Removable cylinder lock

Claim 1

In a rotatable cylinder lock of the type formed by an elongated cylindrical housing including an outer end and an inner end, a removable lock core adapted for removable engagement within said cylindrical housing and carrying a plurality of lock tumblers and a release tumbler along the length thereof, the lock tumblers being actuated by a bitted key for effecting the rotation of the lock core between the locked and unlocked positions thereof respectively, and the release tumbler being actuated by a release key for effecting the release and removal of the lock core from the cylindrical housing when the lock core is in the unlocked position, the improvement comprising in combination: the cylindrical housing provided with a tumbler block mounted therein and extending inwardly for a distance. a tumbler ledge formed in said cylindrical housing and extending inwardly for a distance, and extending circumferentially around a portion of the interior periphery of said cylindrical housing. said tumbler ledge forming a shoulder for providing a riding surface for the release tumbler to ride on as the care is rotated said lock core provided with a block restrictor relief section formed therein along the inner end thereof, said block restrictor relief section constructed and positioned to accommodate the positioning of said tumbler block therein when said lock core is fully positioned within said cylindrical housing, and the release tumbler positioned to be retractable into said block restrictor relief section when actuated into a release position by the release key, and into overriding relation with said shoulder formed by said tumbler ledge and in blocking relation with respect to said tumbler block to prevent removal of said lock core