Patent GB-135461-A (GB)
IPC: B61L3/22
Filed: 1919-07-16
Abstract: 135,461. McKenzie, Holland, & Westinghouse Power Signal Co., (Assignees of Lewis, L. V.). Nov. 21, 1918, [Convention date]. Electrical systems, automatic; track apparatus actuating signals on trains and for stopping trains.-In systems of signalling on trains and actuating speedcontrolling apparatus on trains by means of currents induced in train-carried coils in proximity to the track rails by two alternating currents, one traversing the track rails of a section in parallel and the other traversing the rails in series as described in Specification 131,923, the source of current is connected to the middle points of non-inductive resistances connected across the track rails so as to cause the currents to traverse the two rails in parallel. The sections of track are subdivided by supplying current at an intermediate point to the rails in parallel. Fig. 1 shows the track circuits and Fig. 2 shows the apparatus on the train. The rail section BC is insulated by joints 2, and is supplied with energy from the transformer Tc through an inductive resistance 3 and current is supplied through the opposite rails in series to the coil 4 of the relay Hb. The phase of the current supplied is reversed by the contacts 15, 16 of relay Dc, which is energized when relay Hc is energized. The armature 14 of relay Dc controls the supply of energy from the transformer Ub to either the whole section BC through the wire 26 and non-inductive resistance- Mc or to the portion BE of the section through the wire 28 and the resistance Me, these circuits being completed through the rails in parallel and the non-inductive resistance Mb1 and the contact 8 of relay Hb, which is closed only when the relay is de-energized by a train occupying the section. Visible signals shown as lamps R, Y, G are controlled by the contacts 7 of the track relays and by the contact 17 of the relays Db, Dc. A train V<1> in advance of the point C de-energizes both relays Hc, Dc, and current of reversed phase is supplied to the rails BC in series through transformer Tc, and the current from transformer Ub is supplied to the rails in parallel in the section BE only. Relays Hb, Db supply normal current to the rails of the rear section in series and to the whole of the section in parallel. The train carries two iron yokes 34, 34a in proximity to the rails, these yokes being wound with two sets of coils. The coils 35, 35a are wound so that currents in opposite rails in opposite directions induce additive potentials, and these coils are connected to a condenser 38, an electron amplifier K1, transformer 53, and a second amplifier K2 to the coil 57 of a relay F. The coils 36, 36a on the cores 34, 34<a> are so wound that currents in opposite rails in the same direction induce additive potentials which by similar arrangements of amplifiers K3, K4 control the coil 63 of the relay F. By these arrangements, the phases of the currents in the two coils of the relay F are the same as those of the two inducing currents in the track rails, and the armatures 68, 69 of the relay F may control a relay L and lamps RYG to give visual indications. A speed-controlling device is also included in the circuits controlled by these relays. When the track is clear and normal current is supplied by the transformer Tb and a train V deenergizes relay Ha, the relay F closes the circuit to the relay Ja and relay L closes the current to relay Jb. If the transformer Tb supplies reversed current to the rails in series owing to the occupation of the advanced section, the relay F is reversed and relay Jb only remains energized. When the train reaches the point E, if the advance section is occupied the coil 63 of the relay F is de-energized, and both relays Ja and Jb are cut out of circuit. If the relay Ja is energized the circuit to the brake-valve magnet Q is closed through the long arc contact 89 and the arm 101. completes the circuit so long as a fixed maximum speed is not exceeded. If the relay Ja is dead and relay Jb is energized, the are 95 is in the circuit and an intermediate maximum speed is permitted. If both relays are cut out the circuit includes the short contact 98 and low speed only is possible.