BRAKE SYSTEM FOR A VEHICLE TRAIN AND TRACTOR THEREWITH

A fluid-operated braking system () for a tractor-trailer vehicle includes a trailer control valve (), a parking brake module (), and an electronic control unit () electrically connected to the trailer control valve () and to the parking brake module (). A pressure fluid accumulator () of the braking system () is connected to a control pressure input (P) of the trailer control valve (). A redundancy circuit controls the control pressure input (P), even during a malfunction of the control unit (). The parking brake module () includes a control valve (), a redundancy valve () and a changeover valve () controlled by an electronic switch unit () with a holding function. When the control unit () malfunctions, the last error-free switching position of the control valve () or the redundancy valve is maintained until a operationally safe resting state is reached or the ignition system is switched off.