Research conducted by The Timken Company to address a critical issue for wind turbine operators received the 2015 Wilbur Deutsch Memorial Award from the Society of Tribologists and Lubrication Engineers (STLE). Timken researchers solved customer problems in the wind energy sector and underscored the value of Timken wear-resistant bearings in helping to prevent smearing damage to turbine gearbox bearings.
Dr. Ryan Evans, manager of engineering fundamentals and physical testing at Timken, led a team of researchers in investigating the root cause of smearing damage to turbine gearbox bearings manufactured by various companies. It was known that lightly loaded high speed shaft bearings (usually cylindrical roller bearings, or CRBs) in turbine gearboxes sometimes exhibited smearing damage in bands across various surface areas. These smeared areas can be initiation points for much more severe damage over the service life of a bearing.
The specific bearing assembly dynamics that caused the smearing were not well understood, and other researchers had been unable to reproduce the damage on full-size CRBs in a laboratory. “It took us a few months and some creative test-rig settings and instrumentation to determine how to generate the smearing damage. In addition, we recognized the importance and value of measuring key bearing dynamic attributes like cage slip in real time,” Dr. Evans said. “We took it a step further and were able to model the test conditions using the Timken CAGEDYN dynamic model, which led to a proposed ‘smearing criterion’ that can be used to assess smearing risk in other bearings and dynamic situations.”
The team’s research proved that erratic load zone conditions contribute to smearing damage. “As that was the only way we could reproduce the damage in a laboratory, others outside Timken increasingly point to the same mechanism as an explanation for not only smearing, but other types of bearing damage in real wind turbines,” Dr. Evans said.
He and three other Timken researchers co-authored the award-winning paper that presented the results. They are Todd Barr, principal product development engineer, based in North Canton, Ohio; Steve Boyd, senior application specialist – product, also based in North Canton; and Luc Houpert, senior scientist – product, based in Colmar, France.