GB896146A - Improvements in or relating to releasable door fastening devices - Google Patents

Abstract

896,146. Door latches. WlLMOT-BREEDEN Ltd. Nov. 25, 1959 [Dec. 22, 1958], No. 41259/58. Class 44. A releasable door fastening device embodies a locking mechanism which acts to obstruct and prevent releasing movement of a releasing mechanism adapted to be operated by a releasing member and having a load-limiting connection through which the effort of the releasing member is transmitted, this connection being such that the maximum load which can be applied by the releasing member to the locking mechanism when locked is insufficient to distort the latter sufficiently for the device to be released or irreparably damaged. In the car door latch shown, actuation from inside the car to move the locking mechanism lever 19, 20 such that the arm 19 is positioned to prevent a releasing movement of a lever 7 prevents normal inward movement from outside the car of a push button releasing member engaging a lever 15 but if the button is struck a heavy blow or otherwise forced inwardly a frangible pin 16, transmitting the torque from the lever 15 to the lever 7, fractures, thus allowing free movement of the button and lever 15 in a still locked door. The device comprises plates 4 and 5 between which are rotatably mounted co-planar levers 6, 7 and the lever 15. The levers 6, 7 have cam contacting edges 6a, 9a and are connected by a spring 10 tending to urge the lever 6 into door locking position wherein a cam 2, which is fixedly mounted on the rotatable pivot 3 mounting the lever 6, engages a G-shaped keeper 1 on the door frame pillar. The lever 19, 20 may be actuated from within the car to move the lever 6 through a stud 23 thereon such that the cam 2 rotates and unlocks the door. Specification 871,895 is referred to.