GB815313A - Improvements in and relating to control systems for electric motors - Google Patents

Abstract

815,313. Controllers; control of D.C. motors; actuation of switches. KALYNYCZ, I., and COX, W. A. March 4, 1957 [Dec. 7, 1955], No. 35044/55. Classes 38 (3) and 38 (5). Relates to means which prevent the supply of current to a traction motor to drive the motor in one direction whilst it is rotating in the opposite direction. A two-way switch 1 is coupled to the reversing switch of the vehicle so that strip 6 engages contact 8 or 9 when the reverser is in the " forward " or " reverse " positions respectively. A double-pole switch 2 has contacts 10, 11, and 12, 13, which are respectively actuated to the closed positions in accordance with the forward or reverse rotation of the traction motor. Thus, when the vehicle is in motion, the motor circuit is opened if the switches 1 and 2 do not occupy corresponding positions. A shunt switch 24 is closed, when a hand brake is applied, to enable the motor to be started. When the brake is removed, the switch 24 is opened and the motor is placed under the control of the switches 1 and 2. A bolt 25 is adapted to engage disc 5 and hold it in the " neutral " position, the bolt being withdrawn against the action of a spring by means of solenoid 27 when the switch 24 is closed. As shown, the switch 2 comprises a disc 17 which is coupled to a motor-driven shaft 18 through a slip coupling. A bar 15 extends between the spring-contacts and is coupled by pin 16 to the member 17. In another arrangement, the double-pole switch comprises two pairs of contacts, each pair having a fixed and movable element. The movable elements are carried on spring-biased pivoted arms which are engageable by an intermediate member frictionally coupled to a motor-driven shaft, Figs. 7, 8 (not shown). In this manner, one or other of the contact-pairs are opened in accordance with the direction of rotation of the motor-shaft. Stops are provided to limit the movement of the pivoted arms, and the switch is carried in a casing which is angularly adjustable about the motor-driven shaft. This enables contacts, which may have remained open after the motor has been stopped, to be closed manually.