Patent ID: 6516644
Filing Date: 2003-02-11
Classification: E05B,Y10T

Abstract:
Method of master keying a system of locks, the locks using a 6 pin cylinder, each pin having 5 bittings, the method comprising:a) providing a key system schematic, the key system schematic defining: 1) a plurality of levels of master keys, the lowest level master key being level L2 and the highest level master key being Ln, 2) a plurality of change keys, the change keys being assigned to a master key and assigned to groups, 3) a plurality of trees consisting of a master key and any lower level master keys and change keys which are operated by the master key; b) providing an 8Ã—8 checkerboard array having 64 squares wherein each square represents 64 possible key bitting combinations, the checkerboard being divided into subarrangements of 4 4Ã—4 checkerboards and the 4Ã—4 checkerboards being divided into subarrangements of 4 2Ã—2 checkerboards; c) determining the number of change keys assigned to each master key for levels L2 through levels Ln; d) starting with the group of unassigned change keys with the most levels of master keys above it, selecting a number of unassigned contiguous squares from the checkerboard representing at least the number of change keys in the selected group and placing pieces on the 8Ã—8 checkerboard array, each piece covering the selected number of unassigned contiguous squares, wherein the number of squares=Â¼, 1, 4, or 16, a 4 square selection coinciding with one of the 2Ã—2 checkerboards and a 16 square selection coinciding with one of the 4Ã—4 checkerboards, all groups of assigned change keys below any master key Lnâˆ’1âˆ’L2 being within the same 2Ã—2 or 4Ã—4 checkerboard; e) repeating step d for all groups of change keys grouped below the first master key above the first selected group of change keys; f) repeating steps d and e for all remaining unassigned change keys grouped below the highest master key in the tree for the selected group; and g) repeating steps d through f for all remaining change key groups, selecting any change key groups having only master key Ln in its respective tree after all other groups are completed.