Keying system and method

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.

2. The method of claim 1 , wherein the steps of moving the carrier sub-assembly to the retracted position comprises inserting a carrier moving tool into a hole on a face surface of said plug assembly.

3. A keying system, comprising:

a cylinder body having a longitudinal axis;

a plug assembly disposed in the cylinder body, the plug assembly having a keyway, the plug assembly including a plug body 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 second position,

the plug assembly including a plurality of pins and a plurality of racks for selectively engaging the plurality of pins, each rack of the plurality of racks having a first locking bar-receiving groove along a neutral axis and at least a second locking bar-receiving groove spaced from the neutral axis, wherein a spacing of the second locking bar-receiving groove from the neutral axis of a first rack of the plurality of racks is different from a spacing of the second locking bar-receiving groove from the neutral axis of at least one other of the plurality of racks.

4. The keying system of claim 3 , wherein the plurality of racks disengage from the plurality of pins in response to movement of the carrier sub-assembly from the first position to the second position and engage the plurality of pins in response to movement of the carrier sub-assembly from the second position to the first position.

5. The keying system of claim 3 further comprising a locking bar for engaging one of the first locking bar-receiving groove and the second locking bar-receiving groove of each of the plurality of racks.

6. The keying system of claim 5 wherein the carrier sub-assembly includes a carrier having a locking bar recess that receives the locking bar.

7. The keying system of claim 6 wherein the carrier has a plurality of rack-receiving slots, each of the plurality of rack-receiving slots receiving a respective rack of the plurality of racks.

8. The keying system of claim 3 wherein the carrier sub-assembly further includes a spring catch for retaining the carrier sub-assembly in the second position.

9. The keying system of claim 8 wherein the cylinder body includes a groove for receiving the spring catch when the carrier sub-assembly is in the second position.

10. The keying system of claim 8 wherein the spring catch moves from an engaging position, wherein the spring catch retains the carrier sub-assembly in the second position, to a disengaged position in response to rotation of the plug assembly in the cylinder body.

11. The keying system of claim 3 wherein each rack includes a plurality of pin-engaging gear teeth and each pin includes at least one gear tooth for engaging the rack between two of the plurality of pin-engaging gear teeth.

12. The keying system of claim 3 , further comprising:

a rack removal key having a first cut defining a first surface having a first lift amount for engaging the pins to lift the plurality of racks when the rack removal key is inserted into the keyway; and

a rack removal tool having a second cut defining a second surface having a second lift amount for engaging the pins to lift the plurality of racks when the rack removal tool is inserted into the keyway, wherein the second cut of the rack removal tool is higher than the first cut of the rack removal key.

13. The keying system of claim 3 , wherein the plug body includes a tool-receiving aperture for receiving a carrier sub-assembly moving tool to move the carrier sub-assembly parallel to the longitudinal axis of the cylinder body from the first position to the second position.