The Pitman arm is a steering component in an automobile or truck. As a linkage attached to the steering box (see recirculating ball) sector shaft, it converts the angular motion of the sector shaft into the linear motion needed to steer the wheels. The arm is supported by the sector shaft and supports the drag link or center link with a ball joint. It transmits the motion it receives from the steering box into the drag (or center) link, causing it to move left or right to turn the wheels in the appropriate direction. The idler arm is attached between the opposite side of the center link from the Pitman arm and the vehicle's frame to hold the center or drag link at the proper height. A worn ball joint can cause play in the steering, and may get worse over time.
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