This invention relates generally to a unitized heavy duty axle suspension and steering system for self powered chassis. The steerable suspension system embodied in this invention takes advantage of the unique location and connection of the steering gear to the Pitman arm and its location and connection by the primary drag link to the bell crank assembly below and in-between the frame rails and above the axle. The primary drag link is the same length as the suspension arms and is located in a parallel plane to them when the vehicle is moving forward in a straight line. This unique arrangement virtually eliminates the phenomenon known as bump steer and allows the wheels to turn at a high degree of steer, dramatically increasing maneuverability for long wheel base chassis. The assembly with all of the steering controls and components between the rails and above the axle allow for unitized assembly and very straightforward installation.