Patent GB-832818-A (GB)
Title: Latch mechanism
IPC: E05B65/32
Filed: 1957-05-06
Abstract: 832,818. Latch fastenings. ROETHEL ENGINEERING CORPORATION. May 6, 1957 [May 31, 1956], No. 14312/57. Addition to 687,039. Class 44. A latch mechanism for a hinged door comprises in combination a support 10 having a main plate portion for disposition at the free edge wall of the door and having a flange 13 extending from the inner edge of the main plate portion, a latch device pivotally mounted on the main plate portion, a detent 20 mounted on the main plate portion for engagement with the latch device, a pivotal release lever 24 having an extension 28 extending towards the flange, a blocking lever 45 pivotally mounted on the support, yieldable means 51 normally urging the blocking lever into a non-blocking position and inner manually operable means movable in one direction to swing and retain the blocking lever against the action of the yieldable means into blocking engagement with the extension of the release lever to prevent actuation thereof from outside the door. The latch device consists of latch bolt 14 and a ratchet member mounted on a shaft 15 so that the bolt is on the outside of the support 10 and the ratchet member on the inside. They are urged in a clockwise direction as shown in Fig. 1 by means of a spring 42. The ratchet member 16 is provided with two abutments 17, 18 which are selectively engaged by a detent 20 which is pivotally mounted on the support 10. The abutment 18 is the normal latching abutment engaged by the detent 20 when the door is fully closed and the abutment 17 is a safety abutment. The detent 20 is mounted on the support 10 by means of a shoulder rivet 19 and pivoted to the same rivet is a detent release lever 24. This release lever has a downwardly extending arm 25 with a lateral flange 26 which is engaged by a plunger or the like moved by a handle or push button from the outside of the door. The release lever 24 has an inwardly extending arm 27 terminating in the extension 28 which passes through a slot 29 in the flange 13. The extension 28 is engaged by an arm 39 of a bell crank lever 37 which is pivoted to the flange 13 and which is moved from an inside door handle by a link 40. The arm 27 has an aperture 33 through which a lug 32 of the detent 20 passes, the lug being urged into contact with the lower edge of the aperture by a coil spring 30 secured to the rivet 19. Thus movement of the release lever 24 from either the inside or the outside of the door moves the detent out of engagement with the abutment 17 or 18 so that the latch bolt can pivot to release the door. When the door is closed the detent 20 is moved by the ratchet member 16 without moving the release lever 20 because of the clearance provided by the aperture 33. To prevent the door being opened by the outside handle the blocking lever 45 is provided; this is pivoted to the flange 13 and it is provided with two arms 47, 49. The arm 47 terminates in a hook portion 48 which is adapted to overlie the extension 28 of the release lever arm 27 and the arm 49 terminates in a lug 50 which underlies the arm 39 of the bell crank lever 37. The blocking lever 45 is urged by the spring 51 in such a direction that its arm 47 abuts the support 10. To prevent release of the latch mechanism by the outside handle or push button the bell crank lever is moved by the inside handle in the opposite direction to that which releases the latch bolt and its arm 39 then pivots the blocking lever so that the hook portion overlies the extension 28 of the release lever so that it cannot move to release the latch bolt. In view of the fact that the detent 20 can move independently of the release lever 24 the lever 45 can be moved to its locking position when the door is open and the door can still be closed. In a modification the detent 20 is riveted to the release lever 24 so that the blocking lever 45 can only be moved to its locking position when the door is closed since the extension 28 of the release lever arm 27 will lie in the path of the hook portion 48 of the blocking lever 45 when the door is open. The latch bolt 14 is a finger-like member having a camming engagement with a C-shaped striker 60, the free end of the latch bolt engaging a pocket 67 of the striker.