Couplings are used to connect two shafts for torque transmission in varied
applications. It may be to connect two units such as a motor and a generator or it may be to form a long line shaft by connecting shafts of standard lengths say 6-8 m by couplings. Coupling may be rigid or they may provide flexibility and compensate for misalignment. They may also reduce shock loading and vibration.
However there are two main types of couplings:
(a.)Rigid couplings
(b.)Flexible couplings
Rigid couplings are used for shafts having no misalignment while the flexible couplings can absorb some amount of misalignment in the shafts to be connected.
Rigid couplings:
1.Sleeve coupling
One of the simple type of rigid coupling is a sleeve coupling which consists of a cylindrical sleeve keyed to the shafts to be connected.Normally sunk keys are used and in order to transmit the torque safely it is important to design the sleeve and the key properly. The key design is usually based on shear and bearing stresses.
2.Clamp coupling
A typical clamp coupling is shown in figure. It essentially
consists of two half cylinders which are placed over the ends of the shafts
to be coupled and are held together by through bolt.
3.Ring compression type couplings
The coupling consists of two cones which are placed on
the shafts to be coupled and a sleeve that fits over the cones. Three bolts are used to draw the cones towards each other and thus wedge them firmly between the shafts and the outer sleeve.
4.Flange coupling
It is a very widely used rigid coupling and consists of two flanges keyed to
the shafts and bolted.
Flexible coupling
As discussed earlier these couplings can accommodate some
misalignment and impact. A large variety offlexible couplings are available
commercially and principal features of only a few will be discussed here.
1.Oldham coupling
These couplings can accommodate both lateral and angular misalignment
to some extent. An Oldham coupling consists of two flanges with slots on
the faces and the flanges are keyed orscrewed to the shafts. A cylindrical piece, called the disc, has a narrow rectangular raised portion running
across each face but at right angle to each other. The disc is placed
between the flanges such that the raised portions fit into the slots in the
flanges. The disc may be made of flexible materials and this absorbs
some misalignment.
2.Universal joints
These joints are capable of handling relatively large angular misalignment
and they are widely used in agricultural machinery, machine tools and
automobiles.
3.Pin type flexible coupling
One of the most commonly used flexible coupling is a pin type flexible
flange coupling in which torque is transmitted from one flange to the other
through a flexible bush put around the bolt.These are used when excessive misalignment is not expected such as a coupling between a motor and a generator or a pump mounted on a common base plate.
applications. It may be to connect two units such as a motor and a generator or it may be to form a long line shaft by connecting shafts of standard lengths say 6-8 m by couplings. Coupling may be rigid or they may provide flexibility and compensate for misalignment. They may also reduce shock loading and vibration.
However there are two main types of couplings:
(a.)Rigid couplings
(b.)Flexible couplings
Rigid couplings are used for shafts having no misalignment while the flexible couplings can absorb some amount of misalignment in the shafts to be connected.
Rigid couplings:
1.Sleeve coupling
One of the simple type of rigid coupling is a sleeve coupling which consists of a cylindrical sleeve keyed to the shafts to be connected.Normally sunk keys are used and in order to transmit the torque safely it is important to design the sleeve and the key properly. The key design is usually based on shear and bearing stresses.
2.Clamp coupling
A typical clamp coupling is shown in figure. It essentially
consists of two half cylinders which are placed over the ends of the shafts
to be coupled and are held together by through bolt.
3.Ring compression type couplings
The coupling consists of two cones which are placed on
the shafts to be coupled and a sleeve that fits over the cones. Three bolts are used to draw the cones towards each other and thus wedge them firmly between the shafts and the outer sleeve.
4.Flange coupling
It is a very widely used rigid coupling and consists of two flanges keyed to
the shafts and bolted.
Flexible coupling
As discussed earlier these couplings can accommodate some
misalignment and impact. A large variety offlexible couplings are available
commercially and principal features of only a few will be discussed here.
1.Oldham coupling
These couplings can accommodate both lateral and angular misalignment
to some extent. An Oldham coupling consists of two flanges with slots on
the faces and the flanges are keyed orscrewed to the shafts. A cylindrical piece, called the disc, has a narrow rectangular raised portion running
across each face but at right angle to each other. The disc is placed
between the flanges such that the raised portions fit into the slots in the
flanges. The disc may be made of flexible materials and this absorbs
some misalignment.
2.Universal joints
These joints are capable of handling relatively large angular misalignment
and they are widely used in agricultural machinery, machine tools and
automobiles.
3.Pin type flexible coupling
One of the most commonly used flexible coupling is a pin type flexible
flange coupling in which torque is transmitted from one flange to the other
through a flexible bush put around the bolt.These are used when excessive misalignment is not expected such as a coupling between a motor and a generator or a pump mounted on a common base plate.
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ReplyDeleteNice write up. Would love to know Where fluid coupling fall in
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