Bearings without an inner or outer ring
SKF can supply NU design cylindrical roller bearings without an inner ring (RNU series, fig. 1) and N design bearings without an outer ring (RN series, fig. 2). These bearings are typically used in applications where hardened and ground raceways are provided on the shaft or in the housing (→ Raceways on shafts and in housings). Because RNU bearings do not have an inner ring, the shaft diameter can be larger to provide a stronger, more rigid bearing arrangement. Additionally, the possible axial displacement of the shaft relative to the housing is limited only by the width of the raceway on the shaft for RNU bearings, or in the housing for RN bearings.
Certain sizes of cylindrical roller bearings in the RNU series are listed in the product table. The inside diameter Fw of the roller complement of bearings in the RNU series, when the rollers are in contact with the outer ring raceway, lies within the limits of tolerance F6Ⓔ.