Cylinder lock with key removable core

Abstract

Disclosed is a cylinder lock with an annular housing defining a cavity that retains a lock core formed by a cylindrical plug within an annular shell having an internal longitudinally directed shell spline. The plug is retained within the annular shell in a locked position and is rotatable therein in one direction to an open position and in the opposite direction to a release position. A plurality of locking tumblers are retained by the plug and engage the shell spline to prevent rotation of the plug from its locked position unless the locking tumblers are withdrawn from the shell spline by a properly bitted key inserted into a keyway defined by the plug. Coupled to the plug is an actuator member that moves a locking member between latched and unlatched positions in response to rotation of the plug. Also retained by the plug and engaging the shell spline with the plug in its locked position is a release tumbler shaped and arranged to permit rotation of the plug to its open position but to prevent rotation to its release position. The release tumbler also can be withdrawn from the shell spline by a properly bitted key so as to allow rotation of the plug to its release position. Relative axial movement between the housing and the core is prevented by a retainer with the plug in either its locked or open position but such movement is permitted with the plug in its release position. An operator's key is bitted to withdraw the locking tumblers and thereby permit rotation of the plug to its open position but will not withdraw the release tumbler so as to facilitate movement of the plug to its release position. That latter action is accomplished only with a master key bitted to withdraw both the locking and release tumblers so as to permit rotation of the plug to its release position wherein the retainer allows axial removal of the locking core from the housing cavity.