GB1140725A - Improvements in or relating to latch sets and lock sets - Google Patents

Abstract

1,140,725. Latches and locks. JOSIAH PARKES & SONS Ltd. 2 June, 1966 [18 June, 1965], No. 25801/65. Heading E2A. A latch or lock set comprising a latch or lock having a casing 14 in which is mounted a latch 'bolt spring biassed to an extended position and a striking plate 10 having a latch bolt Hole 11 to receive the head 16 of the latch bolt when the latter is extended and when the latch or lock is mounted in a door and the striking plate on the door frame, the latch bolt having a bevel 20 at its head which co-operates with the lip 13 of the striking plate when the door is slammed 'to 'retract the latch bolt .against the .spring bias, the head of the latch bolt as the door reaches its fully closed position on slamming entering the hole in the striking plate under the spring bias so that an engaging surface 27 of the head opposite the bevel is forced to engage one side 28 of the latch bolt hole to hold the doo.r closed and wherein the head of the latch bolt has a first part providing .said engaging surface and a flange or flanges projecting from the first part and forming a second part providing said bevel and wherein in addition to the bevel and the. lip the head and the striking plate have portions which engage with a wedging action when said head projects into the latch bolt hole a distance considerably less than the full shoot of the latch bolt to force the engaging surface of the bolt head against said one side, at least one of said portions having a surface which is inclined relative to the direction of motion of the other .portion as the bolt head enters said hole, said inclination being such that when the latch or lock .said is installed and a 'door closed a force applied to the door tendÝng to move said engaging surface away from said one side of said hole will not cause retraction of the bolt head against the spring bias. In the construction shown the wedging portion of the striking- plate is a block 23 which projects into the hole 11 and presents an inclined wedging surface 25; the bolt head is of channel shape so that it has two flanges, the two flanges being shaped to provide the bevel and the edge 26 of the web which constitutes the first part providing the wedging portion. In a modification the surface of the web of the channel is inclined and engages with an edge of a modified block of the keeper. In another construction the bolt,is T shaped in cross section and the stem of the T forms the flange and is shaped to provide the bevel; the head of the T provides two edges which engage inclined surfaces of a block which forms part of the striking plate, the block being recessed between the surfaces to provide clearance for the bevel. In a modification of this construction the head of T provides two inclined surfaces and the block two edges for engaging the inclined surfaces of the bolt head.