CONTROL APPARATUS FOR LIFT AXLE/SUSPENSION SYSTEMS OF HEAVY-DUTY VEHICLES

A control apparatus for heavy-duty vehicle lift axle/suspension systems, the control apparatus comprising a source of fluid pressure, a primary controller, and a secondary controller. The primary controller is located remote from the lift axle/suspension system. The secondary controller is located proximate to the lift axle/suspension system and the source of fluid pressure and is in fluid communication with the primary controller, the source of fluid pressure, and at least one lift bag and at least one air spring of the lift axle/suspension system. The secondary controller includes a pilot-operated poppet assembly and a discrete or integrated relay valve assembly wherein the primary controller transmits at least a pneumatic pilot signal to the secondary controller in order to selectively inflate and deflate the at least one air spring and the at least one lift bag to selectively control and maintain the extension and retraction of the lift axle/suspension system.