Patent GB-1246441-A (GB)
Title: Improvements in locks
Inventor: BANHAM JOHN ANTHONY
IPC: E05B55/04
Filed: 1967-07-06
Abstract: 1,246,441. Locks. BANHAMS' PATENT LOCKS Ltd. 2 Oct., 1968 [6 July, ,1967], No. 31081/67. Heading E2A. A latch lock comprises a bolt member 10 movable by a key operated mechanism 6, a handle member 28 also arranged to move the bolt member through means 20 interconnecting it to the bolt member, said means being arranged to be disengaged when the bolt member is moved to an extended locking position from a partly extended latching position, so that movement of the head-operated member is ineffective to withdraw the bolt, and to be re-engaged when the bolt member is returned from the locking position by the key operated mechanism, and resilient means arranged to urge the bolt member toward the locking position. In the construction shown, the lock comprises a casing 2 securable to a door by screws 4 and the key-operated locking mechanism 6 is a cylinder locking mechanism securable to the door by bolts 8 and to the casing by a screwed member 8a; this cylinder locking mechanism extends completely through the door and the casing and is operable by a key inserted from either side of the door, The bolt member 10 includes a head which protrudes from the casing in the latching and locking positions and is biased to such positions by a spring 16 in a pocket 18 of the casing, the spring engaging a bar 12 fixed to the bolt member and which engages guides 14. The bar acts as a pivot for an end portion of a lever that constitutes the connecting member 20 the other end portion of the lever being formed as a hook which engages a notch 24 of a bracket 26 which is part of the handle 28. The handle is pivoted to the casing on a shaft 30 and is urged clockwise as shown in Fig. 2 by a spring 32. The arrangement is such that if the handle is pulled away from the door the bolt member is withdrawn to the fully retracted position. The cylinder lock mechanism comprises a cam 34 that can enter either of a pair of recesses 36a, 36b in the bottom edge of the bolt member and when the cam is rotated in the clockwise direction to retract the bolt member the latter and the lever 20 are displaced together; if the resistance of the spring 32 is too great for the handle 28 to follow this movement an oblique end face of the hook will ride upwards over the notch edge as the lever pivots upwards against the force of the spring 38 anchored between the lever and a pin fixed to the bolt member. To move the bolt member to the locking position the cylinder lock mechanism is rotated in the anti-clockwise direction as shown in Figure 1 and in this position the dead locking member 42 comes into operation. The member 42 is vertically displaceable in upper and lower channel form guides 44 of the casing and is urged downwards by a spring 46 which acts upon a pin 50 fixed to the member 42 which has a stump 52 which rests on a land 54 of the bolt member in the latching and retracted positions of the bolt member; as the cam 34 of the cylinder lock mechanism 6 rotates anti-clockwise it first strikes a leg 56 of the lever 20 to pivot the hook 22 upwards out of the notch in bracket 26 and it next engages a leg 58 of the deadlocking member 42 to lift the stump 52 above a step 60 of the bolt member at the end of the land 54 and also enters the recess 36b of the bolt member and displaces the bolt member to the locking position, further rotation releasing the dead locking member and the lever. The lever is lowered by spring 38 and now rests beyond the bracket 26 so that it is out of engagement with the notch and the stump 52 of the locking member enters a recess 62 in the bolt member so dead locking the bolt member. The cam also engages a bottom part of the dead locking member 42 and prevents the stump 52 rising out of the recess. When the key is turned clockwise the reverse operations happen and if the handle has been held pivoted outwards when it is released an oblique end face of the hook is struck by the end of the bracket and the handle will lift the lever and allow the hook to drop into the notch.