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Basic electric motor bearing types, loads and applications

Publication date: 
January 2006
Cyndi Nyberg Esau, Former EASA Technical Support Specialist
Type of media: 

There are two main types of load that act on the bearings of a motor - radial and axial.

  • Radial - A radial load is defined as aload that is applied perpendicular tothe shaft. An example of a radial load would be an overhung load, such as with asheave.
  • Axial - An axial load, also referred to as thrust, is a load that acts parallel to the shaft on which the bearing is mounted. Just the rotor weight of a vertically-mounted motor will cause a downward axial load on the bearing. The type and magnitude of the load will determine what type of bearing should be used in the application. If the wrong type of bearing is used, it could lead to a motor failure in a short period of time. This article will address many of the common types of bearings used in electric motors, the types of load for which they are designed, their applications, and their enclosures.