GB280294A - Improvements in and relating to electric switches - Google Patents

Abstract

280,294. British Thomson-Houston Co., Ltd., and SaIisbury, A. G. Aug. 13, 1926. Push - button switches, particularly for the starting motor of automobiles, comprise a push-button which through a spring operates a bridging contact member which after it engages the fixed contacts is caused to rotate by further pressure on the button and thereby caused to rub upon the fixed contacts and maintain the surfaces clean. In the arrangement shown in Fig. 1, the non-rotatable button 6 has secured upon it a plunger 1 guided at its lower end in an aperture 12 in the casing and formed with a helical slot 14 with which projections upon the surrounding movable contact disc 2 engage. Springs 15, 10 are interposed between the button and the contact disc and between the disc and the bottom of the casing. When the button is pressed the disc and the spring 15 move downwards together until contact is made with the fixed contacts 3, if pressure is maintained on the button, the disc is caused to rotate upon the fixed contacts. If pressure is removed, the disc returns to the off position. In a modification, the helical groove is formed in the button and co-operates with projections on the casing while the contact disc is capable of longitudinal movement only in relation to the plunger.