GB594847A - Improvements in electric switches adapted to be tripped open - Google Patents

Abstract

594,847. Automatic circuit breakers; switches held set and freed mechanically. CALLENDER'S CABLE & CONSTRUCTION CO., Ltd., RICHARDSON, A. B. F. G., and HALL, H. C. July 2, 1945, No. 16798. [Class 38(v)] A switch of the type which is held closed, against spring action, by a locking device such as a toggle, and is opened by a pushbutton or automatically by an electrothermal or - electromagnetic device comprises an insulating bar 10, of rectangular cross-section; slidable in a slot in.the switchbase 2, and carrying in recesses on both sides of the bar moving contact plates 5, with end portions 7 inclined at an angle of about 45 degrees to the direction of motion, outwardly urged against stops 54 on .the base, by blade springs 11, to bridge'the similarly-inclined switch contacts 17, so that they make and break with a transverse wiping movement. The fixed contact surfaces may be silvered, and the moving contacts may carry silver-solder projections 8. The toggle arms 27, 28 are pivoted respectively on the bar 10 and a bracket 32 on the base, and urged by a spring 35 so that the hinge rests on the bar just over the dead-centre. Also pivoted on the bracket 32 is a forked bell-crank lever having an upper arm 40 which, when engaged by a stop 43 on a pin 41 actuated by a tripping solenoid 44 or pushbutton 42 mounted on the cover, lifts the lower arm 38 passing under the toggle hinge-pin, and the main spring 23 housed in a recess under the bar 10, opens the switch. The speed of opening may be adjusted by frictional surfaces on the cover engaging the bar. In an alternative arrangement, Fig. 3, the switch is tripped by a press-button 50, and closed by a dolly 51 pivoted in the cover which is formed so as to mask the dolly when in the closed position.