US Patent 7434431 Keying system and method

A rekeyable lock cylinder includes a cylinder body with a longitudinal axis. A locking bar is disposed in the cylinder body for movement transverse to, and rotationally about, the longitudinal axis. A plug assembly is disposed in the cylinder body and is rotateable between a first position and a second position. The plug assembly has a lock face with a tool receiving aperture. A plurality of pins and a corresponding plurality of racks are disposed in the plug assembly. The plurality of racks is selectively engageable with the plurality of pins. A first member coupled to the plurality of racks is moveable in response to application of a force against the first member by a tool received through the tool receiving aperture. The first member is configured to simultaneously disengage all of the plurality of racks from the plurality of pins in response to the movement of the first member.