Combining two such joints with control arms enables motion in all three planes, allowing the front end of an automobile to be steered and a spring and shock (damper) suspension to make the ride comfortable.Ī simple kingpin suspension requires that the upper and lower control arms (wishbones) have pivot axes that are parallel, and in strict geometric relationship to the kingpin, or the top and bottom trunnions, which connect the kingpin to the control arms, would be severely stressed and the bearings would suffer severe wear. Theory Ball joints allow a limited range of smooth movement in all directionsĪ ball joint is used for allowing free rotation in two planes at the same time while preventing translation in any direction, including rotating in those planes. The 'offset' ball joint provides means of movement in systems where thermal expansion and contraction, shock, seismic motion, and torsional motions, and forces are present.

Motion-control ball joints tend to be retained with an internal spring, which helps to prevent vibration problems in the linkage. Usually, this is a rubber-like boot that allows movement and expansion of lubricant. A protective encasing prevents dirt from getting into the joint assembly. The bearing stud is tapered and threaded, and fits into a tapered hole in the steering knuckle. Ī ball joint consists of a bearing stud and socket enclosed in a casing all these parts are made of steel. They bionically resemble the ball-and-socket joints found in most tetrapod animals. In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles, and are used on virtually every automobile made. A typical ball joint with cutaway view (right) An inner tie rod end cut open to expose the ball joint. For the anatomical structure, see Ball-and-socket joint.

Ford king pin replacement