Idler arms are used on vehicles with steering box style systems. Idler arms are normally attached directly to the center link, and they support the front steering components because they attach to the body of the vehicle. On some light-duty trucks, two idler arms are used.
Idler arms allow the steering system to pivot left to right, while keeping the body isolated from this movement. A pivot built into the arm permits sideways movement of the linkage, and an internal bearing allows for low friction movement of the joint.