Patent GB-762460-A (GB)
Title: Improvements relating to door latches
IPC: E05B63/22
Filed: 1952-11-13
Abstract: 762,460. Latches. GILL, W. A., WHISTLECROFT, A. W., and BELLI, C. G. Feb. 11. 1954 [Nov. 13, 1952], No. 28666/52. Addition to 664,451. Class 44. In an improvement in or modification of the latch described and claimed in the parent Specification, the catch for retaining the locking bolt in its locking position is a pivoted catch and is caused to move to its operative locking position by the release bolt on movement thereof produced by closing the door. Referring to Fig. 1, the release bolt 33 having a rounded outer end is slidable in a bore 31 of a body 1, 2, secured to the door 5, under the urge of a spring 40. The locking bolt 34 having at its outer end a roller 35 is slidable in another bore 32 in the body 1, 2 under the urge of a spring 41 the sides of the bore 32 being slotted to allow passage of the roller 35. The catch 45 has a pair of arms 56 joined by a portion 55, the arms being pivoted to the body 1, 2, by a pin 58. In the position shown the catch 45 engages behind a pin 63 on the bolt 34 and thus prevents its retraction. A pin 61 in one catch arm 56, Fig. 2, engages in a slot 62 in the bolt 33 such that when the bolt 33 is in its outermost position shown in dotted lines in Fig. 1, when the door is open, the catch will be moved to the position shown in dotted lines to release the pin 63. When the door is open both bolts 33, 34 are in the projected position and outward movement of the locking bolt 34 is limited by a pin 44 thereon engaging the body 1, 2. On closing the door the roller 35 engages either one of the small bevels 51 on a striker plate 46, Fig. 7, secured to the door post 47, Fig. 1, and thus the bolt 34 starts to retract against the urge of its spring 41. The release bolt 33 is operated to retract against its spring 40 slightly after the bolt 34 owing to engagement with either of the larger bends 52, Fig. 7, on the striker plate. As the release bolt retracts it moves the pin 61 and thus the catch 45, in an anticlockwise direction to a position in which it can fall under gravity. Such movement of the catch under gravity is delayed by the pin 63 on the retracting bolt 34 engaging under the catch portion 55. When however the locking bolt 34 is aligned with an aperture 50 in the striker plate it is shot by its spring 41, thereinto, and the catch then falls so that its portion 55 is behind the pin 63. The door can now only be opened by releasing the catch 45. This is effected by a pin 22 on a vertically movable slide member 18 which is urged downwardly by a spring 21. The member 18 engages with a transversely movable actuating member 17 provided with a recess cam surface coacting with the rounded end of the member 18. The ends of the member 17 are loosely connected, to allow of considerable free play to the upper ends of vertical handles on each side of the door, as described with reference to Fig. 5 (not shown), the lower ends of the handles being pivoted to the sides of the door. By pushing or pulling on either handle the member 17 moves to cause the slide 18 and its pin 22 to rise and lift the catch 45. Continued pressure on handle in whichever direction it is desired to open the door causes the automatic retraction of the locking bolt 34. When the door is opened the locking bolt is urged outwardly and the catch 45 is maintained in its free position (shown dotted in Fig. 1) by the outward movement of the release bolt 33. The handles may be arranged horizontally or in any other desired position and the catch may be operable by a safety bar as used on exit doors of public buildings. If desired, the latch may be positively locked by a member of a key-operated mechanism engaging the catch 45. The casing for the latch is formed of two members secured to the body 1, 2, viz. a U-shaped member comprising the back wall 10, Fig. 2, and upper and lower walls 8, 9, and an L-shaped member comprising the front wall 11 and end wall 12. The members 17, 18 are housed in a compartment formed by the wall 12 and a division plate 13, Fig. 1. Alternatively, the casing, apart from a removable cover plate, may be die-cast integrally with the body 1, 2.