How To Select Coupling


First of all, during the selection of appropriate coupling for your equipment, you should have required following details about both Driver and driven machines, and these details are.

  1. Application
  2. Requirement types of coupling if you
  3. want any specific
  4. Operating hours
  5. Motor rating or your driver equipment ratings in the form of kilowatts and RPM
  6. Check the diameter of both machine shafts where the coupling hub will be install.
  7. Select Services factor according to your type of equipment which has to coupled. Example- For the centrifugal pump to electric motor SF is 1.5.


In most cases, the purchaser shall choose which type of coupling to be used whether a flexible, gear, quill shaft are other types. Mainly selection of coupling is based on equipment loading which is consists of steady-state condition or transient condition of the torque angular, axial, or parallel misalignment, axial displacement, and speed.

But there two methods of selecting appropriate coupling for your application.


  1. Select both types of equipment and then choose the required services factor for a given table accordingly.
  2. Find out required the KW/100 RPM for equipment by using the given formula.
KW/100 rpm = [Motor power (KW)*100*services factor] / Required coupling RPM
  1. From Rating selection tables, find an appropriate rating equal to or greater than the kW/100 RPM list down coupling size from the left-hand column.
  2. check your system maximum RPM.
  3. Check maximum bore capacity appropriate with your system. If the maximum bore is exceeded move to a larger size coupling with the adequate bore, but be sure the maximum RPM of coupling is not exceeded.


  1. Select services factor according to application
  2. Find out the Torque (N-M) of your system with the help of the below-mentioned formulas.
Torque (N-M)= [Motor power (KW)*9550*services factor] / Required coupling RPM
  1. From equipment Rating Tables, find a rating equal to or greater than the Calculated torque. Note coupling size from the column.
  2. Check max RPM and bore capability, if bore size increase choose coupling size accordingly but one factor always need in mind max RPM should be increased.

Lovejoy Disc Coupling Application Service Factors

Reason for wrong coupling selection

There are five common mistakes that happen during coupling selection for your application.

  1. Checking the maximum bore size for the application. in some cases, both equipment shaft sizes exceed the maximum bore size of the coupling.
  2. Fail to identify heat and chemical compatibility due to this coupling reduced.
  3. Consider installation space required is in the main factor apart appropriate selection.
  4. A common selection for many overrating applications.
  5. Cost-cutting is the main factor considered.

Term use for coupling selection

Service factors

For your equipment operating condition torque fluctuates cyclically then service factors play an important factor during selection. But couplings should be selected with the maximum torque that occurs will happen in one cycle. so services factor of coupling manufacturers uses to establish a ratio between the maximum and average torque. for your entire system and the ratio is called a service factor.

  1. What is coupling, types, and its application – Parts 1 ๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆ
  2. Flexible coupling and typesย ย ย ย ย ย ย ย ย ย  ย  ย  -Parts 2 ๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆ
  3. Rigid coupling and its typesย ย ย ย ย ย ย ย ย ย ย ย ย ย  -Parts 3ย  ๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆ
  4. Fluid coupling, types, and benefits ย  – Parts 4 ๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆ
  5. Grid coupling and advantages ย  ย  ย  – Parts 5 ย  ๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆ
  6. Gear coupling and uses ย  ย  ย  ย  ย  ย  ย  ย  ย  – Parts 6ย  ๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆ


Leave a Reply

Your email address will not be published.