Slewing rings offer outstanding strength

Paul Boughton

By working closely with the steel industry, bearings and condition monitoring specialist Schaeffler has co-developed a new, high strength quenched and tempered steel specifically for wind turbine slewing rings that are subjected to extreme loads during blade and tower adjustment.

This new material allows full tempering and quenching of the steel and, as a result, provides outstanding strength properties, even with large ring cross sections. Zinc thermal spray surfaces, multi-layer painting and finished seal surfaces also provide the highest levels of reliability, bearing rating life and security against premature damage, such as fatigue of the raceways and surface corrosion. Due to the material properties and the applied surface protection, the bearings are suitable for use in ambient temperatures down to -40˚C.

Wind turbines must be correctly aligned to the wind conditions. The tower and rotor blades are adjusted in order that they make optimum use of wind conditions and are not subjected to excessive loads that could cause damage.

For wind tracking applications, Schaeffler currently develops and manufactures slewing rings with outside diameters up to 4,100mm. Due to their design, these slewing rings can transmit radial and axial forces, as well as tilting moments. The bearings are designed as single row or double row, four-point contact bearings without gear teeth or with internal and/or external gear teeth. Their reliable function is a significant prerequisite for cost-effective operation of wind turbines.

Schaeffler has introduced a new Wind Power Standard (WPOS) for its bearings for wind power applications, which fulfils the increasing demands in terms of reliability placed on wind turbines and components in the wind power sector. This new standard for products and processes means that Schaeffler ensures outstanding quality and reliability. By the beginning of 2014, all bearings for wind power applications will be included in this new wind power standard and will also be labeled with the WPOS mark.

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