Radial loadsSuper-precision cylindrical roller bearings can accommodate heavier radial loads than samesize ball bearings. They are incapable of supporting axial loads but can accommodate a limited amount of axial displacement between their inner and outer rings because there are no flanges on either the inner or outer ring, depending on the specific design.
Axial loadsDouble direction angular contact thrust ball bearings in the BTW and BTM series are designed to support axial loads only, acting in either direction. Sets of angular contact ball bearings are also a viable solution, particularly in high-speed applications.
A combined load consists of a radial and axial load acting simultaneously (fig. 1). A very effective way to accommodate combined loads is by using bearing types that can accommodate both radial and axial loads.
Super-precision bearings with these characteristics include:
- angular contact ball bearings in the 718, 719, 70 and 72 series
- single direction angular contact thrust ball bearings in the BSA and BSD series
- double direction angular contact thrust ball bearings in the BEAS and BEAM series
- axial-radial cylindrical roller bearings in the NRT series
The ability of a bearing to accommodate an axial or radial load is determined by the contact angle α (fig. 1). A bearing with a 0° contact angle can accommodate pure radial loads only. As the contact angle increases, the axial load carrying capacity increases proportionately. When the contact angle reaches 90°, the bearing becomes a full thrust bearing, capable of accommodating only axial loads. Speed capability, however, is inversely proportional to the contact angle, meaning that as the contact angle increases, speed capability decreases.