Vehicular braking system utilizing a hydrodynamic brake and friction brake

A braking system for use in a vehicle in which a friction brake is associated with each wheel of the vehicle and a hydrodynamic brake is associated with an axle of the vehicle, said hydrodynamic brake applying a braking torque to said axle, the magnitude of said braking torque and therefore the magnitude of the deceleration of said axle varying as a function of the amount of fluid in said brake, said braking system comprising:

• reference signal generating means for generating a first signal representative of a desired magnitude of said deceleration of said axle;
• deceleration measuring means for generating a second signal representative of the actual magnitude of said deceleration of said axle, said deceleration measuring means comprising speed sensing means for generating a speed signal representative of the speed of said axle, and differentiating means for differentiating said speed signal so as to generate said second signal;
• control means responsive to said first and second signals for varying said amount of fluid in said hydrodynamic brake in such a manner that said actual magnitude of said deceleration of said axle is adjusted towards said desired magnitude of said deceleration;
• and
• a first pressure switch means for monitoring the fluid pressure in said hydrodynamic brake and for preventing any rise therein once a given pressure in said hydrodynamic brake is reached.