Planetary Gear Load Sharing of Wind Turbine Drivetrains Subjected to Non-Torque Loads

Yi Guo, Jonathan Keller, William LaCava

Research output: Contribution to journalArticlepeer-review

55 Scopus Citations


An analytical formulation was developed to estimate the load-sharing and planetary loads of a three-point suspension wind turbine drivetrain considering the effects of non-torque loads, gravity and bearing clearance. A three-dimensional dynamic drivetrain model that includes mesh stiffness variation, tooth modifications and gearbox housing flexibility was also established to investigate gear tooth load distribution and non-linear tooth and bearing contact of the planetary gears. These models were validated with experimental data from the National Renewable Energy Laboratory's Gearbox Reliability Collaborative. Non-torque loads and gravity induce fundamental excitations in the rotating carrier frame, which can increase gearbox loads and disturb load sharing. Clearance in the carrier bearings reduces the bearing stiffness significantly. This increases the amount of pitching moment transmitted from the rotor to the gear meshes and disturbs the planetary load share, thereby resulting in edge loading. Edge loading increases the likelihood of tooth pitting and planet-bearing fatigue, leading to reduced gearbox life. Additionally, at low-input torque, the planet-bearing loads are often less than the minimum recommended load and thus susceptible to skidding.

Original languageAmerican English
Pages (from-to)757-768
Number of pages12
JournalWind Energy
Issue number4
StatePublished - 2015

Bibliographical note

Publisher Copyright:
Copyright © 2014 John Wiley & Sons, Ltd.

NREL Publication Number

  • NREL/JA-5000-60649


  • bearing clearance
  • load sharing
  • non-torque load
  • pitching moment
  • planetary gear
  • wind turbine


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