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SKF self-aligning bearing solution

for wind turbines

WIND ENERGY

Lower weight and manufacturing costs for manufacturers,higher load capacity and reliability for operators

Benefits

Reduced nacelle weight and totalweight on tower and foundation

Longer bearing service life

Improved turbine reliability

Lower production costs

Reduced maintenance needs

during operation

Improving the performance of windturbines has typically required designdecisions that add weight and cost to the nacelle. The SKF self-aligningbearing solution for wind turbine mainshafts gives turbine designers an

effective alternative that reduces nacelleweight and production costs while at thesame time increasing turbine reliability.

Higher load, lower weight

The SKF self-aligning bearing solutionfor wind turbine main shafts features aspherical roller bearing in the locatingposition and a CARB toroidal rollerbearing in the non-locating position.The combination offers a very high loadcarrying capacity in a smaller, lighterhousing.

Unlike a conventional bearing arrange-ment in which friction between theouter ring and housing must be over-come in order to accommodate axialmotion, the SKF solution employs aCARB toroidal roller bearing, which isable to accommodate both misalignmentand axial displacement of the shaft insidethe bearing at the same time. This caneliminate the problem of induced axialloads, improving reliability and at thesame time enabling the cross section of

the bearing to be smaller thanwhat would be possiblewith conventionalarrangements.

The result? Manufacturers can offer alighter, more compact wind turbine withgreater reliability and lower productioncost. Owners and operators benefit fromreduced tower and foundation weight,and improved reliability that translatesinto reduced maintenance and operatingcosts.

For more information about SKF products and solutions for the wind energyindustry, contact your SKF representative.

Conventionalarrangement

CARBarrangement

LocatingLocating Non-LocatingNon-Locating

A spherical roller bearing in the locatingposition and a CARB toroidal roller bearing inthe non-locating position enables greater loadcapacity in a smaller, lighter housing.

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Applying SKF Knowledge Engineering to improve wind turbine performance

Backed by more than 100 years of rotating machinery expertise and application experience rangingfrom the earliest wind turbines to the latest designs, SKF is helping manufacturers design the nextgeneration of wind turbines. Below is just one example of how SKF engineers are helping theworlds leading manufacturers improve wind turbine performance.

With a weight of more than 100 tonnes,the REpower 5M puts enormous loadson its rotor shaft. To handle these loads,the manufacturer chose SKF to install anSKF spherical roller bearing in the shaftslocating position, and a CARB toroidalroller bearing in its non-locatingposition. Developed by SKF, the toroidalgeometry in the CARB bearing enables it

to accommodate misalignment and axialmotion in the shaft at the same time,improving functional safety andreliability.

The CARB bearing in the REpower 5Mhas an inside diameter of 1 500 mmbut weighs only 2 700 kg. Theextraordinary size of the rotor unitrequired SKF to design a new inductionheater to heat the bearings and thehousings prior to assembly. SKF alsodesigned and supplied special split nutsthat facilitate assembly and disassembly.

In addition, REpower has asked SKF toprovide the SKF WindCon online remote

condition monitoring system for futureunits. Using vibration sensors mountedon a turbines main shaft bearings, drivetrain gearbox, and generator, the systemcollects, analyses, and compiles a range

of operating data that can be configuredto suit a wind farms specific require-ments. With CAN-bus interconnectivityto a number of systems typically found inmodern wind turbines, such as central-ized lubrication, blade monitoring, andgearbox oil condition systems, the SKFWindCon system can help wind farmsextend turbine maintenance intervals,manage resources more effectively, andavoid costly downtime. Various param-eters can be remotely monitored simplyand accurately at any maintenancecentre with Internet access, using SKFWebCon software.

During the development of our offshore wind turbine REpower 5M, we trusted in the bearings from SKF especiallythe CARB toroidal roller bearing with its innovative technical features. For a two-bearing solution within large andlimited stiff structures, we deemed it to be the best choice for a non-locating bearing. Therefore we decided on thecombination of a spherical roller bearing with a CARB bearing for the main shaft arrangement in our 5M. Wemaintained this design unaltered for the new turbine 6M.

Carsten EusterbarkeyDevelopment & DesignREpower Systems AG

SKF and CARB are registered trademarks of the SKF Group.

SKF Group 2013The contents of this publication a re the copyright of the publisher and may not be reproduced (even extracts) unless prior written permissionis granted. Every care has been taken to ensure the accuracy of the information contained in this pub lication but no liability can be accepted forany loss or damage whether direct, indirect or consequential arising out of the use of the information contained herein. Any cost savings andrevenue increases in this publication are based on results experienced by SKF customers and do not constitute a guarantee that any futureresults will be the same.

PUB 74/S7 10151/1 EN November 2013

Printed in Sweden on environmentally friendly paper.

Certain image(s) used under license from Shutterstock.com.

Photo source: REpower Systems AG

Improving functional safety and reliability

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