Wind turbine nacelles are challenging environments for drivetrains. Input forces (wind captured by blades) can vary ±20% in the span of just three seconds. Unstable drivetrain foundations generate misalignments and additional stress. And the moisture levels and temperatures extremes outdoors are generally worse than in factories.
To minimize maintenance, lubrication trends have shifted from mineral oils to specialty synthetics. “The lubricants tend to be well balanced, and have been widely tested in laboratory rigs and in the field,” says Jesse Dilk , an engineer with Klüber Lubrication North America, Londonderry, N.H. (klubersolutions. com). “The preference for synthetics include high wear protection, higher efficiency from lower friction, and a wide operating temperature range. Specialty synthetic lubricants typically outperform mineral-based versions under the same conditions. Synthetics are further driven by a requirement for extended lubrication intervals,” he says.
The company provides three synthetic formulations for turbine equipment: Klübersynth GEM 2, GEM 4 N, and GH 6. “GEM 2 series is rapidly biodegradable, high-performance oil formulated from a synthetic ester. There is less interest today because of higher costs and industry standards,” he says.
The GEM 4 N series meets current gear requirements and represents an oil (polyalpholefin) widely used in the industry. “It has outstanding anti-foam properties, protects against micro-pitting, and contains no additives that might lead to residue formation,” adds Dilk.
The GH 6 series is based on polyglycols. “These provide the highest thermal stability for longest oil life and the lowest friction coefficient of all the gear oil products that Klüber manufacturers for the wind energy industry. Past issues left some people in the industry with concerns regarding polyglycols and material compatibility. However, the issues have been solved with modern materials and components,” says Dilk.
Filed Under: Lubricants