GB638589A - Improvements in or relating to locks - Google Patents

Abstract

638,589. Night latches. CHAMBERS, N. July 24, 1948, No. 28590/47. [Class 44] In a night latch provided with a key operated follower NP and a knob operated follower QR, a cylinder A is rigidly fixed inside the stem D of the operating knob K, a second cylinder E being provided with a slot G in one of its ends, to accommodate the key operated bar M of the lock. The cylinder E, which is a rotating fit inside cylinder A, has an extension F of reduced diameter, around which a spring H is coiled, the spring having one end anchored to each of cylinders F and A. One arm Q, of the knob operated follower, is notched, so that when the bolt is fully retracted by this arm, the notch is engaged by the rear end of the bolt assembly, to retain it in the retracted position after the knob is released. When bar M is rotated in one direction by the key, the follower arm N withdraws the bolt, cylinder E rotates, and cylinder A, being coupled by spring H, rotates follower QR, the notch in Q engaging the bolt tail, to keep it retracted as before. To free the bolt, the key is rotated in the opposite direction, and when follower arm P has taken the force of the bolt return spring, arm Q is rotated by the light spring H away from the bolt tail. Releasing the key now allows the bolt to project normally. The bolt may always be retracted by follower arms P or R, without the bolt being held retracted on releasing the key or knob. The cylinder A may be fixed to stem D of the knob K, by a longitudinal slot in the cylinder coacting with the projection which keys the follower QR to stem D.