Patent GB-190425129-A (GB)
Title: Improvements in Electric Braking Apparatus.
Inventor: THOMPSON WILLIAM PHILLIPS
Filed: 1904-11-18
Granted: 1904-12-22
Abstract: 25,129. Thompson, W. P., [Stamm, L., and Lewis, E. D.]. Nov. 18. Electric locomotives and motor vehicles.-In an electric brake for railway and tramway cars, especially those driven by electromotors, and which allows the brakes to be applied by hand in the usual way, the shaft 1, Fig. 1, which works the brake chain 3 and brake lever 3<a>, is driven from a separate motor 6 which is operated from a hand-switch by the driver. The chain 3, Fig. 2, is connected to a cam 1<a>, which is provided on the shaft 1 to take up any slack in the chain quickly. A ratchet-wheel 4 is keyed to the shaft 1 and worked by pawls 4<a>, pressed by springs 4<b>, and connected to a worm-wheel 5, which runs loosely on the shaft 1 and is driven by a worm 5<a>. The ratchet mechanism is provided so that, if the motor runs reversed too long, the chain 3 will not rewind on the shaft 1. The two halves 5<e>, 6<e> of the coupling which connects the worm shaft 5<b> to the motor shaft 6<b> are insulated by a block 7 of fibre, into which enter pins 5<f>, 6<f> alternately from either side, as shown in Fig. 4. The controller for operating the brake motor may form a part of the main controller for the power motors of the car, or may be separate, as shown in Fig. 5, in which a switch A is operated from a handle A' provided with a pointer and index as shown, and a switch M, M' is held normally in the position shown, but may be attracted by an electromagnet 0. When the switch A is in the position marked 0, no current passes to the brake motors ; when it is in the position ¢, contact is made between pieces B', C, current enters from the trolley through a resistance b, and the brakes are applied slowly. The current passes from the contact C by a wire c to a contact-point C<5> of the switch M, from which it passes by a wire c' to one terminal 6<g> of the brake motor. From the other terminal 6<h> it flows to a contact-piece C<7>, to another contact N by the arm M', to fields 6 <i>, 6<j> by a wire n, through a resistance n' and wire n<2> to a contactpoint p, and thence to the earth by a wire n<3>. When the switch A is put in the position marked 1, contact is made between pieces C, B, and the current passes as before, except for the resistance b, the cutting out of which causes the brakes to be applied rapidly. To release the brakes, the switch A is brought into position 3, and contact made between O<1> and B<2>, by which means the current through the motor is reversed, entering at the terminal 6<h> after passing through the magnet 0 by wires o, o<2>. The magnet then attracts the switch M<1> on to the contact C<6>, so that the current coming out at the terminal 6<g> passes from the contact C<6> to the piece N, and then to the earth as before. A part of the current may pass directly from the magnet to the piece N by a wire N'. In the event of the main current from the trolley failing, the switch A is put round tc position 2, making contact with C and points P<2>, P<3>. The power motors P, P' of the car will then act as dynamos and send currents to the pieces P<2>, P<3> and thence to C, which supplies the brake motor as before. The current then passes through the fields back to the contactpoints p, p<1> and to the motors P, P<1>. By this system the brake motors of a number of cars can be controlled from the master-switch A, by providing each car with switches M, M' and their related contacts, and connecting the magnet 0 and contacts C<5> of such switches in multiple with the points C, O<1> of the master-controller A.