The invention relates to a method for operating an actuation device (20), which is used to clamp and loosen a clamping device which comprises a tie bolt which can be adjusted in an axial manner in a machine spindle (3), for actuating a clamping head (6) which co-operates with clamping claws (5). Initially, force is exerted upon the tie bolt (4) by means of an actuation device (20) which is used to clamp in an axial clamping direction, until the axial length thereof is fixed in relation to the machine spindle (3) by means of self-locking. According to the invention, after self-locking is obtained, the effect of the force in the direction of clamping of the actuation element (20) on the tie bolt is stopped and remains blocked whilst the clamping device is being used, and to release clamping, the tie bolt (4) is displaced by the actuation device (20) in the direction of release which is counter to the clamping direction. The invention relates to a device for carrying out said method.