GB746547A - Improvements in and relating to door latch mechanism - Google Patents

Abstract

746,547. Door latches. ROETHEL, J. H. March 3, 1954 [May 27, 1953], No. 6209/54. Class 44. A door latch mechanism for a swinging door, Figs. 1, 2 and 3, comprises a supporting plate 10 with a side flange 11, a rotary bolt 12 mounted on plate 10 and secured to a ratchet wheel 14, a detent 15 slidably mounted on plate 10 to engage the ratchet wheel 14, outer manually operable means to slidably actuate the detent 15 to disengage it from the ratchet wheel 14 and including an actuator 19 mounted on the plate 10 which has a part 21 in opposed relation to the detent 15 but permitting separate movement of the detent 15 independently of the actuator 19, and an inner manually operable member pivoted on the plate 10 and having a blocking portion 29b which can be moved by inner operation means into a position to block movement of the actuator 19. The actuator comprises a lever 19 which can be rotated anticlockwise by external means, such as a pushbutton 25, to depress the detent 15 against a spring 26 by engaging the upturned lug 24 and thereby release the bolt 12 for clockwise, or unlatching, rotation. The blocking lever 29 can be moved between two positions by a link attached to end 38, or by a cylinder lock eccentric working in slot 37, and in the position shown prevents actuation of the latch by pushbutton 25. When so blocked the latch may still be operated by means of a bell-crank lever 31 worked from inside the door, by a link attached to end 32, to depress the detent 15 by engaging the portion 34, whereupon the blocking lever is moved out of the way by the downward movement of arm 41 of the detent 15. This automatic unblocking of the mechanism also occurs when the bolt is latched as anti-clockwise rotation of the ratchet wheel 14 cams the detent 15 downwards. Bolt 12 engages a keeper 42 (Fig. 4, not shown) which is constructed in accordance with that of Specification 667,873. A modification of the latch suitable for a rear door of a motor vehicle, Fig. 5, differs in that the blocking lever 56 can be operated only from inside the vehicle and cannot automatically be unblocked, and when in its blocking position it also prevents unlatching by the inner operable bell-crank lever 32 due to the extended arm 54 on the actuating lever 53 which underlies the arm 33 of the lever 32 and replaces the portion 34 of the detent of the first embodiment.