US Patent 7574883 Lock cylinder

A lock cylinder that includes a housing defining a cylindrical cavity, and a plug disposed in the cylindrical cavity and rotatable between a locked position and an unlocked position. The plug includes a key slot and an inner pin chamber aligned with an outer pin chamber of the housing when the plug is in the locked position. An inner pin is disposed in the inner pin chamber for movement along an axis, and is engageable with the outer pin when the plug is in the locked position. The inner pin is engageable by a key inserted into the key slot, and includes an outer surface that defines a non-axial groove. An engagement member is supported by the plug and extends into the groove.