In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles. A spherical bearing is a bearing that permits angular rotation about a central point in two orthogonal directions within a specified angular limit based on the bearing geometry In automotive suspension, a control arm (sometimes called a wishbone or A-arm) is a nearly flat and roughly triangular member (or sub-frame that More specifically, a ball joint is a steel bearing stud and socket enclosed in a steel casing. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 The bearing stud is tapered and threaded. It fits into a tapered hole in the steering knuckle. A protective encasing prevents dirt from getting into the joint assembly. Motion control ball joints tend to be retained with an internal spring, which helps to prevent vibration problems in the linkage. Vibration refers to mechanical Oscillations about an equilibrium point. Commonly found in automotive throttle linkages and throttle body set ups, these are also widely used on construction equipment and on the end of gas springs. A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction In a Fuel injection engine, the throttle body is the part of the air intake system that controls the amount of air flowing into the engine in response Engineering vehicles, known by the other terms construction Equipment, earth movers heavy equipment or just plain equipment are machines specifically designed to execute A gas spring is a type of spring that unlike a typical metal spring uses a compressed Gas, contained in a cylinder and variably compressed by a piston to exert

Purpose

Ball joints are the pivot between the wheels and the suspension of an automobile. Suspension is the term given to the system of springs, Shock absorbers and linkages that connects a Vehicle to its Wheels Suspension Ball joints play a critical role in the safe operation of an automobile's steering and suspension. Steering is the term applied to the collection of components linkages etc Ball joints can also be found in most linkage systems for motion control applications, and should not be confused with spherical rod end bearings, which are a different design.

Maintenance

Sealed ball joints do not require lubrication as they are "lubed for life" but standard ball joints must be lubed from time to time. Lubrication is the process or technique employed to reduce wear of one or both surfaces in close proximity and moving relative to each another by interposing a substance called It's best to inspect standard ball joints once a year. Generally speaking, standard ball joints will outlive sealed ones because eventually the seal will break, causing the joint to dry out and rust. Rust is a general term for a series of Iron oxides, usually red oxides formed by the reaction of Iron with Oxygen in the presence of water or air While there is no exact lifespan that can be put on a sealed ball joint, they can fail as early as 80,000 miles. Signs of a failing ball joint start with a clicking or snapping sound when the wheel is turned and eventually turns into a squeaking sound at the end of a stop, when the gas pedal is used and/or also when hitting bumps.

If a ball joint fails, the results can be dangerous as the wheel's angle will be unconstrained, causing loss of control. Because the tire will be at an unintended angle, the vehicle will come to an abrupt halt damaging the tires. Also, during failure, debris can damage other parts of the vehicle.

See also

• Rod end bearing (heim joint)