Pressure control valve for trailer pneumatic brakes - isolates trailer supply when trailer brake line broken, for hold-off brake operation

摘要

The supply line to the trailer pneumatic brakes is protected by a special pressure control valve which is spring loaded and is subjected to the pressures in the two braking systems, i.e. trailer and towing unit. In the event of a leak in the trailer brakes the valve closes so that the trailer brake pressure falls more rapidly than it would if supplied from the towing unit. This enables the automatic hold-off brake to operate rapidly. To increase the brake response, the control valve element can be coupled to a venting valve which vents the line of the trailer brakes. If the trailer is not coupled to the towing unit then the valve operates in any case and is thus prevented from seizing up through non-use and corrosion.