Ball joint
4069796
218234505
2008-06-09T19:33:37Z
Faradayplank
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Reverted edits by [[Special:Contributions/70.104.126.81|70.104.126.81]] to last version by Bongwarrior (using [[WP:HG|Huggle]])
{{otheruses4|automobile joints|the anatomical structure|ball and socket joint}}
In an [[automobile]], '''ball joints''' are [[spherical bearing]]s that connect the [[control arm]]s to the [[steering knuckle]]s. More specifically, a ball joint is a [[steel]] bearing stud and socket enclosed in a steel casing. 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. 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 spring|gas springs]].
==Purpose==
Ball joints are the pivot between the wheels and the [[Suspension (vehicle)|suspension]] of an automobile. Ball joints play a critical role in the safe operation of an automobile's [[steering]] and suspension. 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. 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]]. 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)
[[Category:Bearings]]
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