GB565450A - Improvements in and relating to electric snap-action switches - Google Patents

Abstract

565,450. Snap - action switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 31, 1943, No. 21903. Convention date, Jan. 2, 1943. [Class 38 (v)] In a snap-action switch in which the contactoperating member is held in either position by a latch adapted to be tripped near the end of the switching movement, each latch has an additional stop means for preventing movement of the member beyond its normal position. In a two-way limit switch, in which a movable contact 20, Fig. 5, bridges a pair of contacts, as 18, in each end position, the contact and its operating yoke 22 and spacing springs 23 are slidable on a rod 21 by means of a rocker shaft 27 and lever 28 coupled to the yoke 22 by a pin 24 and slot 25. A spring-pressed ball 39 in a lever 40 is slidable along the under-surface of lever 28 with a dead-centre action, the lever 40 being pivoted freely on a shaft 42 carrying a gear-wheel 46 in the bifurcated shaft-end 41. The gear 46 meshes with a rack 47 slidable in the bifurcation, and the ends of a C-spring 48 are located in slots in member 47 and bear on the sides of lever 40. During clockwise rotation of shaft 42, Fig. 3, spring 48 transmits the force from the rack 47 to move lever 40 over-centre. When the lever engages the pivoted latch 30, the shoulder 37 thereon frees lever 28 which rotates anti-clockwise until arrested by the stop 38 on latch 30, at which point the latching shoulder 37 of latch 29 is just forced by its spring 33 over the other end of lever 28. The latch-movements are limited by the abutments 35 in which the springs 33 are seated. Operation into the other position is similar and may be assisted by a spring 43 acting on lever 40. Cases.-The contact-chamber 14 is,separated from the operating-mechanism by a partition 11 and has a cover 12, a gas-vent 16 exhausting through a further cover 13.