The idler arm assists the pitman arm by supporting the steering linkage as it moves in the direction controlled by the steering gear. The idler arm consists of a bracket, an arm that connects the bracket to the center link of the steering linkage,  and an internal pivot bearing.

The idler arm is used on vehicles with conventional suspension systems and parallelogram steering. This type of suspension and steering arrangement is used on virtually all  rear-wheel-drive vehicles and many light trucks.