or the train speed exceeds the upper threshold. On passing signal P at the commencement of the braking zone PD the driver operates a switch for a given period of time during which the pressure in the brake pipe is reduced to apply a given degree of braking to the train. During this period of time a signal S is applied to a gate 11 whereby pulses from a multivibrator 5 are applied to the input of a counter 6 which thereafter stores a number of pulses CR<SP>1</SP> proportional to the degree of braking. When the train passes point B, information signal InB is applied to the train which opens gate 2 whereby pulses InA from a tachometer generator on the train are applied to distancemeasuring unit 1. In addition, the information signal, which is indicative of the required reduction of speed, is applied to decoding device 1A. Distance information signals Id from unit 1 and decoded information signals It from device 1A are applied together with signal Ic, indicative of the type of train, to testing circuit 3 which determines the lower and upper thresholds of speed Lb1, La1; Lb2, La2 ... &c. in the different sections ZP1, ZP2 &c. Signals La, Lb indicative of these threshold speeds are applied with a train speed signal VR to a comparator 4 which supplies one of three output signals: ZI-train speed above upper threshold, ZP-train speed between the two threshold values and ZL-train speed below lower threshold value. During the period the brake switch was applied the train speed, curve cr, was in zone ZL hence via a gate 13, the total count in counter 6 was applied to a counter 7. When the train enters zone ZP2 its speed falls within the zone ZP hence signal ZP opens gate 15 and subtractive pulses are applied from the tachometer to counter 7. The count ck<SP>11</SP> in unit 7 thus reduces over the distance a until the train speed again enters zone ZL when gate 15 is closed and gate 13 is opened to return the count in unit 7 to the value in counter 6. If the actual speed curve of the train cr is less steep than the desired braking curve GS then the distance travelled by the train when its speed is in zone ZP in successive sections increases. Hence when the train is in zone ZP4 the subtractive pulses applied to counter 7 reduces its count to a value below K<SP>11</SP>m at which the counter supplies a signal AL which in conjunction with signal ZP opens a gate (not shown) to actuate a warning signal 9, in addition both signals are applied to a delay device 8 which after a predetermined period of time, allowed to enable the driver to increase the braking, operates an emergency brake F.U. The braking is increased by the driver by operating his braking switch for a further period during which a signal S is supplied to open gate 11 so that further pulses InM are counted into counter 6 and also in conjunction with signal ZP opens gate 14 so that these pulses are also applied to unit 7 whose count ck<SP>11</SP> increases above the minimum K<SP>11</SP>m and signal AL is cut-off. The arrangement proceeds in the manner described until the train speed is reduced to the required level of the end of the braking path. The Specification includes a detailed description of the operation of units 1A and 3 in response to different control signals received on the train from the trackside.