Patent GB-741025-A (GB)
Title: Improvements in or relating to latch mechanism
Inventor: RAYBURN ALDEN GRANVILLE
IPC: E05B55/12
Filed: 1953-09-14
Abstract: 741,025. Door latches. CARTER, V. M. Sept. 14, 1953, No. 25299/53. Class 44. A tubular lock set includes a latch bolt subassembly, an actuator 40 and a casing 30 adapted to operably mount and contain the sub-assembly and the actuator, the subassembly comprising a striking head 15, a hollow shaft 35, attached to the striking head and having opposite flat sides with oppositely located longitudinally extended slots 75, 76 therein, a reciprocator 60 having a pivot hole intermediate opposite ends and a tubular pivot pin 681 in the hole and mounted slidably in the slots 75, 76, to retain the reciprocator in the shaft, the shaft having a shoulder 64 in contact with one end of the reciprocator, the actuator being hollow and elongated and adapted to be slidably mounted around the shaft and in engagement with the other end of the reciprocator. The lock set is intended for a door, the casing 30 being attached at right angles in a bore in the door to a cage, also contained in a bore, for the spindles which are operated by the door handles. The casing 30 is stamped from sheet metal in two halves which interlock longitudinally and the hollow shaft 31 and actuator 40 are also made of sheet metal. The inside of the actuator 40 acts as a guide for the shaft 35 which slides within it and the actuator 40 is slidably guided in the casing 30, the rear of the casing having flat sides 33<SP>1</SP> for this purpose; the front part of the casing is of cylindrical cross-section with a flange 57 at its front end which is trapped between a finish plate 38 and a back plate 55. The head 15 is provided with recesses which engage projections 48 on the shaft to secure the shaft to the head and has a shoulder 37 which butts against the plate 38 to prevent its leaving the casing. A central guide 80 is provided supported by the tubular pin 68<SP>1</SP> which in turn is supported by a solid pin 68 engaging the casing 30 at both ends and both pass through apertures in the shaft 35 and actuator 40. This guide has two oppositely directed arms 83, 84, the arm 83 slidably engaging an aperture in a wall 49 provided in the interior of shaft 35 and the arm 84 slidably engaging an aperture in the end wall 44 of the actuator 40. Coiled compression springs 85, 87 surround the arms and are trapped between the centre of the guide and the walls 49, 44 respectively. The actuator retracts the head by being moved in the opposite direction to that in which the bolt head moves when retracting, the actuator being moved by arcuate ends of the spindles engaging its end wall 4. The movement of the actuator 40 is conveyed to the latch shaft 35 by the reciprocator 60 which is pivotally mounted intermediate its ends on the tubular pin 68<SP>1</SP> and surrounds the centre part of the guide 80. One end 65 engages the shoulder 67 on the actuator and the other 63, a flange 64 on the shaft 35. The provision of the tubular pin 68<SP>1</SP> facilitates assembly of the guide 80, shaft 35, reciprocator 60 and spring 85. The latch is provided with a slidable dead bolt 100 which when the bolt head 15 is engaged in the keeper recess, is actuated against a spring 110 into the latch casing 30 by butting against the keeper striking plate. This retraction allows the cranked arms of a forked lever 101 to engage the rear of the head 15 to prevent it being retracted by using an implement when the door is closed. The lever 101 is located by a portion 107 which extends into an aperture in the casing 30 and it is urged into engagement with the head 15 by the spring 110 which surrounds a shank 102 of the dead bolt and is trapped between the end of the dead bolt and the portion 107 of the door 101. The dead bolt has two integral wings 115 (not shown) and 114 which each engage one of the arms of the lever 101. When the head is free of the keeper the end of the dead bolt is pushed out of the casing by the spring 110 and the wings then engage the cranked ends of the arms of the lever 101 and move them away from the rear of the head so that when the head engages the keeper it can be retracted into the casing; when the head is in the keeper recess, the dead bolt is held retracted by the striker plate as previously stated so that the arms of the lever engage the rear face of the head. To allow the head to be retracted by the actuator 40, an end 116 of the actuator is arranged to engage a part 117 of the lever to move the arms away from the bolt head before the bolt is moved by the reciprocator 60.