Security lock for doors

摘要

A locking device mountable within a door in a door frame, comprises a casing including a pair of side plates, a toothed-wheel rotatably disposed between the side plates, and a plurality of locking bars coupled to the toothed-wheel and projectable thereby into locking engagement with the door frame. The toothed-wheel is formed with a cam surface for each locking bar, each locking bar carrying at its inner end a cam follower movable along the respective cam surface of the toothed-wheel. The side plates are formed with guiding slots for each locking bar guiding the movement thereof such that the rotation of the toothed-wheel in one direction projects the outer ends of the locking bars from the door into locking engagement with the door frame, and the rotation of the toothed-wheel in the opposite direction withdraws the locking bars into the door.