Patent GB-372293-A (GB)
Title: Improvements relating to railway traffic controlling systems
IPC: B61L23/16
Filed: 1931-02-03
Abstract: 372,293. Automatic railway signalling systems. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Street, King's Cross, London.-(Assignees of Failor, C. W. ; 776, Lenox Avenue; Forest Hills, Pennsylvania, U.S.A.) Feb. 3, 1931, No. 3422. Convention date, Feb. 18, 1930. [Class 105.] Relates to an automatic railway signalling system in which wayside or train carried signals are controlled by interrupted or code currents supplied to the track circuits. According to the invention each track section is provided with two or more decoding relays the energizing circuits of which are tuned so that each is responsive only to a particular code (frequency of interruption of the current) current in the track rails and these relays select the wayside signals and the particular code current to be supplied to the rear section. The track relay of the section operates its armature .at the code frequency to supply current to the decoding relays except when it. is de-energized by the presence of a train. In the system shown the electric powerfor section UV is provided by a transformer. L<u> which supplies a transformer M" having a winding 9 for the lamp signals S<u> and a winding 8 with rectifier 10 to give direct current which is interrupted by the track relay armature 13 at code frequency and so by means of windings 11, 12 of a transformer F<u> energizes, through reactances 34 and rectifiers 15, the relays H, D, DD, the circuits to the two latter of which include condensers and are tuned so that relays D, DD only respond to their particular interruption frequency while the relay H responds to all the three frequencies used. The supply transformer L<u> also energizes one winding,of the track relay T<u> and a motor 38 which drives the coding discs K<u> over one or other of which interrupted current passes to a track section feed transformer C<u>. When a train Z occupies section XY the track relay T<x> permanently drops its contact 13 so that the current from rectifier 10 passes through the left half of transformer Fx and not being interrupted does not influence the winding 12. The relays H, D, DD are therefore de-energized so that at signal. S<x> red lamp RA is lit over back contact 20 ; lamp RB over back contact 19 ; and over back contact 21 alternating current of interruption frequency 80 per minute passes to the transformer C<x> supplying rear section WX. In section WX, therefore, the track relay. T<w> is energized to operate 80 times per minute so that the circuits to relays H, D, DD are fed with current but only relay H responds so' that at signal S<w> lamp YA is lit over front contact 20 and back contact 24 ; lamp RB over front contact 19 and back contact 22 ; and over front contact 21 and back contacts 23, 25 current of interruption frequency 120 per minute passes to the transformer C<10> supplying track section VW. In section VW the track relay T<v> operating at 120 times a minute causes relays H and D to respond so that at signal S<v> lamp YA is lit over front contact 20 and back contact 24 ; lamp GB over front contacts 19, 22 ; and over front contacts 21, 23, code current of interruption frequency 180 per minute passes to transformer C<v> supplying track section UV. In section UV the track relay T<u> operating at 180 times a minute causes relays H, DD to responds so that at signal S<u> lamp GA is lit over front contacts 20, 24 ; lamp RB over front contact 19 and back contact 22 ; and over front contact 21 back contact 23 and front contact 25 code current of the same interruption of frequency 180 is supplied to the section (not shown) in the rear so that the signals in sections to the rear of UV are the same as those in UV. The current in the track rails could act inductively on train carried relays similarly selecting a cab signal.