Patent GB-190226038-A (GB)
Title: Improvements in and relating to Electric Track Brakes.
Inventor: CAROLAN EDGAR ALFRED
Filed: 1902-11-26
Granted: 1903-10-15
Abstract: 26,038. Carolan, E. A., [General Electric Co.]. Nov. 26. Electric motor vehicles.-Relates to electromagnetic track brakes for electric railway and tramway vehicles. Each brake shoe H is suspended by springs S, S' from a frame M which is hung on pins P, P' from brackets B, B<1> fixed to the frame A of the car so that the brake can adjust itself to the track. The drag of the brake is transmitted to the frame M and to the car through slotted links C, C<1> which are arranged so that the line of action passes approximately through the centre of the brake surface. The brake is energized by a coil N enclosed in the brake shoe, and held in place by a non-magnetic ring r and by the bolted-on brake surface k. When the brake is not in use, it is lifted by the springs S, S' and also by an electromagnet E consisting of a coil D, Fig. 2, enclosed in a magnetic casing by a non-magnetic plate F. The electromagnet E is suspended from the frame M, Fig. 1, by a bolt Q. Adapted to be attracted by the electromagnet E is a plunger I, Fig. 2, fixed to a plate J in contact with a magnetic plate P fixed to the brake shoe H, Fig. 1. The plate P is free to move horizontally with respect to the plate J but always maintains magnetic connection with it, thus permitting freedom of movement of the brake shoe, and at the same time maintaining the effectiveness of the lifting-magnet. The lifting-coil D and the brake-energizing coil N are connected with the motor system and the motor controller in such a manner that the lifting-magnet is always energized whenever power is being supplied to the motors, and that the brake magnet is energized by the motors working as generators. The connections are made as shown in Fig. 4, K representing the controller, X the reversing-switch, L, L' the armatures of two motors, 0, O<1> their fields, E, E' the brake-lifting magnets, N, N' the brake-applying magnets, G ground connections, T the trolley connection, and R' the motor regulating resistance. When the controller is moved one step in a direction to supply power to the motors, the current passes from the trolley T to the ground through two parallel circuits, one consisting of part of the resistance R', the motor L and its field 0, the brake-lifting magnets E, E', and the other motor L' and its field 0<1>, and the other consisting of the remainder of the resistance R
, a resistance DR, and the brake - applying magnets N, N', all as shown in Fig. 5, the second circuit being for the purpose of demagnetizing the brake and allowing it to be lifted more easily. The next step in the movement of the controller cuts out the brake magnets N, N<1> and at the same time lessens the amount of the resistance R<8> in the motor circuit. In two more steps, the amount of the resistance R
 in the motor circuit is reduced to nil. Succeeding steps increase the resistance again, disconnect the motor L', connect it up again in parallel with the motor L, and finally reduce the amount of the resistance R
 in circuit to nil, the motors then running at full power. The motor L and the magnets E, E<1> remain in circuit during the whole movement. To apply the brake, the controller is brought back to the "off" position shown in Fig. 4, and its movement continued to bring the contacts shown to the left of Fig. 4 into operation. The first step completes a circuit from the ground through the brake magnets N, N', through part of the resistance R
, and through the two motors L, L' in parallel, as shown in Fig. 17, the brake - lifting magnets E, E<1> being left in circuit as they are not sufficiently powerful to resist the action of the magnets N, N'. A connection Z equalizes the action of the two motors, now working as generators, and the relation of the armatures and fields is reversed. Successive steps in the movement of the controller reduce the amount of the resistance R
 in circuit to nil, and cause the brakes to be fully applied.