Patent GB-392939-A (GB)
Title: Improvements relating to railway traffic controlling apparatus
IPC: B61L3/12
Filed: 1931-11-26
Abstract: 392,939. Railway signalling systems. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross, London.- (Assignees of Nicholson, F. H. ; 1424, Walnut Street, Edgewood, Pennsylvania, U.S.A.) Nov. 26,1931, No. 32823. Convention date, Feb. 2. [Class 105.] An automatic system for giving a brake application and cab signals on a train comprises at the entrance to each section an inert inductor core P<4> .. initiating a brake application which is cancelled as the train passes an inductor loop Q<4> .. if the loop is energized by current of a predetermined characteristic assumed in dependence on the traffic conditions ahead. If the loop is de-energized or energized by current of a different characteristic, these conditions respectively arising if the section or the section in advance is occupied, the braking can be cancelled by a manual operation, but danger or caution lamp signals remain lit. Fig. 1 shows the track apparatus and Fig. 2 the train apparatus. The track relays T<4>.. are polarized and the track current is controlled by the usual automatic wayside signals S<4> .. so that a reverse current is supplied to the section in rear of an occupied section. The loops Q<4>.. are supplied with alternating current over contacts 7, 8 of slow-release track repeater relays U<4>... Under clear conditions this loop current is an interrupted one due to make and break relay V<4> .. being supplied over the contact 9 of the rearward track repeater relay U<3>.. which is dropped by the oncoming train. Under caution conditions the track relay contact 12 being at reverse de-energizes the make and break relay V<4> . , so that alternating current is supplied continuously to the loop over back contact 11 of such relay V<4>. Under danger conditions the loop is void of current since the track repeater relay contacts 7, 8 are dropped. The train apparatus comprises a core 37 with a primary winding 30 and a secondary winding 31 connected to a relay R which drops its contact 29 when a track core P<4>.. is passed and so cuts off the supply line X from the core winding 30 and brake magnet M. The contact 29 of relay R can be restored and then maintained through the stick connection from such contact by a manual operation of a pneumatic cancelling device 33, but is automatically restored if the loop Q<4>.. is energized with the interrupted alternating current. The loop current acts inductively on a receiver C<2> of the continuous inductive type which energizes a relay E through an amplifier D. The interrupted current will cause the energization of two slow-release relays A, B by the lifting and dropping of contact 13 of relay E. The closing of contacts 19, 16 of the relays B, A energizes a relay H over back contact 25 of the cancelling device 33 so that the relay R is picked up over contacts 18, 15 of the relays. B, A, back contact 26 of device 33, and contact 28 of relay H. A clear lamp 34 is temporarily lit over contacts 18, 15 so long as the receiver C<2> is being influenced. If the loop is energized continuously with alternating current then the contact 13 of relay E remains lifted so that the relay A only is energized. The device 33 must. be operated to cancel the braking ; this is. effected by the front contact 25 of the device 33 energizing the relay H so that the relay R is then energized over front contact 26 of device 33 and front contact 28 of relay H. The front contact 27 of relay H picks up a relay BP over front contact 14 of relay A and back contact 17 of relay B ; this relay BP is held by a stick circuit over its own contact 22, a contact 24 of a device F (closed by the brake fluid-pressure), and back contact 27 of the relay H which drops as soon as the relay R is energized. The relay BP maintains a caution lamp 35 lighted over its front contact 23. If the loop is de-energized then the contact 13 of relay E remains dropped and relay B remains energized. To prevent a brake application the cancelling device 33 must be operated to energize the relays H and R as before ; the energization of relay H opens the stick circuit of relay BP and now a danger lamp 36 remains lit over back contacts 23, 21 of relays BP, AP.