Common Types of Fan Bearings Explained

No matter what kind of centrifugal fan you have, you can be sure that it has bearings in its connection to the motor. The bearings enable movement in this heavy-duty industrial machinery. There are two configurations and three common types of fan bearings, which we will outline below.

Watch the video above to see them up close, and read on for more details about how we determine which to use on your fan and how you can contribute to long bearing life.

Where to Find Your Bearings

If your motor is connected directly to the fan wheel, the bearings are located within your motor. If your motor is not directly connected to the fan wheel, then there’s going to be a shaft housed in a set of bearings and mounted to the fan between the wheel and the motor, which can be connected to the motor by either a coupling or a v-belt drive.

Two Fan Bearing Configurations: Roller Bearing and Ball Bearing

Before we discuss the three most common types of fan bearings, we should first cover the two configurations that form the foundation of the bearings. You will either have roller bearings or ball bearings. The configuration we use on your fan depends on the load in your application. Both configurations require proper maintenance and grease on a regular schedule

Roller Bearings

If there is a heavy thrust load or concern of misalignment in your fan application, then we’ll probably use roller bearings. A heavy thrust load means that there’s a significant tug on the shaft due to the weight of the fan wheel. In this case, a type of fan bearing with long rollers provides better support at very high speeds, where ball bearings would likely be crushed.

Ball Bearings

If there is no significant thrust load or weight tugging at the shaft, then ball bearings are optimal. Designed to support a spinning shaft under minimal stress loads at very high speeds, ball bearings require more alignment than roller bearings, but they spin more easily.

Three Common Types of Fan Bearings and How We Determine Design

The type of fan bearings is designated based on a combination of bearing configuration and housing style. The housing style referred to as pillow block, can either be solid or split. There are also two-bolt and four-bolt variations.

Fan Bearing Specification

Industrial centrifugal fans are higher-speed machines with shaft diameters typically between 1” and 5” diameters. Outside of those measurements, we are rarely given a specification on bearings beyond the required L-10 life, which is the expected lifespan of the bearing. The AirPro standard is higher than average at 100,000 L-10 hours, equating to about 11+ years if the bearings are maintained properly.

Fan Bearing Design

In the drawing phase of a fan design, our application engineers check out the wheel location, bearing location in reference to the wheel, and driver connection on the other side of the shaft. They then run calculations to determine which bearings will achieve our standard goal of 100,000 L-10 hours of bearing life.

Three Most Common Types of Fan Bearings

Based on the applications we serve, the three most common types of fan bearings for industrial centrifugal fans are:

  • Split Pillow Block Four-Bolt Roller Bearings
  • Split Pillow Block or Pillow Block Two-Bolt Roller Bearings
  • Solid Pillow Block Two-Bolt Ball Bearings

No matter what type of fan bearing you have in your application, the important thing for you to know is how, when, and why to ensure regular proper maintenance. You can learn a lot more about that in this article.

Hear it from an Application Engineer

Chet White, Senior Application Engineer and Sales Manager, shows details of each of the three most common types of fan bearings in this less-than-three-minute video.

To determine the right specifications for your centrifugal fan application, reach out and connect with one of our application engineers to discuss the details of your project.

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