# Revolute joint

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> Source: https://en.wikipedia.org/wiki/Revolute_joint
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{{Short description|Kinematic pair which constrains bodies to pure rotation about a common axis}}
{{multiple image
 | width = 150
 | image1 = Revolute_Pin_Joint.png
 | alt1 = Revolute joint with shoulders cutaway view
 | image2 = Revolute joint.svg
 | alt2 = Revolute joint cutaway view
 | footer = Revolute joint with and without shoulders, cutaway views
}}

A '''revolute joint''' (also called '''pin joint''' or '''hinge joint''') is a one-[degree-of-freedom](/source/Degrees_of_freedom_(mechanics)) [kinematic pair](/source/kinematic_pair) used frequently in [mechanism](/source/Mechanism_(engineering))s and [machine](/source/machine)s.<ref name="norton">{{cite book|last=Norton|first=Robert L.|title=Design of Machinery|publisher=McGraw Hill Higher Education|location=Boston, MA|date=2008|edition=4th|pages=33|chapter=2|isbn=978-0-07-312158-1}}</ref>  The joint [constrains](/source/Constraint_(classical_mechanics)) the motion of two bodies to pure rotation along a common [axis](/source/Rotation_around_a_fixed_axis). The joint does not allow [translation](/source/Sliding_(motion)), or sliding [linear motion](/source/linear_motion), a constraint not shown in the diagram. Almost all assemblies of multiple moving bodies include revolute joints in their designs. Revolute joints are used in numerous applications such as door [hinge](/source/hinge)s and other uni-axial rotation devices.<ref name="uta">{{cite web |url=http://www.robotics.utexas.edu/rrg/learn_more/low_ed/joints/ |title=Joint Types |last=Robotics Research Group |publisher=University of Texas at Austin |access-date=2009-02-04 |url-status=dead |archive-url=https://web.archive.org/web/20090311072110/http://www.robotics.utexas.edu/rrg/learn_more/low_ed/joints/ |archive-date=2009-03-11}}</ref> 

A revolute joint is usually made by a [pin](/source/pin) or [knuckle joint](/source/knuckle_joint), through a rotary [bearing](/source/Bearing_(mechanical)). It enforces a cylindrical contact area, which makes it a [lower kinematic pair](/source/Kinematic_pair), also called a full joint. However, If there is any [clearance](/source/Engineering_tolerance) between the pin and hole (as there must be for motion), so-called surface contact in the pin joint actually becomes line contact.<ref>Norton, Robert L. ''Design of machinery: an introduction to the synthesis and analysis of mechanisms and machines''. Boston: McGraw-Hill Higher Education, 2004. p. 31.</ref> 

The contact between the inner and outer cylindrical surfaces is usually assumed to be [friction](/source/friction)less. But some use simplified models assume linear [viscous damping](/source/viscous_damping) in the form <math>T=B\,\omega</math>, where {{mvar|T}} is the [friction torque](/source/friction_torque), {{mvar|ω}} is the relative [angular velocity](/source/angular_velocity), and {{mvar|B}} is the friction constant. Some more complex models take [stiction](/source/stiction) and the [Stribeck effect](/source/Stribeck_curve) into consideration.<ref>{{Cite web |last=Moore |first=Jacobs |title=Bearing Friction |url=http://mechanicsmap.psu.edu/websites/6_friction/bearing_friction/bearingfriction.html |access-date=June 6, 2020 |website=Mechanics Map |archive-date=June 6, 2020 |archive-url=https://web.archive.org/web/20200606011049/http://mechanicsmap.psu.edu/websites/6_friction/bearing_friction/bearingfriction.html |url-status=dead }}</ref>
thumb|{{center|The door handle rotates an internal '''revolute joint''' to retract or release the latch bolt of the spring latch}}

==See also==
{{div col|colwidth=23em}}
* [Cylindrical joint](/source/Cylindrical_joint)
* [Kinematics](/source/Kinematics)
* [Degrees of freedom (mechanics)](/source/Degrees_of_freedom_(mechanics))
* [Kinematic pair](/source/Kinematic_pair)
* [Mechanical joint](/source/Mechanical_joint)
* [Prismatic joint](/source/Prismatic_joint)
{{div col end}}

== References ==
{{reflist}}

{{Kinematic pair}}

Category:Kinematics
Category:Rigid bodies

{{classicalmechanics-stub}}

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Adapted from the Wikipedia article [Revolute joint](https://en.wikipedia.org/wiki/Revolute_joint) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Revolute_joint?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.