The combination lock disclosed has a plurality of disc-shaped tumblers mounted side-by-side for individual relative rotation around a common axis. A cylindrical member or drum having a plurality of lugs thereon is located adjacent the outer periphery of the tumblers for movement by a dial around the axis of rotation of the tumblers and for rotation on its longitudinal axis. A ratchet rotates the drum on its longitudinal axis a portion of a revolution each time the dial is returned to a selected position. Each tumbler has a protrusion on its periphery that when engaged by a lug on the drum will cause the tumbler to be rotated with the drum as the drum is moved around the axis of rotation of the tumbler by a dial. The lugs are arranged on the drum so that in one position of the drum the dial will move all of the tumblers to a preselected relative position. An audible or visible signal indicates that the lugs are in this position. Then, as the ratchet rotates the drum after each movement of the dial the tumblers will be moved in sequence to their preselected position in accordance with the combination to open the lock and allow a lock bolt to be opened through a lock bolt operating assembly.
