GB1244869A - Electrical switch - Google Patents

Abstract

1,244,869. Mechanical switches; actuation. CROUZET. 20 Dec., 1968 [26 Dec., 1967], No. 60824/68. Heading H1N. In a limit switch having a control head 1, Fig. 1, which is adjustable to alternative positions by rotation about the axis of an actuating push-rod 5, the fixed switch contacts, 18, 19 are mounted within an insulating case 16, 17 and are engaged alternatively by bridging controls 32 pivoted on opposite sides of a slide 14 actuated from the control head via a push rod 5 and an L-shaped lever 6. The contact assembly case 16, 17 is mounted on the metal cover plate 20 by screws 53 and has a recess 17d containing a pivot pin 12 for the L-shaped lever 6. Carriers 30, Fig. 4, for bridging contacts 32 are pivotally mounted on each side face of the spring-loaded slide 14 and are retained in position by snapaction tension springs 31. Each bridging contact 32 is loosely mounted in a slotted plate 33 extending from each carrier 30 whereby the contact 32 is self-aligning with the movement limited by stops 30d. The external cables (not shown) extend through the metal casing 21 at threaded aperture 21c containing a cable stuffing box (not shown) and enter recesses 27a, Fig. 12, under terminal screws 29. A terminal strip 28 is held in position by lugs 28b, 26g in recesses of the insulating box 26a of the terminal box 25 and having bent-up lugs 28a engaged by the terminal lugs of the switch contacts which are inserted at F when the switch cover 20 is attached. In the example illustrated the control head 1 contains an operating plunger 3 having a cam face engaging a ball 4 mounted above the slidable push rod 5. Projections 1b on the head engage alternative recesses 20d in the switch casing and the assembly is held by screws 2 (not shown) engaged in threaded bores below the recesses 20d. In a modification the control head, Fig. 5 (not shown), contains a rotary spindle operator (36) having an operating arm (35) keyed at the exposed end. The spindle carries a cam (40) engaging the ball 4 above the push rod 5. Alternative detent cams may be mounted on the end of the spindle for engagement by spring-loaded rollers. Different shapes of cams are described whereby the operator may be retractive or retained set in each of its operated positions.