GB648682A - Electric snap switch - Google Patents

Abstract

648,682. Press-button retractive switches; snap-action switches. IGRANIC ELECTRIC CO., Ltd. June 23, 1947, No. 16519. Convention date, Oct. 20, 1942. [Class 38(v)] A retractive dead-centre snap-action limit switch comprises a lever 28, Fig. 3, pivoted to an upstanding lug 24c, of a fixed bracket 24 and to a contactcarrier 29b having a lug 29a co-operating with an opening 28e in the lever 28. Two coil springs 30, on either side of lever 28, are fixed at one end to the bracket 24 and at the other end to. extensions 29d of the carrier 29b, so that when plunger 23 is urged downwards upon engagement thereof by a lever or cam, the lever 28 moves across the centre-line of the springs and the contact 30b moves into engagement with the upper fixed contact 31a. A return spring 35 is factory adjusted to the position shown by a screw 36, the shank of which is then bent and secured in a recess 20n by wax or cement 37. The fixed contacts are preferably stamped from layered sheets of brass and silver. In modifications, Figs. 7-10 (not shown), the upper or lower fixed contacts may be replaced by stops and the contact-gap may be enlarged by bending the stops twice through 90 degrees. In Fig. 11 (not shown), the coil springs 30 are replaced by a single coiled spring, the pivoted lever 28 being bifurcated to receive the spring. In order that the switch may be manually actuated, a member 53, Fig. 14, carrying a pushbutton 52 is attached to the switch cover. The push-button comprises telescoping portions 52a, 52e, and its downward movement is limited by the engagement of the bottom of portion 52e, with the cover 21, and its upward movement is limited by a flange 52i engaging with a flange 59a of a fixed bush 59. The push-button may alternatively comprise a plunger, Fig. 15 (not shown), sliding in a fixed sleeve.