Double row cylindrical roller bearings
SKF double row cylindrical roller bearings are available in several designs with a cylindrical or tapered bore. The SKF standard assortment presented in this section includes:
NNU design bearings (fig. 1)
NN design bearings (fig. 2)
NNUP design bearings (fig. 3)
SKF basic design double row cylindrical roller bearings are available in several designs. The major design differences between the bearings are the configuration of the inner and outer ring flanges and the cage design and material. The most popular designs are:
Where double row cylindrical roller bearings are to be mounted with a loose fit on the shaft or roll neck (e.g. to allow rapid roll changes) they can be supplied with one or more additional features (fig. 1) to compensate for disadvantages of the loose fit. The helical groove in the bore and/or lubrication grooves in the side faces of the bearing rings enable effective lubrication to be provided for the sliding contact surfaces.
SKF double row cylindrical roller bearings are fitted with one or two of the cages shown in table 1.
When used at high temperatures, some lubricants can have a detrimental effect on polyamide cages. For additional information about the suitability of cages, refer to Cages.
The speed ratings in the data table indicate:
the reference speed, which enables a quick assessment of the speed capabilities from a thermal frame of reference
the limiting speed, which is a mechanical limit that should not be exceeded unless the bearing design and the application are adapted for higher speeds