1. Couplings

2. Definition
Couplings provide a means of linking shafts or transmitting drive from a driver unit (e.g. electric motor or gearbox) to a driven unit (e.g. a pump). As within the name, a coupling couples together in 2 halves, the source of the power in whatever form it may come in, and the driven application. There are numerous types of coupling, each type which is suited to is own application; we are now going to look into this.

3. Coupling Providing Drive

4. Industrial Coupling Application

5. Coupling Facts Take up misalignment of the shafts.
Allow for expansion of the shafts caused by heating.
Permit disengagement of the shafts at low speeds or at rest.
Slip when overload occurs to protect both driven and driver units.
Prevent overloading of the driver unit during start up.
Prevent or reduce vibrations in a shaft system.
Allow machinery or sections of shafting to be removed for maintenance.

6. Coupling Drive in Action
This animation shows a motor driving an application, connected together via a coupling.

7. Coupling Alignment

8. Coupling Types & Applications
Bellows Type
Flanged
Sleeved
Universal Joint
Pin and Bush
Rubber Tyre Type
Spider Type
Gear Type
Spring / Bibby
Chain Type

9. Bellows Coupling Is flexible coupling For angular, offset & parallel
High torsional stiffness
Suitable for drives associated with instruments
High quality or translation of motion
Service life affected by load reversal applications &
When driving loads incrementally

10. Flanged Coupling Is rigid coupling Connects 2 shafts in line
Used to transmit high loads
Employed to connect to large turbines,
power drives & other large applications
Do not tolerate misalignment
Require accurate setting up

11. Sleeved Coupling Also known as muff coupling
Fits snugly over the mating shafts
Can utilise a keyway
Secured tightly via taper pins or screws
Coupling closes as it is tightened
Used when lack of space prohibits a flange coupling

12. Sleeved Coupling
Also available in a non- Compressing figuration

13. Universal Joint Coupling
Classed as solid coupling
Comes with a flexible joint
Connects to shaft via a pin
Can fit into a keyway on each shaft end
Flexes via adjoing piece between both halves
Can transmit drive / drive of angle up to 52 degrees
Used in car drives, covered with a seal known as a ‘boot’

14. Universal Joint Coupling Parts

15. Pin and Bush Coupling Classed as a solid coupling
Comes as 2 half flanges
Usually joined to each shaft via a keyway
Each half is attached via fitted pins into hole
Can have upward of 3 driving pins
Bushes made from soft material such as rubber
When fitting, correct side has to be fitted to drive half
Come with manufacturers instructions for correct fitting

16. Rubber Tyre Coupling Also known as Fenner Coupling
Comes as 2 flanges with keyway
Flanges fit onto either side of ‘tyre’
Tyre is made from rubber
Coupling can tolerate slight misalignment
Secured together via cap headed bolts
Used when vibration or torsional load is present
Rubber can perish over time, especially in high temperatures

17. Spider / Jaw Coupling Used in lighter applications
Can reduce vibration
2 halves separated by a flexible insert
Insert is usually made from a rubber
type material
Material resistant to heat, chemicals
Insert or ‘spider’ is replaceable part

18. Gear Coupling Classed as solid coupling
Used for heavy applications such as
heavy industry drives
Do not tolerate misalignment
Require precise setting up
Requires regular lubrication

19. Gear Coupling Detail

20. Spring / Bibby Coupling
Classed as flexible coupling
2 flanged with spring at centre
Excellent for absorbing any shock loading &
reducing any vibration
May require lubrication
Requires accurate setting up and alignment
Used for cement mills, conveyors, cranes, marine auxiliaries

21. Chain Coupling 2 sprockets accommodating a duplex chain
Fitted to shaft via key drive
Minor misalignment can be tolerated
The coupling assembly is usually lubricated
Limitation with speeds used
A cover normally is fitted over chain
Disconnection of coupling halves by removing chain

22. Chain Coupling in Casing
This will guarantee keeping lubrication inside and contamination outside