Patent ID: 8621901

Claim:
In a lock system for vehicles and the like of the type having at least one entry closure, comprising: a lock housing for mounting adjacent the entry closure and including a cylindrically-shaped lock barrel with at least one tumbler groove extending axially therealong, a keeper shoulder disposed proximate an inner portion of the lock barrel, at least one full positioner shoulder, and a positioner shoulder having a channel, the tumbler groove being disposed between and separating the full positioner shoulder from the positioner shoulder having the channel; a cylindrically-shaped lock plug shaped for close reception in the lock barrel for rotation between locked and unlocked positions, and including an axially extending keyway and a plurality of radially shiftable outwardly biased tumblers comprising at least one key actuated lock tumbler, a positioner tumbler disposed adjacent an outer portion of the lock plug, and a keeper tumbler disposed adjacent to an inner portion of the lock plug for engagement with the keeper shoulder, wherein the lock plug includes a first rotary position and a second rotary position located a predetermined angle from the first rotary position, the keeper tumbler being axially aligned with the channel within the lock plug in the second rotary position; a control key having a shank portion shaped for close reception in the keyway with a plurality of bits configured to retract the lock tumbler and the keeper tumbler; a master key having a shank portion shaped for close reception in said keyway with a plurality of bits configured to retract only the lock tumbler and the positioner tumbler; and a customer key having a shank portion shaped for close reception in the keyway with a plurality of bits configured to retract only the positioner tumbler and the lock tumbler; wherein the lock barrel further comprises a partial positioner shoulder having an inner end disposed proximate the inner portion of the lock plug, an outer end disposed proximate the outer portion of the lock plug and a cutout portion rotationally aligned with the positioner tumbler when assembled with a tip and a cutout face; whereby removal of the lock plug from the lock barrel requires rotation of the lock plug from the first rotary position to the second rotary position and the presence of the control key within the keyway and wherein rotation of the lock plug from the first rotary position to the second rotary position is obtained by insertion of the control key within the keyway and rotation of the lock plug from the first rotary position to the second rotary position, wherein the positioner tumbler is rotated into the cutout portion, thereby permitting axial shifting of the lock plug out of the lock barrel for repair or replacement.