GB857659A - Improvements in, or relating to, electric tumbler switches - Google Patents

Abstract

857,659. Tumbler switches. WANDSWORTH ELECTRICAL MANUFACTURING CO. Ltd. July 22, 1957 [July 20, 1956], No. 22476/56. Class 38 (5). In a switch, particularly for A.C. circuits, having the moving contacts 13 mounted on an insulating block 15 and moved relative to the fixed contacts 12 by a dolly 31 pivoted within a bridge 4 fixed to the switch base 1, the block 15 carries a spring-loaded stud 21 which is reciprocable in carrier 18, 19 depending from the bridge 4 and embracing and pivotally supporting the dolly so that the block, carrier and bridge can be assembled as a single unit prior to the fixing of the bridge upon the base. In the double-pole switch shown, the upstanding arms 19 of the carrier are attached to the bridge 4 by screws 34 which have non-threaded portions 35 to allow slight relative movement and so equalize the contact pressure. Each pair of moving contacts 13 is carried on a bar 14 which is secured to the block 15 by a rivet 17 also allowing slight movement. The stud 21 is cammed down to open the contacts by the arm 27 of a bell-crank lever 27, 28 which is pivoted at 29 to an inverted U-shaped bracket 30 secured to the dolly. The bracket 30 is pivoted about a pin 32 in the bridge 4 and the bifurcated arm 28 of the bell-crank lever embraces a pin 37 fixed to the carrier and coaxial with screws 34. A compression spring 39 surrounds the arm 28 of bell-crank lever between the pin 37 and the arm 27 to retain the switch in either of its set positions.