GB190925205A - Electric Motor and Controlling Systems. - Google Patents

Abstract

25,205. Barker, G., [Welch, H. C., and Parkman, H. K.]. Nov. 2. Motors, controlling.-Multipolar series electric motors for use in the operation of elevators, machine tools, vehicles, &c. have their field windings composed of a number of groups of coils F<1> ... F<4>, Fig. 1, each group being composed of a different number of turns, and are controlled by successively cutting-out the coils of each group by means of a manually-operated switch mechanism, which is automatically locked by an electro-magnet when the current exceeds a predetermined. value. Each pole of the motor is provided with four windings, the coils F<1> being of relatively fine wire and many turns, the coils F<2> of coarser wire and fewer turns, the coils F<3> of still coarser wire and fewer turns, and the coils F<4> proportioned for the maximum speed under full-load conditions. The motor is excited from a battery through stationary contacts 4 ... 8 and movable contacts 9, 10, 11 on a drum mounted on a shaft 40, Fig. 3, actuated by means of a rack and pinion 50, 49. A contact 16 connected with the shaft 40 by a spring 17 rotates with the contacts 9, 10, 11 and engages with fixed contacts 20-32, the groups of coils F<1> ... F<4> being successively cut out. The individual coils of each group are also cut out successively. The drum 46 carrying the contact 16 gears with a pinion 54 loosely mounted on a short shaft 55. The pinion 54 is provided with clutch teeth 59 adapted to engage with a sliding sleeve 60 splined on the shaft 55. Should the current at any moment exceed a predetermined value, an armature 57 will be attracted. by the electro-magnet 33 and so prevent the rotation of the drum 46. This automatic device may be thrown out of action when desired by closing the circuit of an electromagnet 63 to release the clutch 59. Reversal is secured by means of the contacts 12 ... 15.