GB886253A - Improvements in or relating to electric snap action switches - Google Patents

Abstract

886,253. Press-button retractive switches. BROOKHIRST IGRANIC Ltd. July 2, 1958 [July 2, 1957], No. 21178/58. Class 38 (5). A snap-action switch comprises an actuator plate 50 guided in slots 18 in the base 10 and urged to the position shown in Fig. 1 by a compression spring 54. Fixed contacts 26, 30 are fixed by rivets 28, 32 holding terminals 34, 36 in recesses in the base 10. The movable contact assembly comprises a rigid carrier 38 having a central opening with guiding notches 40 for the plate 50, and knife edges 48 which engage similar notches in guides 64 for compression springs 62, the notches being wide enough to prevent relative lateral rotation. Similar knife edges 60 on the plate 50 engage other guides 64 so that the carrier 38 is floatably mounted. Leaf-spring contact members 42, secured by rivets 44 to the carrier 38, are stressed to bias their ends away from the carrier into engagement with lugs 46, notches in the carrier-ends allowing members 42 to abut flush against the carrier. In operation the spring force exerted by contact members 42 urges the carrier 38 in the opposite direction to the movement of the plate 50, to swing the springs 62 through dead-centre while still maintaining pressure on the fixed contacts. Arcuate movement of the members 42 produces a contact-wiping action. Various modifications of the contact assemblies are described for single-circuit operation and a modification of the movable contact assembly is described in which the lugs 46 are replaced by other means (Figs. 11, 12, 13, not shown).