The Hendrickson Primaax Ex heavy-duty vocational rear air suspension accommodates 52,000 lb. tandem capacity on C500, T800 and W900 models at Kenworth Truck dealers. Earlier versions in 46,000 lb. tandem and 69,000 lb. tridem configurations are also available. The suspension system features a new frame hanger and torque rod configuration, as well as structural beams that integrate the cross beam attachment points.