US Patent 7458239 Combination-changeable complex lock

A combination-changeable complex lock includes a movable plate, a combination lock, and a sliding member. The combination lock is composed of two notched rotating discs, two gearwheels, and a combination-alteration control device. The combination-alteration control device is rotatable to separate the gearwheels from the notched rotating discs for allowing change of the set combination. The sliding member is controllable by the combination lock to engage or disengage the peripheral notches of notched rotating discs. When the combination lock is locked, the sliding member is disengaged from the notched rotating discs and forced against the movable plate to bias the movable plate.