What's common today?
4-point contact ball bearings
For decades conventional 4-point contact pitch bearings have been working in hundredthousands of wind turbines. The aerodynamic forces act upon the center of pressure on the blade and result in high moment loads on the pitch bearing.These loads create deformations on the blade root, the pitch bearing and the hub.
- widening of bearing gap
- raceway edge loading
- increased wear
- reduced service life
- grease leakage
Loads transmitted in a different way
- axial load components carried by axial raceways
- radial loads carried by radial raceways
- insignificant bearing gap widening
- constant ball contact angle
- all loads resolve into axial and radial components
- radial component causes bearing gap widening
- ball contact angle moves towards raceway edge