A tractor-trailer braking system comprising: on the tractor: a hydraulic brake pump activated by the depression of a brake pedal, pressure transmitters responsive to the hydraulic brake pressure of the hydraulic brake pump, and a comparator receiving via electric wires signals from the pressure transmitters; on the trailer: an air tank, two compressors for pressurizing the air tank, an electric-pneumatic proportional control valve, having an inlet connected by means of a pneumatic hose to the air tank and an outlet, receiving an electric signal from the comparator via an electric wire, an EBS-control having a first inlet connected to the outlet of the electric-pneumatic proportional control valve by means of a pneumatic hose, a second and a third inlet each connected to an ABS sensor by means of electric wire, two first pneumatic outlets, and a second pneumatic outlet, two air-hydraulic actuators, each having an inlet connected to one of the first pneumatic outlets of the EBS-control by means of a pneumatic hose and having an outlet connected with hydraulic brakes of the trailer or semi-trailer via hydraulic hoses, and an air bag suspension system connected via a pneumatic hose to the second pneumatic outlet of the EBS-control. on the tractor: a hydraulic brake pump activated by the depression of a brake pedal, pressure transmitters responsive to the hydraulic brake pressure of the hydraulic brake pump, and a comparator receiving via electric wires signals from the pressure transmitters; a hydraulic brake pump activated by the depression of a brake pedal, pressure transmitters responsive to the hydraulic brake pressure of the hydraulic brake pump, and a comparator receiving via electric wires signals from the pressure transmitters; on the trailer: an air tank, two compressors for pressurizing the air tank, an electric-pneumatic proportional control valve, having an inlet connected by means of a pneumatic hose to the air tank and an outlet, receiving an electric signal from the comparator via an electric wire, an air tank, two compressors for pressurizing the air tank, an electric-pneumatic proportional control valve, having an inlet connected by means of a pneumatic hose to the air tank and an outlet, receiving an electric signal from the comparator via an electric wire, an EBS-control having a first inlet connected to the outlet of the electric-pneumatic proportional control valve by means of a pneumatic hose, a second and a third inlet each connected to an ABS sensor by means of electric wire, two first pneumatic outlets, and a second pneumatic outlet, a first inlet connected to the outlet of the electric-pneumatic proportional control valve by means of a pneumatic hose, a second and a third inlet each connected to an ABS sensor by means of electric wire, two first pneumatic outlets, and a second pneumatic outlet, two air-hydraulic actuators, each having an inlet connected to one of the first pneumatic outlets of the EBS-control by means of a pneumatic hose and having an outlet connected with hydraulic brakes of the trailer or semi-trailer via hydraulic hoses, and an air bag suspension system connected via a pneumatic hose to the second pneumatic outlet of the EBS-control.