Patent GB-227029-A (GB)
Title: Improvements in or relating to automatic train control apparatus
IPC: B61L3/12
Filed: 1924-04-14
Abstract: 227,029. Richards, H. W. April 14, 1924. Electrical systems, automatic; track apparatus actuating signals on, and for stopping, trains.- In a system for giving signals in the cab corresponding with track conditions, and for stopping the train under danger conditions, the vehicle carries a transformer with a three-pole core 17, a primary winding 11, secondary windings 15, 16 connected in series and in opposition, and a secondary winding 12, the secondary coils being disposed on the poles as shown. Winding 11 is continuously energized by an A.C. generator G<1>. A three-pole core 18 situated on the track serves to complete the magnetic circuit as the vehicle passes, and has windings 9, 10 selectively closed or both open at contacts 7, 8 according to track conditions, the windings being on the poles which co-operate with the poles carrying windings 15, 16. This selective closing of the winding circuits determines the path of the magnetic flux, the greater flux being through the pole with the open winding. Winding 12 is in series with a contact 28 and winding 25 of a relay R, and with a secondary winding 14 of a ring transformer T the primary of which is continuously energized by generator G<1>. Normally the voltages in the windings 12, 14 are in opposition with the latter in excess. The resultant current maintains winding 25 energized and contacts 28, 34 closed. A brake valve magnet BV is normally energized from generator G<1> through contact 34. A relay J has two normally energized windings 30, 32, the circuit of the former including a relay contact 31. The effect of the two coils is additive, and energization of both is necessary to maintain the relay contacts closed. Coils 15, 16 are in series with windings 23, 24 on the relays J, R. Each time the core 17 passes over a track core 18, the increased magnetic flux increases the current in winding 12 and deenergizes winding 25. Relay contacts 28, 34 open or remain closed according to conditions described below. Under clear conditions contact 7 is open and 8 closed. The greater portion of the flux thus passes through coils 9, 15, and the current induced in coil 15 exceeds that in coil 16. The excess current passes through windings 23, 24 in the direction to keep the relay contacts 31, 36, 28. 34 closed. The signal light G and magnet BV are thus maintained energized. Under caution conditions, contact 7 is closed and 8 open. Excess current is induced in coil 16 and passes through windings 23, 24 in a direction opposite to that described above. Contacts of relav J are thus opened at 31, 36 and closed at 37. thus energizing lamp Y. At the same time the current in winding 24 maintains the contacts of relay R closed, so that magnet BV remains energized. Under danger conditions contacts 7. 8, are both open. Flux then passes equally through coils 15, 16 so that no current flows through windings 23, 24. Contacts of relay R are thus opened so that circuits of the lamps G, Y and magnet BV are broken at contact 34, circuit of a danger signal R<1> is closed at 38, and circuit of winding 25 is broken at 28, allowing the relay contacts to remain released when the vehicle leaves the track device. The track rails 1. Fig. 1 are in sections with insulating joints 2. Each section has a track relay M, M<1>, &c. and is supplied with current from a source 3 reversibly connected to the track by contacts 5, 6 of the track relay of the adjacent section. The relay contacts 5, 6 are, neutral and are held in normal position as at M when the relay is energized by current of either polarity. Each relay has polarized contacts 7, 8 moved to the right or left according to the polarity of the current supplied, and taking up the intermediate position when the relay is de-energized. As shown, the vehicle V in section DE de-energizes relay M<2> so that section CD receives current of reversed polarity and its track windings 9, 10 are opened at contacts 7, 8, thus signalling danger conditions, and stopping, a following train. Relay M<1> receives reversed current and its contacts 7, 8 are moved to the left. Coils 9, 10 of section BC are thus set to give a caution signal. Relay M receives current of normal direction and its contacts 7, 8 occupy the normal position to the right. Coils 9, 10 of section A, B are thus set to give a clear signal.