Method and apparatus for a rekeyable master key lock

A method of rekeying a master keyable lock having a longitudinal axis comprising the steps of:

• providing a plug assembly having a keyway and being rotatable within a housing in response to insertion of either a first key having a first key bitting or a second key having a second key bitting in the keyway;
• providing a plurality of key followers disposed in the plug assembly;
• providing a first plurality of racks and a second plurality of racks disposed in the plug assembly and coupled to the plurality of key followers;
• inserting the first key;
• aligning the first plurality of racks along a common axis;
• disengaging the first plurality of racks from the plurality of key followers;
• removing the first key and inserting a third key having a third key bitting;
• and
• reengaging the first plurality of racks with the plurality of key followers, thereby rendering the first key obsolete.

A method of rekeying a rekeyable master keyable lock comprising:

• providing a lock cylinder configured to be unlocked using either a first user key or a first master key;
• providing a plurality of key followers disposed in the lock cylinder;
• providing a plurality of user racks coupled to the plurality of key followers and configured to be responsive to insertion of the first user key to form a rekeying configuration wherein the first user key can be replaced and obsolete by a second user key;
• providing a plurality of master racks coupled to the plurality of key followers and configured to be responsive to insertion of the master key to form a rekeying configuration wherein the first master key can be replaced and obsolete by a second master key;

A method of rekeying a rekeyable master keyable lock comprising the steps of:

• providing a lock cylinder configured to be unlocked using either a user key or a master key;
• providing a plurality of key followers;
• providing a first plurality of racks coupled to the plurality of key followers;
• providing a second plurality of racks coupled to the plurality of key followers;
• and
• providing a locking bar configured to engage one of the first plurality of racks and the second plurality of racks to selectively obsolete either the user key or the master key and replacing the obsolete user key or master key with a different user key or master key.

A master keyable rekeyable lock having a longitudinal axis, the lock comprising:

• a housing;
• a plug assembly disposed for rotation within the cylinder housing;
• a plurality of key followers disposed in the plug assembly;
• a first plurality of racks disposed in the plug assembly and coupled to the plurality key followers;
• a second plurality of racks disposed in the plug assembly and coupled to the plurality key followers;
• and
• a locking bar disposed in the housing and configured to selectively engage one of the first plurality of racks and the second plurality of racks.

A rekeyable master keyable lock having a longitudinal axis, the lock comprising:

• a housing;
• a plug assembly disposed for rotation within the cylinder housing;
• a plurality of key followers disposed in the plug assembly;
• a first plurality of racks disposed in the plug assembly and coupled to the plurality key followers;
• a second plurality of racks disposed in the plug assembly and coupled to the plurality key followers;
• and
• a locking bar configured to selectively engage one of the first plurality of racks and the second plurality of racks.

A lock comprising:

• a housing;
• a plug body disposed in the housing;
• a plurality of key followers disposed in the plug body;
• and
• a plurality of racks coupled to the key followers, each rack of the plurality of racks including an engagement edge for engaging one the plurality of key followers and a beveled edge opposite the engagement edge.

A rekeyable master keyable lock comprising:

• a housing;
• a plug body having a longitudinally extending keyway and being disposed for rotation in the housing;
• a plurality of key followers disposed for movement in the plug body, at least a portion of each key follower being disposed to engage a key disposed in the keyway;
• a first plurality of racks engaged with the plurality of key followers and configured to align along a common axis in response to insertion of a first valid key into the keyway;
• and
• a second plurality of racks engaged with the plurality of key followers and configured to align along a common axis in response to insertion of a second valid key into the keyway, wherein the first valid key has different bitting than the second valid key and the lock is operable using either of the first valid key and the second valid key.

A rekeyable master keyable lock comprising:

• a keyway;
• a plurality of key followers;
• a plurality of user racks coupled to the plurality of key followers and configured to unlock the lock in response to insertion of a valid user key in the keyway;
• and
• a plurality of master racks coupled to the plurality of key followers and configured to unlock the lock in response to insertion of a valid master key in the keyway, the plurality of key followers, the plurality of user racks and the plurality of master racks cooperating to allow the user key to be rekeyed independently of the master key and to allow the master key to be rekeyed independently of the user key.