GB688267A - Improvements in or relating to electric switches having a dolly or like pivoted operating member - Google Patents

Abstract

688,267. Tumbler switches. ASHLEY ACCESSORIES, Ltd., and EVERITT, L. H. R. Jan. 10, 1951 [Jan. 19, 1950], No. 584/50. Class 38 (v) In a switch having a dolly or like pivoted operating member, the closing force is applied to the movable contact through a permanently-compressed spring which is not further compressed until the contacts engage, whereby the contact pressure is increased. In Fig. 1, a movable bridging contact C is supported by springs D which normally hold the contacts open. The dolly E bears on the cross-piece of an inverted- U-member F, the lower ends of the arms of which are inturned under the contact C, with a spring G compressed between the cross-piece of the member F and the upper face of the contact, the spring G being stronger than springs D. Counterclockwise movement of the dolly causes the member F, spring G and contact C to move together initially until the latter engages the fixed contacts A, B, further movement of the dolly further compressing the spring G. In Fig. 5, the dolly 14 has a pin 29 engaging a slot 30 in a rocker arm 31, a spring 33 being compressed between the pin 29 and the head 32 of the arm, which bears in a depression 21a in the movable contact 21. Movement of the dolly, moves the rocker arm over dead-centre to open or close the contacts. In Fig. 6, the contact 21 has brackets 35 with slots 36 receiving a pin 37 carrying a roller 38 which co-operates with two recesses 41, 42 of different depth formed on either side of an intermediate nose on the dolly. The dolly is preferably pivoted to the switch cover (not shown), the remaining parts being mounted on the base. Specification 667,462 is referred to.