GB783014A - Improvements relating to electric snap switch mechanism - Google Patents

Abstract

783,014. Snap-action switches. RANCO, Inc. June 9, 1955 [June 21,1954], No. 16585/55. Class 38 (5). A switch comprises a contact arm one end of which is movable between spaced stops, a toggle link pivoted at one end to the arm and at the other end to resilient means, the link also being pivoted between its ends by a pair of spaced fixed pivots. A spring contact arm 25 is mounted at one end by screws 26 on a bracket 13 and carries a contact 27 movable between contacts 28, 29. The toggle link 51 is rigid and has notched ends 52, 53 engaging the arm 25 and the resilient means (a C-spring 50) respectively. The other end of the spring 50 engages a part 55 of an actuator 42 which is mounted at its upper end, Fig. 2, and may be operated by thernally responsive means (not shown). The bracket 13 is connected to a terminal 15 and contacts 28, 29 to terminals 33, 37 respectively. The link 51 passes freely through an aperture in a fixed lug 22, the opposite edges 56, 57 of the aperture providing alternative pivots for the link. With the parts in the Fig. 6 position, the link 51 is biased counterclockwise about pivot 57 by the spring 50 so as to increase the pressure between contacts 27, 29. The link 51 is also biased axially thereof by the spring 50 to increase the contact pressure. Downward movement of the actuator causes the spring 50 to pass through a deadcentre position and the link 51 then moves from pivot 57 to pivot 56 about which it pivots clockwise to move the arm 25 with a snap action. The contact pressure is maintained until the dead-centre position is passed by the axial bias on the link 51. Reverse movement of the actuator causes similar return movement of the contact.