US 4,616,492 AGranted

Key combination lock

OwnerJ. David Barfieldinventor

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Abstract

The combination lock is one wherein movable members of the combination mechanism are set in decoding position by a key in the form of a rotatable shaft with a head at one end serving as a handle. Rotation of the key to proper decoding position is determined by shifting an index mark on the key relative to selected units of a set of letters or numerals on the lock housing. The combination mechanism makes use of a multiple number of pairs of discs concealed in the housing which must be successively set in proper decoding position, one disc relative to the other, to release a lock operating plug. In proper decoding position a slide bar, which normally blocks rotation of the lock operating plug, is shifted by key action into openings provided in the discs and out of blocking engagement with the plug, in which position the plug is free for rotation by the key. Should the need arise to change the combination, a key of the same type is made use of to shift the position of one disc of a pair relative to the other disc of that pair so that thereafter the new combination of letters or numbers, as the case may be, must be used to release the operating plug.

Claims20

Dependent claims

A combination type locking device for operation with a key member, said device comprising a substantially cylindrical housing having a key access outer end and a lock operating inner end, a lock operating plug rotatably mounted in said housing at the inner end, a plurality of pairs of discs rotatably mounted in said housing intermediate the outer and inner ends, one disc of each pair being a combination disc and the other disc of each pair being a locking disc, said locking disc having a circumferentially disposed release slot and said combination disc having a plurality of circumferentially spaced combination slots, a longitudinally extending slide bar having a first position in rotation blocking engagement with said plug and a second position free of engagement with said plug, longitudinally spaced blockers on said slide bar having positions respectively in said combination slots when said slide bar is in said first position and having positions in said release slots when said slide bar is in said second position, said slide bar being shiftable from said first position to said second position when the release slot of each pair of discs has been rotated to decoding alignment with the respective blocker whereby to release said plug for lock operation.

Dependencies are inferred from the claim text.