GB927222A - Improvements in or relating to releasable fastening devices - Google Patents

Abstract

927,222. Latches. WILMOT-BREEDEN Ltd. Oct. 15, 1959 [Oct. 22, 1958], No. 33712/58. Class 44. A push-button linkage for producing a positive turning movement of one of two interengaged latch parts during a releasing operation, comprises two interengaging lever arms, one provided with a cam surface which co-operates with a surface of the other with a camming action, the effective length of the lever arm transmitting torque to the lever arm which it engages progressively increasing relative to the effective length of the latter lever arm during an operative movement of the pushbutton. When the stem of an external push-button engages an abutment surface 13a of a lever 12 pivotally mounted on a back-plate 1 a lever arm 17 engages with a second lever arm 9 of a spring-loaded camplate 7 to the other side of which is integrally attached a cam 2. As the lever 12 rotates clockwise, Fig. 3, surfaces 18 and 19 of the lever arms contact with an increase in the effective length of the lever arm 17 and a decrease in the effective length of the lever arm 9. The increased leverage thus required to rotate the cam is offset by the pressure exerted by the door seals on the cam 2 through jaws 5 and 6 of a keeper engaging the cam, so that the resultant effort required on the push-button is approximately constant. A remote-controlled releasing mechanism includes a lever 24 whose arm 27 contacts the cam-plate 7 to rotate the cam. A locking lever 28 is also provided, which in its operative position prevents movement of an arm 15 of the lever 12. Specifications 864,305 and 871,895 are referred to.