Idler arms and Pitman arms are part of your steering system that link the steering box to the centre link, and then to the hub assemblies. They form a pivoting support for the steering linkage and allow the proper movement to take place when you turn the wheel. Both the Idler arm and the Pitman Arm are used on vehicles with conventional suspension systems and parallelogram steering. Rear-wheel-drive vehicles and most light trucks are the vehicles on which this suspension system and parallelogram steering are used. The Pitman arm is the main player whereas the idler arm is a pivoting support for the steering linkage.