The Bendix+ RE-6 relay emergency valve is used in dolly and trailer brake systems. It is a dual function valve, combining the functions of a relay valve and an emergency valve. The relay function is identical to that of a relay valve, a remotely controlled brake valve. Control pressure from the towing vehicle is routed through the trailer service line and on to the relay portion of the valve. The emergency function of the valve automatically applies full trailer reservoir air pressure to the trailer chambers when the trailer supply pressure falls below a predetermined minimum value. The RE-6 / RE-6NC relay emergency valve may be flange or reservoir mounted. Ports are clearly identified for delivery, service, emergency (supply) and reservoir lines.