GB701909A - Improvements in or relating to spring plunger electric contacts - Google Patents

Abstract

701,909. Contact members for switches; switch cases. COOPER, H. C., and MEK-ELEK ENGINEERING, Ltd. Oct. 2, 1951 [Oct. 16, 1950], No. 25202/50. Class 38(5) A contact comprises a plunger 13 urged by a spring 23 in a socket 7 and having a terminal projection 21 extending through a socket slot 20 which is closed at its upper end. As shown, a pair of sockets 7 of rectangular section are formed in an insulating block 14, the width of the sockets in the dimension shown in Fig. 4 increasing towards the base, to permit self-alignment of the plungers 13. The block 14 rests on an insulating angle-section member 16 and is secured by a screw 19 to the bottom 18 of a box housing a transformer 12, the transformer being carried by the box lid 8 and having contacts 10 which engage the plungers 13. Such a box is disclosed in Specification 664,073. The contact faces of the plungers 13 may be curved about an axis, or axes, extending across the two plungers to provide a line contact, Fig. 1, which may be shortened by slotting the centres of the faces. In another construction, Fig. 6 (not shown), both slots 20 are formed in the same longitudinal edge of the block 14. To prevent tilting of the plunger 13 by the spring 23 when the projection 21 reaches its outer limit of travel, a further projection 28 may be provided on the plunger 13, Fig. 7, and engage the closed end of a further slot in the block 14. Alternatively, Fig. 9, the upper part 29 of the plunger 13 may be hexagonal and the lower part 30 of different shape to form a pair of projections 31 which co-operate with similar-shaped shoulders formed in the socket bore, Fig. 11 (not shown). In another modification, Fig. 12 (not shown), the terminal projection 21 is permanently connected to a pig-tail. According to another construction (not shown) separate metal sockets for each plunger 13 may replace the block 14.