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Coupling

Coupling means actually shaft 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 are torque limiting couplings which can slip or disconnect when some torque limit is exceeded.

The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. By careful selection, installation and maintenance of couplings, substantial savings can be made in reduced maintenance costs and downtime.

Types of coupling:
Ø  Rigid coupling
Ø  Flexible coupling
Ø  Gear coupling
Ø  Fluid coupling
Ø  Diaphragm coupling
Ø  Torque limiting coupling etc.

      
                                            Figure: Coupling joints.

Applications:
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 those 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.
  • to transmit the cent percent power

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