ES319259A1 - Three position limit switch - Google Patents

Abstract

A limit switch assembly 4 operable by a relatively movable part 1, e.g. a machine tool part, has a movable contact-carrying member 13, which is movable by an actuator 11 between three positions, leaf springs 14, 15, interconnecting member 13 and actuator 11 providing for snap-action movement of member 13, and centring means such as a spring 9 tending to hold member 13 in its intermediate position. The camming surface of the relatively movable part 1 may co-operate with a spring (19), (Fig. 2, not shown), to restrain the member 13 in its intermediate position until sloping surfaces (20A) or (20B) are reached. Member 13 connects contacts A 1 ,B 1 ,or A 2 , B 2 ,in its end positions and connects contacts A 1 , B 2 , in its intermediate position. Alternatively member 13 is insulating and carries self-aligning bridging contact members (32A), (32B), (Fig. 6, not shown). Part 1 actuates actuator plunger 11 via a pivoted lever 6 which may rotate a cam 21, (see also Figs. 3, 4a, 4b, not shown), which acts via a ball 23 and rod 25 on plunger 11, a sealing disc surrounding rod 25. The switch assembly 4 controls a continuously reversible motor (Fig. 10, not shown), a reversible motor (Fig. 8, not shown) or two separate motors for driving a machine tool part 1 forwards and backwards. Apart from the centring means, the switch is similar to that of French Specification 1,328,440.