revolute joint

{{Short description|Kinematic pair which constrains bodies to pure rotation about a common axis}}

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| alt1 = Revolute joint with shoulders cutaway view

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A revolute joint (also called pin joint or hinge joint) is a one-degree-of-freedom kinematic pair used frequently in mechanisms and machines.{{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}} The joint constrains the motion of two bodies to pure rotation along a common axis. The joint does not allow translation, or sliding 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 hinges, mechanisms, and other uni-axial rotation devices.{{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}}

A revolute joint is usually made by a pin or knuckle joint, through a rotary bearing. It enforces a cylindrical contact area, which makes it a lower kinematic pair, also called a full joint. However, If there is any clearance between the pin and hole (as there must be for motion), so-called surface contact in the pin joint actually becomes line contact.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.

The contact between the inner and outer cylindrical surfaces is usually assumed to be frictionless. But some use simplified models assume linear viscous damping in the form $T=B\backslash ,\backslash omega$, where {{mvar|T}} is the friction torque, {{mvar|ω}} is the relative angular velocity, and {{mvar|B}} is the friction constant. Some more complex models take stiction and the Stribeck effect into consideration.{{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}}

File:Revolute joint in door handle IMG 2258c.jpg