GB232717A - Improvements in and relating to door locks - Google Patents

Abstract

232,717. Johnston, G. W. P. Feb. 5, 1924. Latches, sliding, and preventing opercation of. - A latch bolt is held in intermediate or latching position by a pawl pivoted thereon and engaging a stop on the casing. Slamming of the door releases the pawl and allows the latch bolt to shoot into locking position. The follower retracts the bolt by engaging the pawl, which it also causes to reengage the stop. The bolt a with a bevelled conical nose a<1> has a recess in which is pivoted the pawl k, i, a hook of which normally engages a stop s on the plate q fixed to the casing, to hold the bolt in latching position. When the door is slammed ,the bolt a is pushed inwards by the striking plate, releasing the pawl from the stop s and allowing it to be rocked by the spring o so that the bolt can shoot fullv out into the staple to secure the door. The bolt mav be blocked in this position by an arm v turned by a square key to engage a recess u. The arm v may be formed upon the barrel 19 of a lock 20 as shown in Fig. 7. The bolt is withdrawn by the follower l which engages the arm k of the pawl and pushes it against a stop x on the bolt and also causes the pawl hook to re-engage the stop s. The pawl hook may be disengaged from the stop s, on slamming the door, by gravity, or the blade spring o shown in Fig. 2 or the spiral spring o<x> shown in Fig. 6.