Patent GB-877428-A (GB)
Title: Improvements in or relating to releasable fastening devices
Inventor: JEAVONS PHILIP SWINGEWOOD
IPC: E05B65/32
Filed: 1956-10-16
Abstract: 877,428. Latch fastenings. WILMOT-BREEDEN Ltd. Oct. 16, 1957 [Oct. 16, 1956], No. 31528/56. Class 44. A releasable fastening device comprises a pivotally mounted latch member 16, a striker 11 having two portions 18, 19, one of which 18 has opposite side surfaces respectively forming a cam surface 22 engaged by the latch member in the latching position and a guide surface facing a guide surface formed on the other striker portion, and a further member 12 fixed relatively to the pivot axis of the latch member and arranged to be received and guided between the guide surfaces during a latching operation, on fastening, the striker and latch member initially engaging to turn the latter in one direction prior to the latch member turning in the opposite direction to the latching position and the arrangement being such that when the device is latched any tendency for relative movement of the latch member and striker in the opening direction, causes the latch member to wedge against the cam surface with the further member engaging the guide surface on the one striker portion to provide a wedging reaction. As shown, a plate 15 is adapted for attachment to the door edge and pivotally mounts on a pin 17 the latch member 16 which has a pin 13 projecting through an arcuate slot 14 in the plate 15 to engage the upper surface of the striker 11 which is C-shaped and intended for attachment to the door frame. The plate 15 also carries the member 12 which vertically locates the door during the closing operation; the inside surfaces of the portions 18, 19 are flared to ease the member 12 into the opening 20 between them. The upper surface of the portion 18 is provided with two teeth 23, 24, forming the cam surface, the latch pin 13 either engaging behind the tooth 23 in the fully latched position or if the door has not been fully closed, behind the tooth 24 which provides a safety latched position. The latch pin 13 is released from the teeth 23 or 24 by either an inside handle or an outside push-button. The inside handle moves a bell-crank lever 32 which is pivoted on a portion 34 of the plate 15 which is at right angles to the remainder of the plate. One arm 35 of the bell-crank lever engages an edge 36 of the latch member 16 and causes it to pivot to the release position. The push-button has a shaft 37 the inner end 38 of which presses on a platform 39 of a contactor 28 which is mounted on the pivot pin 17 of the latch member; pushing the push-button causes the contactor 28 to rotate and a peg 29 carried by it engages an edge 30 of the latch member 16 and causes it to rotate to release the pin 13 from the striker. To prevent the latch pin being released from the striker by pressing the push-button, the push-button can be turned by means of a key and this causes a projecting portion 40 on the shaft 37 to raise the contactor 28 so that the peg 29 is lifted clear of the edge 30 of the latch member to prevent depression of the push-button operating the latch plate. A self-centring spring is provided in the push-button mechanism and the contactor is indexed in its two positions by a spring 31a. The contactor 28 can also be raised to lift the. peg 29 clear of the latch member by rotating the inside handle in the opposite direction to that which unlatches the device, this causes the arm 35 of the bell-crank lever to engage an edge 42 of the contactor 28 and so raise it. When the inside handle is moved in the unlatching direction the arm 35 of the bell-crank lever engages an edge 43 of the contactor to lower it to its latch member operating position. To prevent the door being closed with the contactor 28 in the raised position a bell-crank lever 44 is provided on the plate 15; on closing the door the latch pin 13 engages the striker 11 and rotates the member 16 in an anticlockwise direction; this causes an edge 47 of the member 16 to engage an arm 48 of the lever 44 and the arm 49 of the lever is brought into contact with the peg 29 of the contactor 28 to move the latter into engagement with the latch member. The latch pin 13 is urged into engagement with the upper portion 18 of the striker by means of a spring 27 but in the event of spring failure the pin engages the striker under the action of gravity. The shape of the rear surfaces of the teeth 23 and 24 of the striker is such that forces between the latch pin and the striker pass substantially through the axis 17a about which the latch member 16 is movable and no torque is exerted on the latch member. In a modification, Fig. 5, the pin 12 is provided with a head 12b and opening 20 in the striker is stepped so that movement between the striker and pin 12 when the device is installed in a vehicle is limited.