Thrust-control device for a motor vehicle

A thrust control device for switchable from two to four wheel drive and motor vehicles having a dual-circuit brake system, comprising:

• a first set of two wheels driven on a first axle;
• a second set of two wheels driven on a second axle;
• main brake cylinder means responsive to a brake pedal for generating a braking signal;
• pressure accumulator means for generating a pressure signal for controlling the rotation of the wheels during drive-slip control operation of the individual axles of the vehicle;
• first and second brake circuit means assigned to the first and second sets of wheels respectively, for receiving a braking signal from the main brake cylinder and transmitting the braking signal to the sets of wheels during the braking of the individual axles of the vehicle, and for receiving a pressure signal from the pressure accumulator means and transmitting the pressure signal to the sets of wheels during the drive-slip control operation of the individual axles of the vehicle;
• regulating valve means assigned to each of the sets of wheels for regulating the braking signal from the brake circuit means to the wheels during braking of each of the individual axles of the vehicle, and for regulating the pressure signal from the brake circuits to the wheels during drive-slip control operation of each of the individual axles to the vehicle;
• reversing valve means for operatively connecting the regulating valve means assigned to the second set of wheels to the main brake cylinder during the braking of the second axle and to the pressure accumulator means during the drive-slip control operation of the second axle;
• stop valve means for operatively connecting the regulating valve means assigned to the first set of wheels to the main brake cylinder means during the braking of the first axle;
• control valve means for operatively connecting the regulating valve means assigned to the first set of wheels to the pressure accumulator means during drive-slip control operation of the first axle, said control valve means controlling the position of the stop valve means;
• and
• wherein, when only the second axle is directly driven, the control valve means controls the stop valve means to maintain an operative connection between the regulating valve means assigned to the first set of wheels and the main brake cylinder means and when both axles are directly driven, the control valve means maintains an operative connection between the regulating valve means assigned to the first set of wheels and the pressure accumulator means.

A thrust control device for use with a motor vehicle switchable from two to four wheel drive and having one or two driven axles respectively and having an anti-blocking system for regulating the braking pressure from a main brake cylinder during braking and a drive-slip control system driven by a pressure accumulator means for controlling the spinning of the vehicle wheels during acceleration, comprising:

• reversing valve means for connecting the wheels of a driven axle of the vehicle to the main brake cylinder during braking of the axle and to the pressure accumulator means during drive-slip control of the axle,
• a stop valve means for connecting the main brake cylinder to the wheels of the other axle of the vehicle during braking of said other axle,
• a control valve means for controlling the position of the stop valve means and for connecting the pressure accumulator means to
• a pressure modulator means which controls a separate pressure input from the main brake cylinder to the wheels of the other axle during drive-slip control of said other axle, said pressure modulator means being arranged between the control valve means and the wheels of said other axle of the vehicle.