Failsafe means in tractor and trailer braking systems

摘要

To ensure that the braking systems of vehicles forming a vehicle train mutually coact, and that if such is not the case they trigger measures for emergency braking, the tractor braking system includes an electrically controlled emergency venting valve (51) in a supply line (53) to a coupling part (20) for the trailer, said emergency venting valve (51) being connected to a pressure transducer (50) adapted for sensing the operating pressure in a service supply line (35) to a second coupling part (36). When the pressure has failed or is too low in the supply line (35) between the vehicles, and when simultaneously there is an indication from driver's valve (11) that the vehicle brakes are in use, control unit (40) activates the emergency venting valve (51) to interrupt the pressure transfer to the trailer, which responds by applying the trailer brakes. IMAGE