The Bendix+ TP-3+ tractor protection valve is used in combination with the Bendix+ PP-3 trailer supply valve on pre-121 tractors, and the Bendix+ PP-7 trailer supply valve - or the Bendix+ MV-3+ dash control valve - on post-121 tractors. It contains a passage for trailer supply air and a service line shut off valve. It is normally mounted behind the cab, with the delivery line from the trailer supply valve connected into the tractor emergency port and a delivery line from the brake valve connected to the tractor service port. The trailer supply and service hoses are mounted in their respective ports in the TP-3 valve.