Abstract: An indicator device for signalling that the wear limit has been reached for servo-operated clutches, particularly for motor vehicles. A servo housing comprises a servo piston, which can be moved forward and backward therein for disengaging and engaging the clutch respectively, and the servo piston's rest position, i.e. the position in which it is located when the clutch is engaged, in the event of an increase in clutch wear is gradually moved towards the rear end wall of the housing. The servo housing further comprises a control valve which controls the supply of pressurized fluid to a cylinder space which is located between the servo piston and the rear end wall.