Abstract: A towing arrangement on a vehicle includes a pair of glad hands for receiving pressurized air and a plurality of double check valves connecting the glad hands to valves associated with a braking system of the vehicle. Air from a first glad hand is supplied through a first of the double check valves to a spring brake modulating relay valve associated with spring brakes of the vehicle. Air from a second glad hand is supplied through a second of the double check valves to a first release valve associated with service brakes of a front axle of the vehicle and through a third of the double check valves to a second release valve associated with service brakes of a rear axle of the vehicle.

Abstract: A truck includes a pressurized air supply system for providing air to one of a plurality of air supply connections and a selector circuit for providing selection to one of the air supply connections. The circuit includes a first inversion valve with supply from a selector valve and control from a parking brake valve, a second inversion valve with supply from the parking brake valve and delivery to a first air supply connection, a synchro valve with supply from the parking brake valve and delivery to a second air supply connection, a double check valve with supply from the first inversion valve and the synchro valve and delivery to a control line of the second inversion valve and the synchro valve, a first trailer supply connection to the delivery line of the second inversion valve, and a second trailer supply connection to the delivery line of the synchro valve.

Abstract: A truck includes a pressurized air supply system for providing air to one of a plurality of air supply connections and a selector circuit for providing selection to one of the air supply connections. The circuit includes a first inversion valve with supply from a selector valve and control from a parking brake valve, a second inversion valve with supply from the parking brake valve and delivery to a first air supply connection, a synchro valve with supply from the parking brake valve and delivery to a second air supply connection, a double check valve with supply from the first inversion valve and the synchro valve and delivery to a control line of the second inversion valve and the synchro valve, a first trailer supply connection to the delivery line of the second inversion valve, and a second trailer supply connection to the delivery line of the synchro valve.

Abstract: A towing arrangement on a vehicle includes a pair of glad hands for receiving pressurized air and a plurality of double check valves connecting the glad hands to valves associated with a braking system of the vehicle. Air from a first glad hand is supplied through a first of the double check valves to a spring brake modulating relay valve associated with spring brakes of the vehicle. Air from a second glad hand is supplied through a second of the double check valves to a first release valve associated with service brakes of a front axle of the vehicle and through a third of the double check valves to a second release valve associated with service brakes of a rear axle of the vehicle.