Ensure your semi truck is Ready for the Road Ahead with an adjustable axle height, with the Watson & Chalin 12V Hi Flow Lift Axle Control Valve. By controlling the flow of compressed air, this replacement component is able to set the ride height of a vehicle higher or lower off the ground to optimize performance and suspension. Constructed with an automated solenoid valve to regulate the flow of air in and out of the system. FleetPride is your First Click in Heavy Duty .