Patent GB-190400818-A (GB)
Title: Improvements in Electric Railway Systems.
Filed: 1904-01-12
Granted: 1905-01-12
Abstract: 818. British Thomson - Houston Co., Sporborg, H. N., Carter, F. W., and Cubitt, A. S. Jan. 12. Heating.-In multiple-unit electric trains, the continuity of the current supply to the lighting, heating, and control circuits is maintained, despite the passage of individual collectors over gaps in the conductor, by the use of train-wires of small capacity in conjunction with automatic switches which not only keep the train-wires constantly supplied but also guard against the passage of heavy motor currents through these wires. In the form of the invention shown in Fig. 1, the lighting, heating, and control circuits x are connected across wires a, b running throughout the train. On each motor car is a relay switch d, the solenoid e of which is connected in series between the positive collector and the negative collector k, so that, normally, the switch arms g, h are in the position shown, where they connect the wires a, b of the car to the collectors j, k respectively. On the collectors reaching a gap in the conductor, the solenoid e is de-energized, and the arms g, h drop to a position where they connect the wires a, b of the car with the wires of an adjacent car, and at the same time disconnect them from the collectors. To ensure the possibility of connecting always the wires a, b of any car to those of a live car, the wires are connected at the ends of the train to a second pair of train-wires p, q, couplings being provided to allow of this connection in any relative arrangement of the individual cars. Two modifications are described in which only two train-wires are used. In one, shown in Fig. 3, each motor car has a pair of polarized relay switches d<1>, d<2>, each having two movable members g<1>, v or h<1>, wand polarizing-coils 5, 6 in series with the main control circuit (not shown). Normally, the coils 5, 6 are energized and thus hold the switches in the position shown, where the lighting &c. circuits x are completed from the positive collector j<1> to the negative collector k<1> through the switch arms g<1>, h<1>, and the train-wires a<1>, b<1> are in connection with the positive and negative collectors through the switch members and solenoid and coils v, e<1> and w, e<1> respectively. When, however, the collectors of the car come to a gap, the coils 5, 6 are no longer energized, the switches d<1>, d<2> therefore rise, and the lighting &c. circuits are completed between the wires a', b<1>, which are now fed from an adjacent car instead of between the collectors. The passage of a heavy current between the wires a<1>, b<1> by way of the collectors and motors is however prevented by the resistances v, which, owing to the rising of the switch members v, w, are now no longer shortcircuited. In the other modification, in which two train-wires only are employed, each motor car has two differentially-wound relay switches, which are arranged normally to retain automatic switches in the motor circuit of the car in their closed position. On the collectors reaching a gap, one coil only of each relay remains energized, namely, that through which the lighting &c. circuit is maintained from the train-wires, and the relay switches therefore open and cause the automatic opening of the motor circuit on the car.