GB931991A - Improvements in snap-acting electric switches - Google Patents

Abstract

931,991. Retractive switches. NATIONAL ACME CO. Aug. 3, 1960 [Aug. 13, 1959], No. 26899/60. Class 38 (5). In a snap-action limit switch the operating machine member rotates lever 42 and hence coupled clutch members 17, 18 clockwise to bring an operating cam 20 into the position shown. The cam-follower 108 thus moves slider 101 to the left, detent 103 striking a shoulder 93 on a latched plate 90 to compress the snap spring 105. A release stud 109 on the slider 101 then reaches the position shown in Fig. 6, where it trips spring-loaded latches 118 to release lugs 93 and allow the spring 105 to snap the slider 101 to the left. This carries with it the contactcarrier 81 so that spring-loaded contacts 83, 84 leave a contact pair 66 and engage a similar pair 65 with a snap-action. Upon release of the operating lever 42, cam-spring 36 returns the cam 20 to normal and return spring 107 urges the slider 101 to the right. The contacts 83, 84 thus snap back under the control of bell-crank latches 119. In order that the switch may be operated instead by a counterclockwise movement of the lever 42 and cam 20, the cam member 17 may be withdrawn manually from its drive member 18 and rotated through 90 degrees. The contacts are separated from the operating mechanism by a slotted partition 14 and the switch is closed by cover-plates 12, 13 and gaskets (not shown). The contacts may be replaced by butting contacts 140, 142 (Fig. 9) and in this case additional shoulders on the latches 118 may provide a central OFF position. Specification 912,223 is referred to.