How to Select Bearings for Three-Phase Asynchronous Motors
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Bearing choice affects motor noise, vibration and service life. Start with the shaft and housing dimensions, then check load, speed, temperature, lubrication and sealing. A bearing number alone is not enough when the motor runs in dust, moisture or high temperature.
Tell us the duty point, nameplate data and installation requirements. We can confirm the practical variant before you place an order.
Correct bearing selection has a direct effect on the noise, vibration, service life and reliability of a three-phase asynchronous motor. The right choice depends on motor power, speed, load direction, mounting arrangement, protection level and the driven equipment.
Start with the load and mounting arrangement
For many small and medium motors, high-quality deep-groove ball bearings are a practical choice because they handle radial load and moderate axial load while offering smooth operation. Where the drive end carries heavier radial load, such as belt or pulley transmission, a cylindrical roller bearing may be required. Large vertical motors can require an angular-contact bearing arrangement to support axial thrust.
Common bearing arrangements
Deep-groove ball bearings
These bearings are commonly used in small and medium industrial motors. They are versatile and suitable for radial loads with moderate axial loads. Sealed versions can simplify maintenance where regreasing is not required.
Cylindrical roller bearings
Cylindrical roller bearings are used when high radial capacity is needed. N and NU types permit relative axial movement between rings and can be used at a floating end in suitable motor designs. In a horizontal motor under heavy radial load, the drive end may use a cylindrical roller bearing while the non-drive end uses a deep-groove ball bearing.
Angular-contact bearings
Angular-contact bearings are intended for applications with meaningful axial load. In vertical arrangements, they are often paired with a deep-groove ball bearing to support the rotor while maintaining stable axial positioning.
Selection guide by application condition
| Typical motor duty | Typical arrangement | Key consideration |
|---|---|---|
| Small and medium motors with normal radial/axial loads | Sealed deep-groove ball bearings | Low maintenance and smooth running |
| Medium horizontal motors with heavy radial load | Drive end cylindrical roller bearing; non-drive end deep-groove ball bearing | Support belt or coupling radial force |
| Higher-speed motors | Appropriately rated deep-groove ball bearings | Check speed limit, clearance and lubrication |
| Large vertical motors with axial force | Angular-contact bearing combined with deep-groove ball bearing | Provide axial load capacity and rotor stability |
Installation and maintenance notes
- Apply mounting force only to the bearing ring being fitted; do not transmit force through rolling elements.
- Use the specified fit and installation method. Some applications require controlled heating, while others use press fitting.
- Keep grease type, fill quantity and relubrication interval consistent with the motor design.
- Investigate unusual noise, heat or vibration early to avoid secondary shaft or housing damage.
A bearing must be selected as part of the complete motor-and-driven-equipment system. Share your power, speed, mounting, transmission type and load information with us for a practical recommendation. Browse three-phase motors or contact HX Equipment on WhatsApp.
Technical FAQ
Which bearing information should I provide?
Provide the bearing designation, shaft diameter, speed, load direction, grease or oil lubrication, ambient temperature and sealing requirement.
Should I change both motor bearings at the same time?
If wear history is unclear, replacing the matched set and checking the fit, preload and alignment is usually safer. Follow the motor maker’s maintenance instructions.
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