The pitman arm is a lever-arm component that connects to the steering gear, and it helps change radial movement into lateral motion. This is typically one of the main steering members that can result in poor performance.
One end of the pitman arm is attached to the steering box, which houses gears that convert the steering wheel's rotation into lateral movement. The other end connects to the track rod, which pivots on the idler arm to amplify the horizontal displacement. The track rod links to tie rods on either side of the vehicle, and they couple with the hubs to turn the wheels.