GB568630A - An improved latch for performing both a locking operation and an electrical switching operation - Google Patents

Abstract

568,630. Lift - gate fastenings. YOUNG, L. W. July 22, 1943, No. 11945. [Class 44] [Also in Group XXX] A fastening particularly adapted for gates of lifts and controlling electrical contacts in the liftoperating circuit comprises a pivoted hook-like catch 20 rocked into engagement with a fixed bolt 24 by the bolt entering a recess in the side of the casing 10 as the gate is closed, the catch carrying a contact which bridges a pair of fixed contacts when the catch is in engaged position, in which position it is held by a spring plunger 28, 30, the inclined nose of the plunger engaging the correspondingly inclined lower edge of the catch to give a wedging action. The catch and recess are arcuately shaped so that they thus fit snugly round the bolt and hold it firmly. Release is effected by withdrawal of the plunger by keyoperated or manual means. As shown, a lever 34 with handle 8 bears against the end of the plunger, retraction of which allows the bolt to rock the catch to release position when the gate is pulled towards open position. Either a part of plunger 28, or, as shown, a separate catch plunger 40, holds the catch in each of its extreme positons by engagement with suitably placed recesses such as 42, 44 formed in the catch. Plunger 28 is held retracted till the gate is closed by engagement with the righthand end of the catch after the latter has been rocked clockwise to release position. In a modification, lever 34 is extended so that its upper end, which is preferably eccentrically formed to give a cam wedging action, engages the lower edge of the catch to hold it in engagement, the plunger 28 in this form merely serving to bias the lever by engagement with the side thereof. The casing 10 is secured to the gate by bolts, not shown, passed through apertures 14 in the casing, the heads of the bolts resting within the casing and being hidden by a closure plate, not shown, secured by screws entering tapped holes 12. As shown, an insulated contact plate 48 on the catch bridges contacts 50, which may be spring plungers, respectively secured to the wires 54 of cable 56. In an alternative form block 48 is carried on a lever biassed to contact-breaking position by a spring plunger, and rocked into contact making position either directly by the upper edge of the catch or by suitable link connection with the catch. In a further form, an insulated knob carried by the catch is adapted to engage between a pair of blade-spring fixed contacts. In another form, block 48 is carried by a vertically guided sliding member which is raised and lowered by an arm on the catch. Specification 506,380 is referred to.