Industrial fans and blowers commonly use both a fixed (held) and expansion (floating) bearing. The proper positioning of these units is key to maximizing bearing life and equipment uptime.
When installing bearings on a horizontal shaft, overhung style fan (Example A), the fixed bearing is typically installed closest to the drive system of the shaft, with the expansion bearing located closest to the fan wheel housing.
If the fan wheel is located between the two bearings on a horizontal shaft, the fixed bearing is commonly positioned between the fan wheel housing and the drive system of the fan.
The expansion bearing is located on the opposite side of the fan wheel housing furthest from the drive system (Example B). When placing bearings on a fan or blower, it is important to remember the positions of the fixed and expansion units as installed by the fan OEM.
When installing fixed and expansion bearings on a vertical shaft fan, it is important to note the type of shaft drive system used. For vertical shaft fans using a belt-drive system, the fixed bearing should be located closest to the fan wheel housing, and the expansion unit should be positioned closest to the drive end of the shaft (Example C).
For vertical shaft applications with a direct or coupled drive system, the fixed bearing will be positioned closest to the drive end of the shaft, and the expansion bearing will be located closest to the fan wheel housing (Example D).
When bearings are being replaced on any type of fan or blower, it is important to pay close attention to the exact positioning of the fixed and expansion bearings prior to removal.
While the above recommendations will work for 99% of all fans and blowers, in rare instances, the units may be installed in positions opposite of what is stated above. This is typically done to ensure that both bearings are properly loaded based on the specific design of the fan or blower.
If you have questions about this topic or any other bearing-related issues, call (317)273-5781 or email [email protected]. For videos and other demos, visit our YouTube channel.
Dale Stallard started with Rexnord in 1988 and has held different positions in Quality Control and Product Design and Development at multiple facilities. Dale is a Senior Application Engineer supporting Rexnord's bearing business. In his current role, he provides customers with support such as helping them select the proper bearing, onsite assistance, maintenance and installation training, and troubleshooting with any issues.