GB549395A - Improvements in rim latch - Google Patents

Abstract

549,395. Latches. ZION, A. June 25, 1941, No. 7975. [Class 44] In a door latch (shown as a night latch) in which the bolt is withdrawn by a retractor pin which can also dead-lock the bolt in fully shot position, the pin 46 carried by a radial arm operable by knob 49 is biased by spring 51 to the deadlocking position, Figs. 4, 5, in which it rests against a stop 50 and is positioned in line with the rear end of a bar 35 projecting rearwardly from the bolt head, and it also cooperates with recesses in the edge of an aperture 43 in the bolt tail 34 so that the bolt may be moved to a partly retracted position from which it is releasable only by pushing in the bolt as by closing the door, the bolt and pin then returning to the fully shot dead-locked condition shown, or may be further moved to a fully retracted position from which it returns to the partly retracted position above referred to on release of the knob, or may be still further moved to a fully retracted position in which it is held until released by a reverse movement of the knob. As shown, the bolt has two lateral recesses 44. 45 separated by a hump 45a, Fig. 3. A- similar pair of symmetrically disposed recesses 47, 48 are also provided so that the bolt is reversible for right-hand or left-hand use. When pin 46 is moved clockwise, Fig. 4, it withdraws the bolt until it snaps over a shoulder 57 into recess 45. In this condition the bolt is partly retracted and is held by shoulder 57 preventing return movement of the pin. When the bolt is pushed in, shoulder 57 releases the pin which is then moved anticlockwise by spring 51 until arrested by the upper edge of bar 35. When the bolt subsequently shoots, the pin rides over the end of bar 35 to deadlocking position. If the pin 46 is given a further clockwise movement it rides over hump 45a into recess 44 as in Fig. 3. In this position the bolt is fully retracted so that the door may be opened, but when the knob is released pin 46 returns to recess 45 holding the bolt in the partly retracted position above described. If however, pin 46 be given a still further clockwise movement, the bolt is further retracted and the pin returns over hump 45a into recess 45 and holds the bolt in fully retracted position until the pin is given an anticlockwise movement by the knob. The bolt tail 34 and bar 35 are conveniently formed integral as a sheet-metal stamping secured at 36 in a groove at the rear of the bolthead 32. The spring 41 which shoots the bolt is disposed around bar 35 in compression between the bolt head and a washer 42 against a fixed abutment 40 which also has a groove guiding the free end of bar 35. Outside operation is effected by a cylinder lock 56 the connecting bar 55 of which rotates a member 53 journalled in the cover plate 22 of the casing and having a pair of arms 52 (one shown) one of which engages pin 46.