GB591154A - Improvements in snap action electric switches - Google Patents

Abstract

591,154. Snap-action switches; retractive switches. DEHN, F. B. (Hetherington & Son, Inc., R.). March 28, 1945, No. 6771. [Class 38 (v)] In a snap-action switch a contact-bridging bar carries parallel springs which engage tapered surfaces on a plunger, so that movement of the plunger results in movement of the bridging bar to connect or disconnect a pair of fixed contacts. In Fig. 2, the bridging bar comprises a metallic plate 57 secured to a preferably insulating plate 58, between which plates a pair of springs 72, 73 is secured. As shown in Fig. 6, projections 64, 65 on the plate 58 register with notches 63 in the plate 57, the springs 72, 73 being retained between the plates by ears 67, 68. The Specification describes with drawings other forms of the bridging bar. When a spring- returned insulating button 32 is depressed, a plunger 39 having tapered surfaces 54, 55, moves through the bridging bar until the crest 56 passes the springs 72, 73, whereupon the bar snaps over and bridges contacts 48, 49. The surface 55 is of steeper slope than 54, so that the opening movement is more rapid than the closing movement. In Fig. 10, the casing 25 and the button 32<1> are both conducting and earthed, and the insulating sleeve 36<1> has a metallic end 37' whereby the contacts 48', 49<1> are earthed when the button is depressed. In Fig. 16 (not shown), the push-button return-spring is omitted and the casing is threaded for mounting purposes. In Fig. 21, the plunger 39 is secured to a spring- loaded cylindrical guide 92 which is moved within the casing 25 by a cam-lever 89. In Fig. 25 (not shown), depression of the button opens normally-closed contacts.