Coupling selection for a CDWdrives coupling is quick and simple. Follow the guide below to find the proper coupling for your application, or contact us to have a CDWdrives engineer perform the selection.


Data required for Coupling Selection:

  • Application details (for service factor)
  • Horsepower and rpm of the driver
  • Shaft details of the driving and driven equipment

Selection Procedure:

  1. Determine the service factor (SF) from the application and classification lists below
  2. Calculate the maximum HP/100 rpm rating: HP/100 rpm = (HP x 100 x SF) / rpm
  3. Select the coupling which has a higher max rating
  4. Compare the maximum rpm capacity & bore requirements to the catalog limits for the coupling selected.


Driver: Water Turbine (100 HP at 1800 rpm)
Driven Equipment: Screw Compressor
Turbine Bore: 2.38″
Compressor Bore: 2.00″

Distance Between Shaft Ends: 5″


Service Factor for the Water Turbine & Screw Compressor: SF=2


HP/100 rpm = (100 HP x 100 x 2) / 1800

HP/100 rpm = 11.1


Coupling selection based on max rating: A4B

Coupling Bore Capacity: 2-7/8″

Maximum Speed for A4B is 3275 rpm unbalanced


DBSE for A4B is 5″

A4B is acceptable in this application.

Flex Couplings Service Factor