Mazda CX-7 Control Arm With Ball Joint

The Control Arm is part of the automotive suspension system. It is also known as A-arm, it is basically a hinged suspension link between the chassis and the suspension upright or hub that carries the wheel. There are several parts to the control arm with ball joint, the inboard (chassis) end of a control arm is attached by a single pivot, which is typically a rubber bushing. This enables it to control the position of the outboard end in only a single degree of freedom, thereby maintaining the radial distance from the inboard mount. Most control arms form the lower link of a suspension. In few vehicles designs they are used as the upper link, usually with a lower wishbone. The additional radius rod is then attached to the upper arm.

The control arm primarily connects the wheel hub and steering knuckle to the frame of the vehicle. The Control arm bushings are crucial for driving comfort and handling. They help cushion the suspension system which allows to controls noise and vibrations, in addition it also provide a softer ride over bumps.

To be able to understand how it works, we need to first know how the control arm is connected to the vehicle. On one end the control arm is connected to the steering knuckle (to which the wheel is attached by way of the hub and bearing assembly) by a ball and socket called a ball joint. The other end of it is attached to the vehicle frame/body. So whenever the vehicle goes over a bump, the control arm pivots up and down with the wheel and allows the vehicle body to remain stable. The control arm also has a bushing (or a pair of bushings) on the frame/body side which allows it to pivot smoothly.

The control arm connects the wheel hub and steering knuckle to the frame of the vehicle. The come equipped with bushings on the frame side of the vehicle and a ball joint on the wheel side of the vehicle, which allows for flexible and controlled movement as per the conditions of the road and steering input from the driver.