Wayward and capricious, the wind has long been used as a metaphor for constant change. Wind turbine engineers deal with that changeability every day, along with a host of other challenging factors.

Turbines must operate in desert sandstorms and corrosive saltwater. The ambient temperature at the turbine site can be blisteringly high or numbingly frigid. And the loads on the gaskets and slewing bearings can vary as the wind changes direction and the nacelle and blades swing around.

Through all these conditions, the gaskets must maintain a tight seal to protect the bearings. Every wind turbine contains at least four slewing bearings—one for each rotor blade and a fourth for the yaw bearing (on which the nacelle rests and rotates)—and each bearing contains two gaskets (see figure 1). “In a three-megawatt turbine, there are about 75 meters of this type of gasket sealing device, every millimeter critical to performance,” says Frank Schoenberg of Freudenberg Group, a German company that develops and manufactures seals, among other technologies.

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