Patent GB-782916-A (GB)
Title: Improvements in locks
IPC: E05B55/00
Filed: 1954-11-25
Abstract: 782,916. Locks; sliding latches. BACKHOUSE, H. T. Nov. 25, 1954; Feb. 11, 1955; Aug. 17, 1955], Nos. 34167/54, 4103/55, 23748/55. Class 44 Relates to locks of the kind embodying a bolt slidable with respect to a casing between a locking position in which it projects from the casing and an unlocking position in which it is withdrawn, at least partly, into the casing an an arm rotatable within the casing by means of an external handle, in one direction from a neutral position to withdraw the bolt into the unlocking position and in the other direction to a position in which it acts as a positive stop in the path of the bolt to hold the bolt in the locking position. According to the invention, an internal catch is provided which is automatically engageable with the locking arm when the arm is moved to the holding position, a removable key being required to effect disengagement of the catch from the arm. In the arrangement according to Fig. 3 in which a latch bolt 22 is withdrawable from one side of the door by a handle-operated arm 27 and from the other side of the door by a handle-operated arm 28 and in which the arm 28 may be rotated in the other direction against a spring 30 to lock the bolt 22 in the shot position, the arm 28 is retained in the locking position by a latching engagement with an arm 34 which is releasable only by key operation of a cam 40. The cam 40 may be operated by a removable key, for example of square cross section, engaging the cam directly, or the cam may be operated by a cylinder lock. The handle-operated arm 27 is prevented from blocking the bolt by a stop 29. The bolt may be retained in the retracted position by a finger-operated slide 45 accessible from the edge of the door. In another arrangement, Figs. 5 and 6, the bolt 22 is withdrawable from the shot position and is lockable, from either side of the door by a single handleoperated arm 50 which is retained in the locked position by a catch lever 62 The lower end of the lever 62 engages a cam 60 which is rotatable from one side of the door, to release the arm 50 by a key operated cylinder lock 57. The lever 62 is also releasable from the other side of the door by means of a cam 65 which is operated by a handle 64. A locking lever 70 i soperative by key operation of the cam 60, to engage a stop 71 on the lever 62, to positively hold the lever 62 in the locking position, the locking lever being disengaged upon operation of the cylinder lock to free the arm 50. The cams 60 and 65 may have the same configuration. In a further arrangement, Figs. 7 and 8, the locking lever 70 is replaced by a device comprising a rod 82 arranged at the front of the lock casing for vertical and rotational movement, and carrying a pin 85, 85a, the end 85a being engaged in a right-angled slot at the edge of the door. The arrangement is such that when the end 85a is within the horizontal part of the slot, the other end 85 lies in the path of the catch lever 62 to lock it in its latching position. Vertical movement of the rod 82 also blocks the bolt 22 in retracted position and this replaces the slide 45. When the lock is used as a rim lock, the cylinder lock may be attached to the face of the lock casing and protrude through the door thickness. In order to provide adjustment for doors of different thickness a flanged ferrule may be screwed on to the cylinder lock to engage, with the flange, on the opposite face of the door. In a modification, the handle 64 may be attached directly to the arm 50. In a further modification, the lever 70 or the rod 82 may be omitted, the arm 50 then, being movable into engagement with the lever 62 from either side of the door and means being provided at both sides of the door for releasing the catch, the means at one side requiring a key. Specification 496,776 is referred to in the first Provisional Specification.