An adjusting drive for adjusting the rotational position of a large rolling bearing that comprises two bearing rings that can be rotated relative to each other, having an actuator for rotating the two bearing rings relative to each other. According to the invention, the actuating drive has a ring channel cylinder, which is formed in or on one of the bearing rings of the large rolling bearing, and at least one piston, which is received in the ring channel cylinder in a movable manner and is drivingly connected to the other bearing ring of the two bearing rings.