Combined operation of friction brakes and hydrodynamic retarder brakes for heavy motor vehicles

摘要

The invention relates to a combined operation of friction brakes and hydrodynamic retarder brakes for heavy motor vehicles and proposes that a contour valve is connected to the pressure control valve provided for actuation of the friction brakes and by means of which the filling valve of the hydrodynamic retarder brake is simultaneously actuated. On braking, a control element of the pressure control valve is influenced by the connection to the internal chamber of the hydrodynamic retarder brake with the effect that the friction brake is initially actuated with a higher actuating pressure and as the internal pressure of the hydrodynamic retarder brake increases in proportion to the braking torque, is successively operated at a pressure corresponding to the distribution ratio when the hydrodynamic retarder brake exerts full braking action. This measure ensures that, on braking, the adhesion of the vehicle wheels or tracks braked is fully utilised and a uniform braking action is obtained irrespective of the vehicle speed.