Abstract: A key for a lock of the plunger operated type in which an elongated housing has an internal axially movable plunger which releases locking elements when moved toward the open end of the housing, said key having a body with elongated fingers extending forwardly from the housing and an elongated mandrel disposed between the fingers. A finger depth limiter or spacer is disposed at the rear end of the fingers and protrudes forwardly from the foremost face of the key housing for abutting a portion of the lock to limit the distance the fingers can extend into the lock. In one embodiment of the invention an axially adjustable cap is mounted on the forward end of the housing to allow adjustment of the amount the spacer projects from the housing.In one embodiment of the invention internal structure is provided that allows the fingers to shift forwardly a predetermined distance if the forward end of the housing is removed by grinding in an effort to modify the key for use in locks with which it is not intended for use.

Abstract: A key for a lock of the plunger operated type in which an elongated housing has an internal axially movable plunger which releases locking elements when moved toward the open end of the housing, said key having a body with elongated fingers forwardly from the housing and an elongated mandrel disposed between the fingers. A spacer is disposed at the rear end of the fingers and protrudes forwardly from the foremost face of the key housing for abutting a portion of the lock to limit the distance the fingers can extend into the lock. The housing has a head portion which is axially adjustable in relation to the spacer to vary the amount the spacer projects forwardly from the housing.In one embodiment of the invention internal structure is provided that allows the fingers to shift forwardly a predetermined distance if the forward end of the housing is removed by grinding in an effort to modify the key for use in locks with which it is not intended for use.

Abstract: This invention relates to a screw lock, characterized in that the screw key screws into a keyway, and the slots on the top ring screw of the screw key provide a convex-concave match with switch points in the cylinder. The screw key is then pushed in and turns the cylinder to effect locking and unlocking. The keyway of this invention is adapted to accept the spiral screw shape, and accordingly, the form and the mechanism of the switch points are not seen. Thus, the form and mechanism of the switch points in the cylinder is unknown. Also, conventional keys or wires cannot be inserted into the spiral screw hole. In case other keys are inserted into the keyway, the set points in the cylinder prevent the key form being further pushed in and prevent turning of the cylinder to effect unlocking.

Abstract: An improved bolt mechanism for use in a rotary lock has a fixed transverse pin and a spring biased movable transverse pin. The movable pin may be retracted within the body of the bolt under the action of a key inserted into the lock. The protrusion mechanism comprises a shaft inside the bolt a portion of which is conical. A conical member is likewise attached to the spring biased transverse pin cooperating with the conical member of the shaft thereby allowing the external end of the transverse pin to be moved flush with the external surface of the bolt or to extend transversely therefrom. When the movable pin extends transversely from the bolt, the bolt is retained between key plates in the lock. When the movable pin is retracted, the bolt may be moved longitudinally along its axis through the key plates to unlock the lock.