The invention relates to a hydrodynamic retarder with a fixed casing which can be filled with operating fluid and with a rotatable bladed rotor wheel which is connected to the input shaft and a non-rotating bladed stator wheel which can be adjusted into an eccentric position relative to the bladed rotor wheel. The invention is characterised by the following feature: the bladed stator wheel is mounted in such a way that, when the retarder is empty, it automatically tends to adopt an eccentric position relative to the bladed rotor wheel and, during the filling of the retarder, is reset automatically to a position relative to the bladed rotor wheel which ensures a high braking torque.
