Abstract: A cylinder lock includes elongated elliptical-shaped accommodation holes for accommodating auxiliary tumblers formed on an inner cylinder, and a set/reset member which is capable of freely sliding in the inner cylinder and which is pushed by two control members each having a respective stroke length, so that the auxiliary tumblers are interposed between upper tumblers and lower tumbler and moved aside from between the upper and lower tumblers, thereby enabling changing of keys for locking and unlocking the cylinder lock. Minutely, for the setting operation, the set/reset member is pushed into by a short stroke to cause the auxiliary tumblers to be accommodated into the accommodation holes and moved along the accommodation holes and held there. For the reset operation, the set/reset member is pushed into by along stroke to move the auxiliary tumblers to the side of the upper tumbler bores of the outer cylinder.

Abstract: A cylinder lock is provided that key-change is possible without taking out auxiliary tumblers to the outside, the number of keys subjected to the key-change can be increased correspondingly to the number of auxiliary tumblers, and also, each key can be set, limitlessly in the number of times, as not-usable/usable so that even after use of a master key, other adaptable keys are usable.

Abstract: A tumbler lock comprising housing pockets in an outer housing and plug pockets in a cylindrical plug rotatably mounted in the housing holding slidably outer and inner pins respectively, auxiliary pockets in the housing corresponding to the plug pockets at a certain rotated position circumferentially spaced from the housing pockets holding therein auxiliary pins, and change pins which may be interpositioned between the inner, outer and auxiliary pins and interchanged between the respective pockets so that the change pins may be freely shifted to reset the back to be operated by different keys.