GB967548A - Improvements in or relating to door fastenings - Google Patents

Abstract

967,548. Latches. WILMOT-BREEDEN Ltd. Nov. 7, 1960 [Jan. 5, 1960], No. 33573/60. Divided out of 953,052. Heading E2A. A door fastening of the link latch type comprises a pivotally mounted latch piece 6 and a keeper 1 with which the latch piece engages, and embodies a spring loaded toggle linkage which is extended when the latch piece is in the latched position and retains the latch piece in that position, release means arranged to collapse the toggle linkage to release the fastening, and a trip lever pivotally mounted intermediate its ends and having its outer end arranged for engagement with the keeper as a result of door closure to cause the inner end of the lever to act directly on the linkage to trip the fastening. In the unlatched position, Fig. 1, of a fastening, a toggle linkage formed by a link 19 and a lever 13, pivoted at 14, is retained in its extended position by a spring urged rod 26. Downward movement of the keeper 1 rotates a trip lever 30 about its pivot 24 to collapse the toggle linkage 19, 13 by shifting its pivot point 18 overcentre. A second toggle linkage composed of the link 19 and a link 22 is thus extended and the latch 6 is rotated about its pivot 24 by a link 15 to retain the keeper in its latched position. Unlatching is performed by moving the rod 26 to the left by a suitable handle to collapse the toggle linkage 19, 22. The fastener of Fig. 3 is similar, but is unlatched by rotational movement of a rod 37 clockwise from the position shown to collapse a toggle linkage formed by a link 33, pivoted at 35 to the latch piece 6, and a lever 36, and to thus allow the latch piece 6 to rotate free the keeper 1. The latch piece 6 is retained in its unlatched position by a second toggle linkage formed by the link 33 and the latch piece 6, a tension spring 38 holding the toggle linkage in its extended position as it did with the first toggle linkage. Movement of the keeper towards the latched position rotates a trip lever 49, pivoted at 41 to the latch piece and having a cut out 40 within which an extension of the pivot 34 can move, to collapse the toggle linkage 6, 33 by shifting the pivot extension upwardly to the position shown.