Actuating device with dirt shielding

An actuating device for a motor vehicle, including a housing and a multi-part working piston movable in relation to the housing. The multi-part working piston has a main piston and an adjusting piston, which pistons are formed in a manner movable axially with respect to each other to compensate for wear. A clamping device clamps the main piston and the adjusting piston in relation to each other in order to fix an operative length of the working piston. The main piston and the adjusting piston are partial pistons of the working piston. A shielding element for protecting the actuating device from dirt is arranged on the housing and a partial piston or on a first partial piston and a second partial piston or on an adjusting piston and on the clamping device.