GB451005A - Improvements in and relating to snap action mechanism for operating electric switches, valves and other devices - Google Patents

Abstract

451,005. Linkwork. RICHMOND, T. G., 77, Newlands Road, and MACLAREN & CO., Ltd., R., 110, Kilbirnie Street, both in Glasgow. July 26, 1935, Nos. 21259, 21704, and 21936. [Class 80 (iii)] [See also Groups XXXVII and XXIX] A snap-action mechanism shown applied to a thermal switch comprises a spring strut 18 mounted in compression between an adjustable fixed bearing 15 and a bearing 17 on an arm 5 which is pivoted at 6 and carries at its other end a contact 7 cooperating with a fixed contact 8. The bearing 17 is offset upwards relative to the line 6, 15 so that the arm 5 is biassed in a clockwise direction. A spring member 20 is fixed to the base of the switch and has an extension 21 which engages the strut 18. A member 29 bears on the spring 21 to push the strut 18 downwards, and as the strut approaches the dead-centre position its clockwise turning moment diminishes rapidly and allows spring 21 to move the contact arm rapidly downwards until arrested by a stop 12 which prevents the arm from passing the dead centre position and hence allows an automatic return on removal of the operating force. Specifications 288,595, [Class 80 (iv)], and 370,920, [Group XXXVII], are referred to.