Selection - Coupling Information

For information on where you can buy couplings please see the Sourcing page or the links further down this page.

The purpose of this web site is not to instruct on how to select a coupling, but rather to offer some basic information on coupling styles and the properties of those styles.

We suggest you consult an engineer for advice on any critical application.

The basic criteria for selecting a shaft coupling are as follows

• Will it transmit enough torque?
• Will it accept the amount of shaft misalignment or axial movement in the application?
• Is the material compatible with the application?
• Will it allow for the amount of vibration in the application?
• Will it physically fit into the application?

The required torque can sometimes be found in an application handbook. If no handbook is available then the calculation of required torque is best left to an engineer. Once the required torque is known, the data tables for a prospective coupling selection can be consulted to determine whether the coupling will be able to achieve the required torque transmission. At this stage of any selection process it is important to realise that you should not rely solely on the data shown in product tables, especially in any critical application. A good engineer may be able to tell whether a coupling will be suitable for the job simply by knowing the coupling material, style and size, but for any critical application we recommend testing.

Angular and Parallel misalignment and shaft axial movement needs to be factored into all coupling selections. Some couplings can accommodate very little or no misalignment whilst other styles are quite tolerant. Generally couplings with rubber or plastic inserts will allow for more misalignment than full metal couplings, although some full metal designs can be very tolerant of misalignment.

In determining the material compatibility a number of criteria need to be examined, including but not limited to...

• Is the material selected capable of withstanding the high or low temperature associated with the application?
• Are there any chemicals present that may corrode any of the materials used?
• The effects of galvanic corrosion if planning to use dissimilar materials for shaft and coupling. This is beyond the scope of this document.

If the application has a lot of vibration it may be necessary to use a coupling that incorporates rubber in the design. Full metal couplings are best suited to smooth running applications. Another consideration in vibratory applications is the locking method. You may need to consider how you are going to prevent the coupling from vibrating loose from it's attachment to the shafts.

It almost goes without saying that physical space available within the application should be taken into consideration when choosing a coupling, but it is surprising just how often this factor is overlooked.

Useful information about couplings is available in the links below and to the right of this page.

Where to purchase couplings

More information on couplings