GB577126A - Improvements in or relating to snap-action electric switches - Google Patents

Abstract

577,126. Snap-action switches. BRITISH MECHANICAL PRODUCTIONS, Ltd., and FUKE, F. C. May 30, 1944, No. 10416. [Class 38 (v)] A switch is arranged to close a circuit by rocking a contact arm through a dead centre to bridge two fixed contacts forming a bearing in which the contact arm may float. The pushrod 22 of D-section is in two parts joined by a screw 32 engaging a slot 36 in the base 20, so limiting the travel of member 22. The rocking contact arms 35 are pivoted to springs 37, pivoted on pins 33 in the member 22 to provide the snap-action, and the outer ends of the arms 35 have a floating bearing formed by a channel between the fixed contacts 23, 24 which they bridge in the " closed " position, the arms resting on contacts 24 in the " open " position. A dome covers the live parts and is secured between arcuate flanges 21 by screws 30. The outer ends of the rocking arms may be of ball, roller or other arcuate shape or have separate rollers, Figs. 7, 9 (not shown). The snap-action may, alternatively, be provided by U-shaped springs or by a single helical spring insulated from the rocking arms, Figs. 7, 5 (not shown). In place of the double-pole, one-way arrangement described, single-pole one-way or two-way switching may be provided, respectively, by idle bearing of one rocking arm or by cross-connection of diagonallyopposed contacts 24. An intermediate switch may be provided by so introducing auxiliary fixed contacts that in one position the rocking arm rests on the two main fixed contacts, while in the other position it rests on an auxiliary contact and one main contact. In a tumbler switch, Fig. 8, the rocking-arm 35 carrying a contact roller and a dead-centre spring 45 is operated by a dolly 44. Specification 552,181 is referred to.