GB1225963A - - Google Patents

Abstract

1,225,963. Actuation of switches. MIDLAND ELECTRIC MFG. CO. Ltd. 14 March, 1968 [27 Feb., 1967], No. 9182/67. Heading H1N. A motor isolator switch has a slidable contact carrier 12 provided with limbs 12e mounting a rod 13, a first cam 14 being disposed between the limbs 12e and extending between a cross-bar 12a of the carrier and rod 13, and a second cam 16 extending on the other side of rod 13. A post (14b, Fig. 2) and a notch (14c) on cam 14 and a notch (16b, Fig. 2) and a post (16c) on cam 16, respectively interfit so the two cams rotate as a unit, diametrically opposed pairs of cam surfaces 14a and 16a forming a pair of helical cam slots coacting with rotatable anti-friction sleeves 15 on rod 13. Posts (14b, 16c) coact with fixed stops 17 to limit angular movement of the cams. Contact carrier 12 has three movable contacts 12c which co-operate with three pairs of fixed contacts in base 10, and plungers 12d which coact with plungers of two auxiliary switches in base 10, as in Specification 1,135,751. A spigot 18 on cam 16 has recesses 18a into which rollers 20 mounted on pivoted links 21 are urged to bias the cams to their limiting positions. A stem 19 on cam 16 coacts with a slot in the spindle 25 of an operator 22 mounted on a hinged or removable cover 23. A plate 26 on cover 23 has a slot 26a that can fit over the head of stem 19 when the cams are positioned such that contacts 12c are spaced from the fixed contacts. When the cams are rotated through 90 degrees and contacts 12c bridge the fixed contacts, and the head of stem 19 interferes with plate 26 and prevents removal of cover 23. A member 27 on spindle 25 and a leaf-spring 28 on plate 26 bias operator 22 to either of its stable positions.