GB892310A - Improvements relating to locks, latches and the like - Google Patents

Abstract

892,310. Latches. SHUTE, A. A. T. May 19, 1958 [May 20, 1957; Oct. 14, 1957], Nos. 15965/57 and 32056/57. Class 44. A latch or lock, which offers a high degree of resistance to interference by unauthorised persons, comprises an L-shaped casing 1 having two principal guideways 2, 3 which are at right angles to each other and accommodate respectively a slidable lock bolt 4 and a slide 5 for actuating the latter. A compression spring 8, located between the rear end of the bolt 4 and a wall of the casing, urges the lock into its locking position and a manually operable knob 9, screwed into the bolt and having its shank passing through a longitudinal slot in the casing, is provided for withdrawing the bolt. The bolt and the slide are interconnected by a bell-crank-lever 11 the arms of which, carrying rollers 14, 16, engage respectively in a recess 15 in the bolt 4 and a groove in the slide 5. The bell-crank-lever 11, fitted at its elbow upon-a trunnion 12 journalled in a bearing block 13 secured centrally in the casing 1, operates between a side face of the block 13 and an inside wall surface of the casing. The slide could be arranged to engage behind and deadlock the bolt, preferably however, a dead locking member 21 is provided which is slidable in a guideway 22 parallel to the guideway 3 so that a tongue on its inner end engages in a recess 24 in the bolt 4 when the latter is shot. For operating the slide 5 and the dead-locking member 21 each is provided with a stem 18 or 23 having a longitudinal key-way 19 with a short transverse key-way leading therefrom for engagement with a radial projection 20 on the inside of a tubular key 6 when the latter is slidden over the respective stem. In the embodiment shown or in an alternative arrangement wherein a solid key fits within a hollow stem a large number of alternative arrangements can be provided, each necessitating a different key, by varying the position of the radial projections, the length and bore of the key or stem, &c. Spring- loaded catches 25, 26 housed in a guideway 28 in the bearing block 13 project from the guideway and engage behind the slides 5, 21, when the latter are in their innermost positions the catches 25, 26 being disengaged by the full insertion of a key. A spring-loaded slide 29 in a plate 30 secured to the casing 1 protects the outer ends of the stems 18, 23, the slide having openings 31, 32 which are chamfered at one edge which is engaged on insertion of a key into the respective keyhole to displace the slide transversely.