Discussion papers | Copyright
https://doi.org/10.5194/wes-2018-36
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Research articles 05 Jun 2018

Research articles | 05 Jun 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Wind Energy Science (WES).

Comparison of Planetary Bearing Load-Sharing Characteristics in Wind Turbine Gearboxes

Jonathan Keller1, Yi Guo1, Zhiwei Zhang2, and Doug Lucas3 Jonathan Keller et al.
  • 1National Renewable Energy Laboratory, Golden CO, 80401, USA
  • 2Romax Technology, Boulder CO, 80301, USA
  • 3The Timken Company, North Canton OH, 44720, USA

Abstract. In this paper, the planetary load-sharing behaviour and fatigue life of different wind turbine gearboxes when subjected to rotor moments are examined. Two planetary bearing designs are compared – one design using cylindrical roller bearings with clearance and the other design using preloaded tapered roller bearings to support both the carrier and planet gears. Each design was developed and integrated into a 750-kilowatt gearbox. In field-representative dynamometer tests, the loads on each planet bearing row were measured and compared to finite element models. A significant improvement in planetary bearing load sharing was demonstrated in the gearbox with preloaded tapered roller bearings with maximum loads 20% lower than the gearbox with cylindrical roller bearings. Bearing life was calculated with a representative duty cycle measured from field tests. The predicted fatigue life of the eight-combined planet and carrier bearings for the gearbox with preloaded tapered roller bearings is 3.5 times greater than for the gearbox with cylindrical roller bearings. The influence of other factors such as carrier and planet bearing clearance, gravity, and tangential pin position error is also investigated. The combined effect of gravity and carrier bearing clearance was primarily responsible for unequal load sharing. Reducing carrier bearing clearance significantly improved load sharing, while reducing planet clearance did not. Normal tangential pin position error did not impact load sharing due to the floating sun design of this three-planet gearbox.

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Jonathan Keller et al.
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Jonathan Keller et al.
Data sets

Gearbox reliability collaborative phase 3 gearbox 2 test report J. Keller and R. Wallen https://doi.org/10.7799/1254154

Gearbox reliability collaborative phase 3 gearbox 2 test report J. Keller and R. Wallen https://doi.org/10.7799/1337868

Jonathan Keller et al.
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Short summary
The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) and industry partners successfully demonstrated a new gearbox design using preloaded tapered roller bearings in the planetary section. The new gearbox design demonstrated improved planetary load-sharing characteristics in the presence of rotor pitch and yaw moments, resulting in a predicted gearbox lifetime that is 3.5 times greater than the previous, conventional design with cylindrical roller bearings.
The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) and industry...
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