What's common today?

4-point contact ball bearings

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.

Potential consequences:

  • widening of bearing gap
  • raceway edge loading
  • increased wear
  • reduced service life
  • grease leakage

What's new?

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

Load transmission

Contact angle variation

Edge loading

Deformation under load (same scale)