In a brake actuator device, wear of brake lining, which results in the increase of stroke of the brake actuator device consisting of piston and cylinder, is compensated by an adjuster which functions automatically when the brake is operated. The adjusting process takes place continuously and preferably at the onset of the actuation of the brake. A slip clutch turns the adjuster member which is connected by screw threads to the brake actuator piston to take up slack in the piston stroke. The slip clutch is driven by a rotary member that is in turn operated in response to actuation of the brake actuator.