SKF high-capacity cylindrical roller bearings

1 SKF high - capacity cylindrical roller bearings Full complement bearings with a cage Higher load ratings and longer service life Applications like industrial gearboxes, gear- However, direct roller -to- roller contact in a boxes in wind turbines or machines for min- full complement bearing increases friction, ing equipment require components that can heat generation and the risk for wear. Con- provide high operational reliability and long sequently, the permissible speed is reduced. service life. In these applications, load carry- Under particularly difficult operating condi- ing capacity is particularly important, which tions, these disadvantages quickly add up to is the reason why full complement bearings substantially reduced bearing service life.

2 Are frequently used. To achieve the maximum load carrying Full complement bearings do not have a capacity of a full complement bearing and cage separating the rollers, which enables the robust performance of a bearing with a a maximum number of rollers. cage, SKF developed high - capacity cylindrical Therefore, the advantage of full comple- roller bearings . These bearings combine the ment bearings is that they can accommo- advantages of both bearing types. date much heavier loads than same-sized bearings with a cage. SKF high - capacity cylindrical roller bearings with an inner ring or outer ring shoulder-guided cage 2.

3 An innovative bearing design Traditionally, higher load carrying capacities below the recommended minimum radial Fig. 1. have been achieved by incorporating larger load, the sliding ratio for these bearings with rollers. However, to do this within the ISO an inner ring shoulder-guided cage is sig- standardized boundary dimensions requires nificantly lower than for conventional cylin- thinner rings. Thinner rings increase the risk drical roller bearings with a cage of the of ring creep, ring or flange cracks, and fret- same size. For bearings in the 22 dimension ting corrosion. Also, larger rollers are more series, the risk for sliding damage is even prone to smearing due to increased inertial more reduced than for 23 series bearings .

4 Forces. 22 series bearings have a lower cross sec- The new SKF high - capacity cylindrical tion and smaller rollers, which results in roller bearings ( fig. 1), which contain lower inertial forces. more rollers than EC design cylindrical roller The rollers are coated with black oxide bearings , not only maintain the original ISO to further reduce the risk of sliding damage boundary dimensions, they also maintain inside the bearing during initial start-up. the internal geometry of the EC design. The Cross section of an SKF high - capacity result: increased dynamic and static load cylindrical roller bearing carrying capacities and consequently longer A sustainable product bearing service life.

5 SKF high - capacity cylindrical roller bearings were designed to support SKF's Beyond Reduced risk of roller Zero sustainability efforts. Through this sliding initiative, SKF is committed to creating products that consume less energy when SKF high - capacity cylindrical roller bearings in use than the energy needed to manufac- are specially designed to accommodate the ture them. requirements of wind turbines and applica- From an environmental standpoint, these tions where high load carrying capacity is bearings can provide the following benefits: a prerequisite. In these applications bearings must frequently operate below the requisite lower frictional losses minimum load.

6 Under these conditions, the possibility for downsizing inertial forces of the rollers and cage, and increased bearing service life the friction in the lubricant, can have a det- rimental effect on the rolling conditions in The components of SKF high - capacity the bearing arrange ment and may cause cylindrical roller bearings are all made damaging sliding movement between the of steel, enabling easy recycling. rollers and raceways. With the inner ring shoulder-guided cage of SKF high - capacity cylindrical roller bear- ings, this risk is reduced. When operating 3. Performance advantage Optimized cage design Fig.

7 2. The key to the new SKF high - capacity cylindrical roller bearing lies in its new cage design. The design of this steel cage goes beyond the design of traditional machined brass cages. The new window-type steel cage is de- signed so that its cage bars are displaced relative to the roller pitch diameter. This does not have an unfavourable effect on the strength of the cage bars, but enables the rollers to be placed closer to each other, cre- with an inner ring shoulder-guided cage with an outer ring shoulder-guided cage ating room for additional rollers. Advanced modelling techniques have SKF high - capacity cylindrical roller bearings with been used to optimize the cage design.

8 An inner ring and outer ring shoulder-guided cage The shape of the cage bars minimizes stress concentration and enhances lubricant film formation. The low cross-sectional height of the cage promotes oil flow through the bearing and quick formation of a lubricant Optimized roller set film. The low weight of the cage reduces To minimize the risk of smearing or wear, inertial forces, which improves the sliding especially during the running-in phase, the behaviour of the cage, especially under light rollers in SKF high - capacity cylindrical roller load conditions. bearings have been coated, as standard, The cage can be either inner or outer ring with black oxide.

9 Shoulder-guided ( fig. 2). Shoulder-guided The increased number of rollers enables cages are beneficial if high speed, rapid higher static and dynamic load ratings com- acceleration or shock load occur. pared to standard cylindrical roller bearings with a cage. 4. The SKF Explorer A higher level of performance Unique heat treatment process advantage When compared to full complement cylin- drical roller bearings , SKF Explorer high - . To cope with extreme operating conditions like those in wind turbine gearboxes, SKF. In contrast to full complement cylindrical capacity cylindrical roller bearings undergo Explorer high - capacity cylindrical roller roller bearings , all SKF high - capacity cylin- a number of enhancements.

10 These enhance- bearing components undergo a customized drical roller bearings are available in the ments are designed to improve reliability heat treatment process that enhances SKF Explorer performance class. The SKF and increase the service life of the bearing , toughness and reduces the possibility of Explorer performance class is standard for even in the most demanding applications. premature bearing failure. bearings in the 23 series up to a 150 mm The superior performance of SKF Explorer bore diameter and for bearings in the 22 class bearings is mainly achieved by three Advanced surface finish series up to a 200 mm bore diameter.