The flexible coupling is to transmit torque from one piece of rotating equipment to another, while accepting at the same time a small amount of misalignment. Flexible coupling misalignment is expressed, as an order of magnitude, in thousandths of an inch. Actual misalignment, expressed in coupling terms, is angular in nature and expressed in angular units, that is, degrees. How much misalignment is a function of the coupling type and installation. An installation variable is the equipment movement due to the temperature changes taking place in the machines as they go from the non-operating state to operation. Some angular values will be used in the discussion of the various types, but, again, these are for reference only. Each application must be reviewed using the type of coupling selected and the specific design proposed by the vendor.

Choice of flexible coupling can be important. Tradition and price are the two most often used criteria, and either can result in a poor choice. For most pumps, it is desirable to use a spacer coupling. This gives more parallel misalignment  capability than a close coupling of the same type and also provides better access for maintenance.

If radial space is limited, a gear coupling may be required. This will transmit more horsepower at a given speed than any other type occupying the same space. It is, however, more sensitive to misalignment than other types and also requires lubrication. The later factor is no longer as much of a disadvantage as it once was though, because non-separating coupling greases are now available. A gear coupling can handle limited end float applications for sleeve bearing motors, but doing this correctly can get complicated.



  • Fire Lock EZ Rigid Coupling
  • Fire Lock Rigid Coupling
  • Quick Vic Rigid Coupling
  • Zero-Flex Rigid Coupling
  • Quick Vic Flexible Coupling
  • Flexible Coupling
  • Reducing Coupling
  • AGS Flexible Coupling
  • Rigid Coupling for Type 316 Stainless Steel
  • Outlet Coupling
  • High Pressure Rigid Coupling
  • Vic-Boltless Coupling and Tool
  • Plain End Installation-Ready Refuse -to-Fuse coupling for HDPE Pipe
  • Refuse-to-Fuse Coupling for HDPE-to-Steel Pipe

Leave a Reply

Your email address will not be published. Required fields are marked *