Ball Joints

A flexible joint using a ball and socket type of construction, used in steering linkage setups, steering knuckle pivot supports, etc. Their flexibility helps to compensate for the changes in the wheel and steering when turning or hitting a bump on the road. There are usually upper and lower ball joints attached to the upper and lower A-arms. Some have a grease nipple to allow periodic lubrication.


A protective liner or sleeve that cushions noise, friction, or movement. Suspension bushings are often made from two concentric pipes with a sleeve of rubber in the dividing space.

Idler Arms

In a parallel relay-type Steering linkage, it is one of the connecting levers. The steering Gearbox is attached to a Pitman arm which converts rotary motion to lateral motion. The pitman arm connects to a transverse centerlink which connects to the idler arm attached to the Frame side rail on the opposite side of the vehicle. The ends of the centerlink connect to two adjustable Tie rods that transmit the lateral movement of the centerlink to the steering arms at each steering knuckle.

Pitman Arms

A short lever arm splined to the steering gear cross shaft, the pitman arm transmits the steering force from the cross shaft to the steering linkage system. In this way rotary motion of the steering wheel is turned to lateral movement of the arm. Also called a drop arm.

Power Steering Pumps

A pump which supplies hydraulic pressure to reduce steering effort. The pump is usually a belt drive vane style pump. A fluid reservoir may or may not be present, the pump itself using either specialized power steering fluid or automatic transmission fluid.

Steering Racks

The device by which the movement of the steering wheel is transferred to the front wheels of an automobile. They are the metal component in a rack and pinion steering unit upon which gears silde back and forth, determining how far a corresponding wheel turns.

Suspension Links

Any arm which links the chassis to the axle

Track Rod Ends

One of the transverse bars connecting the steering system to the steering arms; the link between the pitman arm and the steering-knuckle arm.