Patent GB-872621-A (GB)
Title: Improvements in or relating to releasable fastening devices
Inventor: JEAVONS PHILIP SWINGEWOOD
IPC: E05B65/32
Filed: 1956-10-16
Abstract: 872,621. Latch fastenings. WILMOTBREEDEN Ltd. Oct. 16, 1957 [Oct. 16, 1956], No. 31527/56. Class 44. A releasable fastening device comprising a striker 21, a pivotally mounted latch member 31 having a transversely projecting portion 27 which in use constantly trails the axis of the pivot during a latching operation in which the projecting portion engages the striker to produce pivotal movement of the latch member in a positive angular direction into the latching position, and manually operable means which operate to turn the latch member in the reverse angular direction to said positive angular direction to release the fastening device. The device comprises a plate 28 which is fixed to the inside surface of the door edge and on which is pivotally mounted the latch member 31. The portion 27 is a pin which extends through an arcuate slot in the back plate and through a similar slot in a guide plate 22 which is fixed to the outside surface of the door edge to engage the striker 21 which is G-shaped. The guide plate has flanges arranged in a substantially dovetail shape to engage the upper and lower surfaces of the striker to vertically position the door. When the door is unfastened the latch member is normally urged by a spring 38 to a position such that the latch pin 27 is at the upper end of the arcuate slots in the back plate and guide plate; in this position when the door is moved in a closing direction the latch pin engages the upper jaw 57 of the striker and is urged slightly downwardly by a bulge 58 and when the bulge has been passed it is returned by the spring 38 to the upper end of the arcuate slots. This is a safety latching position and reverse movement of the door only causes the latch pin to bear against the inner periphery 58a of the bulge 58 without sliding over the bulge. Further closing movement of the door causes the latch pin to engage a cam surface 55 of the striker which urges the pin downwardly against the action of the spring 38 until it occupies the lower end of the arcuate slots; in this position the spring 38 has passed beyond the pivot centre of the latch plate and tends to retain the striker pin in the lower end of the slots. Opening of the door is prevented by the engagement of the latch pin with the part 56 of the striker; this is the fully latched position. In both the fully latched position and in.the safety latched position the forces between the latch pin and the striker pass substantially through the centre of the pivot 34 of the latch plate 31 so that no torque is exerted on the latch plate. In the event of the latch pin being at the lower end of the slots when the door is being closed, it engages the outside surface of the lower jaw of the striker and rides up the surface 60 against the pressure of the spring 38 which during this movement will move over the pivot centre of the latch member and throw the latch pin across to the cam surface 55 after which latching continues as before. The latch pin is released from the striker by moving the latch member in an anticlockwise direction. It is moved in. this direction from the outside of the door by means of a push button 64 pressure on which causes its shaft 43 to engage the end of a pivoted contactor 32 to rotate the contactor. The contactor engages a peg 35 on the latch member to rotate the latch member. To release the latch pin by means of an inside handle the contactor 32 is rotated by means of a remote control lever 33 which is provided with an arm 45 connected to the inside handle formed with two recesses 49, 50, an extremity of the contactor 32 being engaged in the recess 49. The recess 50 has two faces 52, 52a which co-operate with a locking lever 53. The lever 53 is pivoted to the back plate and movement of the inside handle in a reverse direction to that which causes the latch pin to be released from the striker causes rotation of the locking lever. The locking lever carries a boss 70 having a bore 71 through which the push button shaft 43 passes and a transverse pin 72 carried by the push button shaft engages a V-shaped groove in the boss 70; thus when the locking lever is rotated by the inside handle it also rotates the push button shaft 43 and the part 42 of the push button shaft which engages the contactor 32 is rotated out of engagement with the contactor so that subsequent depression of the push button is ineffective to rotate the contactor and release the latch pin. The push button can also be turned from the outside of the door by means of a key so that locking the door from both inside and outside is possible. To prevent the locking lever being moved to the locking position while the door is open an edge portion 76 is provided on the latch plate which with the door open prevents movement of the remote control lever to the locking position by preventing movement of its extremity 51. The door can however' be locked without the use of the key when it is open by moving the latch pin 27 so that it lies in its lower position, the remote control lever 33 can then be moved to its locking position. The guide plate 22 and the striker 21 can be modified as shown in Fig. 8 by providing the guide plate with a flange 23a and a recess in the striker to limit relative movement between the striker and guide plate in a direction fore and aft of the vehicle. In an alternative construction the remcte control lever and locking lever are modified, the locking lever being provided with a lug which when it is in its locking position prevents movement of the contactor. In a further modification the locking lever is dispensed with and the remote control lever is arranged to prevent rotation of the latch member when it is moved to a locking position.