Ball joint linkages are types of mechanical joints consisting of a spherical head (usually a metal or plastic stud) and a spherical cavity. The stud rotates within the housing to allow for a limited range of movement in all directions.How do ball joints work?Like the ball and socket design that allows for rotational movement of your hip joint, ball joint linkages allow for a degree of rotational movement between two equipment parts. A single ball joint linkage is used to allow free movement in two planes simultaneously. They’re useful in connections where you desire a degree of rotation in movement. A similar type of joint, the rod end, has a threaded shaft attached to a circular head with an opening.What are ball joint linkages used for?Ball joint linkages are an important suspension component found in vehicles, where they will usually be combined with another ball joint with control arms to allow movement in three planes.They are also used in numerous other applications, from robotics and toys, to other apparatus requiring mechanical linkages such as aircraft components and solar panels.