Patent GB-190307618-A (GB)
Title: Improvements in and relating to Switches for Starting and Regulating Electric Motors
Inventor: MOULD JOHN THOMAS
Filed: 1903-04-01
Granted: 1904-03-31
Abstract: 7618. Mould, J. T. April 1. Motors, controlling. - In starting-switches for motors, the rheostat arm is so controlled that, while a quick movement takes place from one contact to the next, a pause is made between each such movement ; or, instead of a rheostat arm moving over contacts, a series of switches may be separately actuated to cut out resistance. The operating-mechanism is reciprocated, and may be electromagnetic or other. In the construction shown in Fig. 1, the rheostat arm A is fixed to a disc B provided with ratchet teeth. The disc is moved by a pawl G carried by an arm F pivoted at C and connected by a link H to a core b of a solenoid a. The coil carries a bridging- piece c engaging contacts adapted to close the circuit of an electromagnet h and also of the solenoid a. In operation, the circuit of the coil s is first closed ; this closes the main switch Q, and also the circuit of the electromagnet h, which closes by its armature the circuit of the solenoid a; the core b is then drawn in, and the arm A moved. A shield &c. J is placed over the ratchet disc B to limit the engagement of the pawl. When the cover h is fully raised, the bridge c leaves the contacts, and the circuit of the coil a is broken ; the core h then descends under the influence of gravity or a spring, at a speed dependent upon a retarding-device or dash-pot V, and again makes contact at the bottom of its stroke. In modified arrrangements, the core may be returned by a second solenoid, the circuit of which is closed when that of a is opened. When the arm A has cut out all or any desired part of the resistance, it opens a switch N, and so cuts out the coils h, a. When the main switch Q is opened, the retaining-pawl R is raised, and the disc and arm A are rotated by a spring &c. to reintroduce the resistances. A high resistance W is introduced into the circuit of the coil S, so that the main switch cannot be closed unless all the resistances are in the motor circuit and the arm A short-circuits the resistance W. In a modified arrangement, Fig. 2, instead of using the coil h for breaking the circuit of the coil a, a switch t connected by a spring u to the core may be employed. In a modification, Figs. 3 and 4, a number of switches 3 are successively actuated. The core b is connected by a link H by a bail or bar 2. The switches 3 are pivoted on a shaft 4, and between them are intermediate levers 5 having projections 6, 7, one on each side, which engage with the switch arms 3. The first switch arm 3 has a rigid projection 8. On raising the bail, the first switch 3 is closed, the bail striking against the projection 8. The first switch in closing engages the projection 6 on the first lever 5, and moves the lever so that, at the next upward movement the bail engages the first lever 5, the projection 7 of which engages and closes the next switch, and so on. The last switch arm opens the switch N, M controlling the circuit of the solenoid a. The switches are held closed by hooks 10, Fig. 4, engaging hooks 11. The hooks 11 may be mounted on a rocking shaft 12 controlled by the main switch, so that, when it is opened, all the switches 3 are released. The switch T for starting or stopping the motor may be operated by a float, or by means controlled by the motor, which may then be self-starting.