GB547016A - Improvements in and relating to night latches and similar fastenings - Google Patents

Abstract

547,016. Latches. CHUBB & SON'S LOCK & SAFE CO., Ltd., and START, P. W. March 20, 1941, No. 3809. [Class 44] In a latch of the type which is automatically dead-locked by co-operation of the bolt with the striking plate or keeper on closing the door &c. dead-locking is effected by a deadlocking lever and a pivoted detent which holds the lever cut a-f the path of the bolt after retraction from and return to, normal locking position, the detent being tripped by the bolt, when the door is slammed, to free the lever and allow its return to dead-locking position. Fig. 1 shows the application to a levertype night latch in which the bolt a may be retracted from outside by a key operated runner plate b (locked by the usual lever tumblers c) or from inside by a handle-operated singlearmed follower d. As shown, a dead-locking lever f has its free end p raised into locking position behind the rear shoulder of bolt-head a<1> by spring f<1>, the free end r of a pivoted detent g resting in a recess in the lever and serving as an abutment to limit upward movement of the lever. A lever projection n<1> locks the bolt if not fully shot. When the bolt is retracted lever f is depressed by a cam arm d<1> on follower d acting on a cam hump m on the lever or by a pin q on runner plate b acting in a cam slot h in the lever. In either case the lever is held depressed and clear of the bolt head by the end r of the detent moving to the left under action of a spring g' till arrested by a lever projection n with the end engaging a stepped shoulder o on the lever. The bolt n<1> is thus freed for retraction and for return movement'to the fully shot position when the key is withdrawn or the handle released. On subsequent closure of the door inward movement of the bolt trips the detent by engagement of the bolt head with a hump s on the dent. A similar arrangement is described in a night-latch in which a cylinder lock operating the follower replaces the lever lock shown. A modification is also described of cylinder lock type in which the follower is twoarmed so that the bolt is retracted by rotation of the handle in either direction, and in which the locking lever is of L form with its vertical arm resting against the front of the follower so that the lever is rocked to release the bolt when the follower is rotated either way. A lever lock form is also described having a two-armed follower and in this case the dead-locking lever is of inverted T form with its vertical arm against the front of the follower, its forwardly extending horizontal limb acting as the locking- lever proper and its rearwardly extending arm engageable by a hook-ended detent disposed behind the follower and tripped by the bolt tail.