Lock cylinder assembly

Abstract

A lock cylinder assembly for a motor vehicle ignition switch includes a lock core rotatable in a cylindrical opening of a cyclindrical sleeve anchored in a housing. A lock bar acts between the core and the sleeve to normally lock the core against rotation and to unlock the core to permit rotation when a properly bitted key is inserted into a key slot of the core. A frangible retainer acts between the core and the sleeve to define a normal axial relation therebetween and fractures under an axial extracting force to permit axial outward movement of the core relative the sleeve. A second retainer acts between the sleeve and the core and is effective upon limited axial movement of the core permitted by fracture of the frangible retainer to block further axial movement and rotational movement of the core relative the sleeve. The core has a weakened cross section intermediate the key slot and the second retainer whereby the core is fractured and a core inner portion is retained in the housing by the second retainer while a core outer portion is removed. The sleeve has a weakened cross section located at an axial location along the lock bar to permit fracture of the sleeve by the force transmitted thereto by the lock bar during extraction of the core so that a sleeve outer portion is also removed from the housing with the core outer portion, while the sleeve inner portion and core inner portion remain in the housing.