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Industrial Analytical Instrumentation

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Precision bearings and condition monitoring

Robust spherical roller bearings
make wind energy more efficient

With the objective of increasing the reliability, availability and efficiency of wind turbines, Schaeffler has optimised its spherical roller bearings for the main rotor. The development of an asymmetrical spherical roller bearing represents yet another step towards increased robustness.

The rotor shaft bearings are of critical importance in wind turbines. The locating bearing is subject to extremely high axial loads. With this in mind, Schaeffler has optimised its tried and tested standard spherical roller bearings in order to meet the specific requirements of wind turbines. In addition, Schaeffler has developed an asymmetrical bearing design. 

Robust design for reduced wear
With regard to micro-geometry, developers have improved the surfaces in order to reduce friction and thus the application of energy and wear. In addition, they have adjusted osculation to transmit rolling element normal forces across a large surface, reducing contact pressure. The rolling elements have also been specially profiled. Adjustments in macro-geometry primarily comprise two aspects. First, the engineers have reduced the internal bearing clearance, which has improved the operating clearance. This has also reduced the rolling bearing forces and the axial sliding of the drive train. Second, they have used a firm centre rib for the locating bearings of the wind turbine rotor and increased axial rigidity, which reduced the axial displacement of the drive train. In addition, the firm centre rib helps to distribute the contact pressures along the rollers. With these two measures, it has been possible to increase the robustness of the bearings against wear, which is caused by axial displacement. As part of validation, the bearings were subjected to comprehensive testing and granted Schaeffler's "X-life" seal of approval. The necessary validation steps have been certified by Germanischer Lloyd (certificate GL-CER-002-2015).

Better load distribution with asymmetrical spherical roller bearings
The asymmetrical bearing design represents yet another major step forward. This design significantly increases the axial load carrying capacity and therefore the service life of the main bearings in wind turbines. It allows a greater contact angle on the row of rollers supporting the axial load and a flatter contact angle on the row of rollers that primarily support radial loads. This results in better load distribution, reduced contact pressures and a significant reduction of the axial sliding distance

Schaeffler in profile
Schaeffler with its product brands INA, LuK and FAG is a leading provider of rolling bearing and plain bearing solutions and of linear and direct drive technology, as well as a renowned supplier to the automotive industry of high-precision products and systems for engines, transmissions and chassis applications. The globally active group of companies generated sales of approximately 11.1 billion euros in 2012. With approximately 76,000 employees worldwide, Schaeffler is one of the largest German and European industrial companies in family ownership. With 180 locations in over 50 countries, Schaeffler has a worldwide network of manufacturing locations, research and development facilities, sales companies, engineering offices, and training centres.

For further information, e-mail: info.uk@schaeffler.com  or view website: www.schaeffler.co.uk 
Refer to page 295

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