Function
The yaw bearing connects the nacelle and tower, enabling the yaw system to orient the nacelle to any wind direction during operation.
What it costs*
The yaw bearing cost varies significantly for different nacelle layouts.
Who supplies them
IMO, Liebherr, R&M Bearings International and thyssenkrupp.
Key facts
Bearings are typically single-row 4-point contact ball bearings made from forged rings, typically of a 42CrMo4 steel, quenched and tempered. Balls are typically material 100Cr6. Total bearing mass may be up to 15 t. Raceways are hard-turned or ground after induction hardening.
Bearings see a complex load pattern and operate with long periods of no or only occasional movement over a small proportion of a revolution. Critical to long-term performance is the provision of flat mounting surfaces (so the tower flange will be machined after welding).
Bearings incorporate gear teeth to mesh with the yaw drives.
What’s in it
- Forged rings, machined, hardened and surface finished
- Balls
- Cages / spacers
- Seals
- Grease
- Metal sprayed and/or painted finish