Security lock for doors

Claim 1

A rim locking device mountable within, and adjacent to, one side of a door in a door frame, comprising: a casing including a pair of side plates; a cylinder rotatably disposed between the side plates and having a keyhole for receiving a key to rotate the cylinder; a gear carried by the outer surface of said rotatable cylinder; a toothed-wheel rotatably disposed between the side plates and meshing with said gear for rotation thereby upon rotation of the cylinder by the key; and a plurality of locking bars coupled to said toothed-wheel and projectable thereby into locking engagement with the door frame, one of said locking bars being a short locking bar projectable from and withdrawable into said one side of the door, the remaining locking bars being long locking bars projectable from and withdrawable into the remaining three sides of the door, said toothed-wheel being 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, at least one of the side plates being formed with a guiding slot 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; said device further including a tongue projectable from said one side of the door into a recess in the door frame, a spring urging the tongue to its projecting position, a lever pivotable to withdraw the tongue from the door frame, and an abutment carried by said toothed-wheel for pivoting the lever to withdraw the tongue when the toothed-wheel has been rotated in the direction to withdraw the locking bars.