RKB cylindrical roller bearings with four or six rows have low cross section, high load carrying capacity and stiffness, and are particularly used for metal rolling equipment in mills, where the equipment has been scaled down and jet loads remain high.
These bearings are only able to accommodate radial loads, therefore they are mounted together with deep groove or angular contact ball bearings or with taper roller bearings which take up the axial loads. The four-row cylindrical roller bearings are of separable design, which considerably simplifies mounting, maintenance and inspection.
RKB cylindrical roller bearings can tolerate moderate to high shaft speeds. The rollers and outer races are carefully matched to ensure the best load distribution.
Inner rings (designation L) are interchangeable with other assemblies (designation R). Moreover, RKB multi row bearings allow direct interchange with main premium competitor products.
RKB has a flexible manufacturing program of different styles (also special) and sizes for multi row bearings.
They have cylindrical bore and some sizes are also available with tapered bore as required by the application or by maintenance request.
The use of multi row cylindrical roller bearings in metal rolling mills exposes them to very heavy stresses, sometimes to impact loadings. The rings and rollers can be manufactured with very high quality case hardened carburizing alloy steels. Deep case depth and special heat treatment ensure superior size stability, fracture toughness and reliability.
Where the bearings are mounted with a loose fit on the roll neck, RKB multi row cylindrical roller bearings have C2 internal radial clearance and are supplied with a helical groove in the bore and/or lubrication grooves in the side faces of the bearing rings for the efficient lubrication of the mating parts (e.g. suffix AC).
To match the applications in the proper way, RKB produces the multi row cylindrical roller bearings in several construction designs within given geometric series.
The various designs differ basically in the number of inner and outer rings, in the number of loose or integral flanges on the outer ring, in the cage type, in the number of rollers in the cage pocket, etc.
Furthermore, on order RKB can produce the four-row cylindrical roller bearings sealed at both sides by radial rubbing seals or with wider inner ring with concentric shoulder.
The boundary dimensions of these bearings are not standardized. However most of them have bore and outside diameter corresponding to ISO 15 series 9 and series 0. They are produced with the normal precision grade for roll neck bearings, which means tolerances conform to class P6 for dimensional and running accuracy with values as per ISO 492.