Schaeffler is launching a new high-capacity cylindrical roller bearing for wind turbine gearboxes that offers higher load ratings and reduced friction due to a new cage design. The basic static and dynamic load ratings of the new bearings are 6 per cent higher than those of a conventional cylindrical roller bearing with solid brass cage, resulting in a 20 per cent increase in rating life.
Schaeffler's FAG high-capacity cylindrical roller bearings have a new sheet steel cage that results in a more compact design than conventional solid brass cages. This slimmer cage leaves space for at least one additional rolling element in the bearing, which increases the load rating significantly.
There are other advantages too. Due to the new cage, the high-capacity bearing has significantly lower friction than full-complement cylindrical roller bearings with maximum basic load rating. The 'self-retaining' cage also simplifies bearing mounting because the rolling elements are retained even when the ring is removed.
Today, most planetary stages of wind turbine gearboxes use full-complement cylindrical roller bearings in order to achieve the highest load rating. However, full-complement roller bearings have relatively high friction because the rolling elements are in direct contact with each other. In contrast, cylindrical roller bearings with conventional solid brass cages have significantly lower friction, but often do not achieve the required load ratings due to the smaller number of rolling elements.
Innovative cage design
Schaeffler's new FAG high-capacity cylindrical roller bearings incorporate a newly developed sheet steel cage that comprises two cage rings lying one inside the other and joined together. The crosspieces of the inner cage guide the roller elements and retain the roller elements in the bearing, even when the bearing ring is removed. This means that the bearing is much easier to mount, as no separate device is required to help prevent the roller elements from falling out.
In addition, the special geometry of the cage pockets improves lubricant flow, which reduces friction and prevents damage to the bearing.
The basic static (C) and dynamic (Co) load ratings of the high-capacity cylindrical roller bearing are 6 per cent higher than those of a conventional cylindrical roller bearing with a solid brass cage. This means that the rating life is increased by more than 20 per cent.
Schaeffler plans to commence volume production of the bearings in 2011; meanwhile, the new bearings are currently undergoing trials in various customer applications.
For more information on Schaeffler's high-capacity cylindrical roller bearings for wind turbine gearboxes, go to www.schaeffler.co.uk, telephone the marketing department on +44 (0)121 313 5870 or email .