Patent ID: 7322219
Filing Date: 2008-01-29
Classification: E05B,Y10T

Abstract:
1. A master keying method, comprising: providing a lock cylinder having a cylinder body with a longitudinal axis, and a plug assembly disposed in the cylinder body, the plug assembly having a keyway, a plug body having a plurality of protrusion features, and a carrier sub-assembly disposed adjacent the plug body, the carrier sub-assembly being moveable parallel to the longitudinal axis of the cylinder body between a first position and a retracted position, the plug assembly including a plurality of pins and a plurality of racks for engaging the pins, each rack of the plurality of racks having a locking bar-receiving groove and a protrusion receiving groove; inserting a valid master key into the keyway; rotating the valid master key to rotate the plug assembly from an original position to a first position in a first rotational direction; moving the carrier sub-assembly to a retracted position to decouple the plurality of racks from the plurality of pins and position the protrusion receiving groove of each rack over a corresponding protrusion feature on the plug body; removing the valid master key from the keyway; inserting a rack removal key in the keyway, the rack removal key having a cut that lifts the plurality of pins by a first amount; rotating the plug assembly to a second position in the first rotational direction to release the carrier sub-assembly from the retracted position to reengage the plurality of racks with the plurality of pins; removing a side plug from the cylinder body to disengage a locking bar from the locking bar-receiving groove of each rack, thereby decoupling all of the plurality of racks from each other rack; removing the rack removal key from the keyway; inserting a rack removal tool into the keyway, the rack removal tool having a cut that lifts the plurality of pins by a second amount greater than the first amount; moving the carrier sub-assembly to the retracted position to decouple the plurality of racks from the plurality of pins and position each rack above the corresponding protrusion feature on the plug body; removing the racks from access holes in the cylinder body; inserting each of a plurality of master racks through a respective access hole, each master rack of the plurality of master racks having a master locking bar-receiving groove and a master protrusion receiving groove; releasing the carrier sub-assembly from the retracted position to engage the plurality of master racks with the plurality of pins; remove the rack removal tool from the keyway; reinsert the rack removal key in the keyway; without removing the rack removal key, reinstalling the side plug back on to the cylinder body so that the locking bar engages with the master locking bar-receiving groove of each master rack of the plurality of master racks, thereby coupling all of the plurality of master racks together; rotating the plug assembly to the first position in a second rotational direction opposite to the first rotational direction; moving the carrier sub-assembly to the retracted position to decouple the plurality of master racks from the plurality of pins and position the master protrusion receiving groove of each master rack over a corresponding protrusion feature on the plug body; removing the rack removal key from the keyway; inserting a new master key in the keyway; and rotating the plug body back in the second rotational direction back to the original position to release the carrier sub-assembly from the retracted position to reengage the plurality of master racks with the plurality of pins.