Abstract: A lock mechanism for a dead bolt assembly. The lock assembly includes a conventional key actuated cylinder for mounting outside the door for extending and retracting the dead botl between a locked and an unlocked position. An exterior thumb turn assembly is accessible from the exterior of the door and includes a rotatable actuator arm which is connected to a pushing link for pushing the dead bolt from its retracted to its extended position. The exterior thumb turn, however, does not permit the retraction of the dead bolt, but only permits its extension.

Abstract: The cylinder lock of the present disclosure includes a cylinder housing having either two or three rows of cylinder holes therein. The cylinder holes are in communication with an elongated cylindrical bore in which is inserted a cylindrical plug having a single row of plug holes. The plug can be rotated to each of the two or three rows of cylinder holes in order to permit the exchange of various pins within the cylinder holes and thereby permit the recording of the lock. One modification of the invention utilizes a notch adjacent one of the plug holes for permitting the key to rotate in one direction, but for preventing the key from rotating in another direction. A further modification utilizes an enlarged pin in one of the rows of cylinder holes so as to permit an access key to unlock the lock once, but preventing the access key from unlocking the lock a second time.