GB456909A - Improvements relating to block signalling systems for railways and the like - Google Patents

Abstract

456,909. Railway signalling instruments. ROBERTS, W. S., Newby, Ruff Lane, Ormskirk, Lancashire, BURTON, J. H., Pine House, Signal Works Road, Fazakerley, Liverpool, and RAILWAY SIGNAL CO., Ltd., 40, Broadway, Westminster. May 28, 1935, No. 15499. [Class 105] Alternating currents of different frequencies are used singly or in combination to transmit the different block signal indications. Other frequencies may be transmitted for lock-andblock working. Upper and lower indicators on each instrument serve for the up and down lines. For the passage of an up train from A to B the signalman at A requests acceptance by a bell signal whereupon the signalman at B sets his commutator 11B to the " line clear" position 13B and depresses his plunger 15B to close contacts 18B. This action applies a battery 28B to a vibrating relay 92B which has a weighted spring 20 to give a predetermined frequency and the spring of which alternately applies direct current to the opposite halves 24, 25 of a primary winding 26 thereby to induce current of the predetermined frequency in a secondary winding 27 which feeds the line wire 2 over the depressed plunger contacts 19B. At the instrument 1A this current passes by the plunger contacts 16A to selector devices S1A, S2A, S3A, but only the device S2A responds to the particular frequency. The selector devices each consist of a weighted spring 30 acted upon by electromagnets 31 and thus only for the proper frequency current will the movement of armature 29 be sufficient to close contacts 32, 33. The response of the device S2A rings the bell 34A and effects the energization of the winding 6A whereby the " line clear " block signal is given on the upper indicator 3A. At the accepting station B the upper indicator 3B shows the particular block signal transmitted therefrom, for instance by the intermediary of a winding 9B energized at the same time as the vibrating generator relay G2B ; alternatively, this indicator 3B may be actuated mechanically from the commutator 11B. The other block signals are transmitted by different frequency currents and indicated in a similar manner, those for the down line trains from B to A being shown on the lower indicators 4A, 4B and the particular frequency currents being transmitted from the station A which is the accepting station for the down line traffic. The bell signals are given by the plungers 15A, 15B but without changing the position of the commutators 11A, 11B. Such bell signals are given from A when the train enters the section at A, the operator at B then effecting the change over of the instrument indications to " train on line." When the train leaves the section at B the operator at B effects the change over of the instrument indications to " line closed."