US Patent 7254971 Combination lock

A combination lock includes a lock body, a locking latch, a numerical actuation unit including a plurality of number rotors and a plurality of locking rings, and a password reset unit. The password reset unit includes a reset driver slidably extended at the lock body to couple with the locking rings, wherein when the reset driver is moved to drive the locking rings to slidably disengage with number rotors, the number rotors are free to rotate on the lock body to reset a new number-combination, such that when the reset driver is released that the locking rings are slidably returned back within the number rotors, the detachable end of the locking latch is unlocked once the number rotors are rotated at the new number-combination.