![]() 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 L 2 and the highest level master key being L n, 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 8×8 checkerboard array having 64 squares wherein each square represents 64 possible key bitting combinations, the checkerboard being divided into subarrangements of 4 4×4 checkerboards and the 4×4 checkerboards being divided into subarrangements of 4 2×2 checkerboards c) determining the number of change keys assigned to each master key for levels L 2 through levels L n 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 8×8 checkerboard array, each piece covering the selected number of unassigned contiguous squares, wherein the number of squares=¼, 1, 4, or 16, a 4 square selection coinciding with one of the 2×2 checkerboards and a 16 square selection coinciding with one of the 4×4 checkerboards, all groups of assigned change keys below any master key L n−1−L 2 being within the same 2×2 or 4×4 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 L n in its respective tree after all other groups are completed.Ģ. ![]() This lets the person with the master key access any lock in the group, while someone with a change key can open only his or her own lock.Having described the invention, what is claimedġ. In this lock design, the lowest pin is the same length in each lock in the group, but the master wafer varies in length. In both cases, there is a gap at the shear line and the key is able to turn. The change key might raise the pins so that the shear line is just above the top of the master wafer, while the master key might raise the pins so the shear line is at the bottom of the master wafer. When three pins are combined in a shaft, there are two ways to position the pins so they open the lock. This third pin is called a master wafer or spacer. In these locks, a few of the pin pairs are separated by a third pin. The change key will open only that specific lock, while the master key will open that lock and several others in a group. Some locks are designed to work with two different keys. The right combination of pins lines up perfectly with the notches in the key. The correct key will push each pin pair up just enough so that the point where the two pins come together lines up perfectly with the space where the cylinder and the housing come together - this point is called the shear line. ![]() The incorrect key will push the pins so that most of the top pins are still partly in the plug and partly in the housing. When you insert a key, the series of notches in the key push the pin pairs up to different levels. ![]()
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