The Right Grease for Lasting Wind Turbine Performance
by Doug Lucas, Advanced Engineering Technologist
June 14, 2021
Customers come to Timken for our deep knowledge and experience, and the wind energy industry is no different—every element in a turbine design makes a difference in the overall outcome.
Consider mainshaft bearing lubrication: It’s critical for extending wind turbine life and minimizing maintenance costs, so we’ve been working for nearly 20 years to understand the differences between grease performance in these applications.
Over the years, Timken engineers have produced excellent research comparing wind turbine greases. In our latest paper, we wanted to explain why one common grease performs better than another even though—on paper—it seems the opposite should be true.
The two commonly used, popular wind greases featured in this paper include a low-viscosity grease [Grease A] and a high-viscosity grease [Grease B]. Initially, we expected Grease A would lead to shorter bearing life, since grease viscosity is proportional to film thickness, which affects the lambda ratio or separation of elements in a bearing.
What we found was that Grease A outperformed Grease B, operating with 40% of the torque and 15°C lower temperatures. In bearing life tests, Grease A resulted in more than 1.65 times higher life, compared to Grease B.
Based on our testing, we concluded that grease quantity, type, and consistency all play a role in operating torque and temperatures of wind energy mainshaft bearings. Even though Grease A calculated a lower lambda ratio and measured lower film thickness, it could still result in improved application performance, compared to the higher-viscosity grease.
About Doug Lucas
As member of Timken’s wind energy application engineering team for 15 years, Doug Lucas helped pioneer the company’s wind energy business, identifying industry challenges and working with customers to solve them. Since 2016, he has continued that legacy in the role of advanced engineering technologist, working with the International Electrotechnical Commission to develop wind turbine gearbox design standards, and providing guidance to Timken product managers and engineering teams as they advance wind energy technology.