Coupling
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2008-07-11T11:36:04Z
Gwernol
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Reverted edits by [[Special:Contributions/78.39.194.41|78.39.194.41]] ([[User talk:78.39.194.41|talk]]) to last version by 121.246.149.38
:''This article describes a mechanical connection between two things. For other meanings, see [[Coupling (disambiguation)]].''
[[Image:Rotating coupling.gif|frame|right|Rotating coupling]]
A '''coupling''' is a device used to connect two shafts together at their ends for the purpose of transmitting power. Couplings do not normally allow disconnection of shafts during operation, however there do exist [[torque limiter| torque limiting]] couplings which can slip or disconnect when some torque limit is exceeded.
==Uses==
Shaft couplings are used in machinery for several purposes, the most common of which are the following.
* To provide for the connection of shafts of units that are manufactured separately such as a motor and generator and to provide for disconnection for repairs or alternations.
* To provide for misalignment of the shafts or to introduce mechanical flexibility.
* To reduce the transmission of shock loads from one shaft to another.
* To introduce protection against overloads.
* To alter the vibration characteristics of rotating units.
== Types of shaft couplings ==
=== Rigid coupling ===
Rigid couplings are used when precise shaft alignment is required; shaft misalignment will affect the coupling's performance as well as its life. Examples:
* Sleeve or muff coupling
* Clamp or split-muff or compression coupling
* [[Flange coupling]]
=== Flexible coupling ===
Flexible couplings are designed to transmit [[torque]] while permitting some radial and axial and angular misalignment. Flexible couplings can accommodate angular misalignment up to a few [[Degree (angle)|degrees]] and some parallel misalignment. Examples:
* Bushed pin type coupling
* [[Universal joint|Universal coupling]]
* [[Oldham coupling]]
* Bellows coupling — low backlash.
* Spider or jaw coupling — elastomeric inserts for flexibility, vibration reduction.
* [[Thompson coupling]]
* [[Compliant mechanism|Resilient coupling]]
===Torque limiting coupling===
Torque limiting couplings, or [[Torque limiter | torque limiters]], protect systems against overtorque conditions.
== Requirements of good shaft alignment / good coupling setup ==
*it should be easy to connect or disconnect the coupling.
*it should transmit the full power from one shaft to other without losses.
*it does allow some misalignment between the two adjacent shaft roation axis.
*it is the goal to minimise the remaining misalignment in running operation to maximise power transmission and to maximise machine runtime (coupling and bearing and sealings lifetime).
*it should have no projecting parts.
*it is recommeded to use manufacturer's alignment target values to set up the machine train to a defined non-zero alignment, due to the fact that later when the machine is at operation temperature the alignment condition is perfect
== Tools to measure shaft axis alignment condition ==
* it is possible to measure the alignment with dial gages or feeler gages using various mechanical setups.
* it is recommended to take care of bracket sag, parallaxe error while reading the values.
* it is very convenient to use laser shaft alignment technique to perform the alignment task within highest accuracy.
* is it required to align the machine better, the laser shaft alignment tool can help to show the required moves at the feet positions.
==See also==
*[[Clutch]]
*[[Laser shaft alignment]]
*[[Compression fitting]]
*[[Piping and plumbing fittings]]
==External links==
*[http://www.unionmillwright.com/shaft.html Shaft Coupling Glossary]
*[http://www.roymech.co.uk/Useful_Tables/Drive/Drive_Couplings.html List of coupling types]
*[http://www.alignmentsupplies.com Laser Measurement Systems for Shaft & Machine Alignment]
*[http://www.skilfabcouplings.com SkilFab Engineering www.skillfabcouplings.com - Leading Coupling Manufacturer]
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[[Category:Mechanisms]]
[[Category:Hardware (mechanical)]]
[[Category:Mechanical engineering]]
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[[ru:Муфта (механическое устройство)]]
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[[it:Frizione (meccanica)]]
[[nl:Koppeling]]
[[no:Kobling]]
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