Bearings for Wind Turbines
Wind turbine bearings are specified for a 20-year design life with rotating loads, oscillating duty and no easy access for maintenance. Blade, pitch, yaw and main shaft positions each have a different dominant load case, and false brinelling from idling or transported rotors is a recurring failure mode.
Typical duty
- Very long life targets with a calculated rating life well beyond the nominal L10 reference.
- Combined radial, axial and tilting-moment load, often with reversing direction.
- Oscillating motion at the pitch and yaw positions, which starves the raceway of lubricant film.
- Wide temperature range from -30 to +60 degrees C at the nacelle.
- Contamination from moisture ingress and from maintenance work on site.
Recommended types & suffixes
Type, reason and the suffix that follows from it
| Type | Why it suits the application | Suffix guidance |
|---|
| Spherical roller bearings | Main shaft and gearbox positions: high radial and axial capacity in a compact envelope. | C3 or C4 clearance, brass or pin-type cage, W33 lubrication groove and holes. |
| Slewing bearings | Blade and yaw positions, where the bearing also forms the structural connection. | Four-point or double-row designs with internal or external gear teeth. |
| Spherical plain bearings | Pitch and blade linkages, taking oscillating load with no rolling motion. | Steel-on-PTFE liners for maintenance-free duty, sealed against dust. |
| Cylindrical roller bearings | Planetary stages and some main shaft arrangements on newer designs. | Cage design and surface finish optimised for the lubrication film. |
Models for this application
From the live catalogue, 100–600 mm bore
Models are listed for reference. For a specific duty we confirm the clearance, seal and lubricant before quoting -
send the application.
Installation & maintenance notes
- Calculate for the fatigue load spectrum rather than a single nominal load: wind duty is a mix of normal and extreme cases.
- Oscillating positions need a lubricant that maintains a film without full rotation - false brinelling is the main enemy.
- Protect against moisture and salt: seals and the grease's water resistance matter as much as load rating.
- At the pitch and yaw positions, control backlash in the gear teeth as well as the bearing clearance.
- For transport and idling, apply a rotor lock or turning schedule to keep the raceways from fretting.
Common mistakes in this industry
- Specifying on bearing load rating alone while ignoring the oscillating duty and its effect on lubrication.
- Using a standard grease for low-temperature, high-load positions and finding it channelled on start-up.
- Leaving a rotor stationary outdoors for weeks, which produces false brinelling marks in the raceways.
Further reading
Frequently asked questions
Which bearing carries the main shaft of a wind turbine?
Three-point designs use a spherical roller bearing at the main shaft with the gearbox taking the rest; two-point and direct-drive designs use two bearings, which after a size limit take the form of a spherical or a tapered/cylindrical pair. The choice trades gearbox load against bearing size.
What is false brinelling and why does it matter here?
It is wear caused by micro-movement of the rolling elements against the raceway while the bearing is not turning, with lubricant squeezed out of the contact. It appears as regular, shallow depressions that later spall. Slow turning, vibration during transport and long parked periods are the causes.
How often should turbine bearings be greased?
Follow the turbine maker's interval, which is driven by temperature, position and grease life norms. Pitch and yaw bearings usually need periodic relubrication because their oscillating motion does not circulate grease through the raceway.
Sourcing for Wind energy?
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