GB559997A - An improved lock switch for lift gates and the like - Google Patents

Abstract

559,997. Locking lift gates etc.; mechanical switches without quick action. FURSE & CO., Ltd., W. J., and BROWN, F. Sept. 2, 1942, No. 12358. [Class 78 (iii)] [Also in Group XXXVII] Relates to a lock switch for use where an electrical circuit is controlled by closing or opening a door or the like, particularly a lift gate or door, and of the type incorporating electrical contacts 15 adapted to be operated by the entry and withdrawal of a pawl or tongue 12, the lock switch and pawl being mounted respectively on the two relatively movable parts to be locked together, e.g. a lift gate and the jamb. According to the invention, the pawl 12, or an associated part, is adapted, on entering the lock switch, to engage an inclined track 18 on a rotary switching member 16 and thus rotate the member to connect the contacts, so that, in the case of a lift, the lift motor can only be started when the gates are shut. As shown, the lock switch comprises a casing 10 attached to the jamb and having a slot 11 for entry of the pawl 12, carried by a lift gate or door, while the member 16 is a metal drum carrying an insulated metal bridging bar 17 which closes the contacts 15 when the Z-shaped track 18 on the drum is engaged by a projection 14b on the pawl, to rotate the drum against the action of a spring 19. On rotation of the drum, the opening 11 is obstructed by a guard plate 21 engaging behind the vertical part 14 of the pawl, the guard plate being moved by a peg 22 on the drum engaging a hole 23 in the plate which is pivoted at 24 to the casing 10 and determines the inoperative position of the drum. The lock also incorporates the usual locking lever 26 mounted on a spindle 27 provided with a lever 28 which is rocked by a ramp as the lift moves, the lever 26 being spring-biassed to hook over the horizontal part 13 of the pawl. In addition, to prevent the pawl from being operated without the exertion of some effort when the lever 28 is disengaged, a spring-loaded plunger 30 or the like is provided which is raised by an inclined part 14a on the pawl when the latter enters the casing 10 and drops into a recess 14c on the part 14.