Double row cylindrical roller bearings
Both series are available with either a cylindrical or a 1:12 tapered bore (designation suffix K). In machine tool applications, cylindrical roller bearings with a tapered bore are preferred over bearings with a cylindrical bore, because the taper enables more accurate adjustment of clearance or preload during mounting.
NN 30 series
Bearings in the NN 30 series can provide a unique balance between load carrying capacity, rigidity and speed. They are therefore typically used as the non-tool end bearing in machine tool spindles.
NN 30 series bearings have three integral flanges on the inner ring and no flanges on the outer ring.
NNU 49 series
Bearings in the NNU 49 series, with a very low cross-sectional height, provide a higher degree of stiffness than bearings in the NN 30 series, but a somewhat lower load carrying capacity.
NNU 49 series bearings have three integral flanges on the outer ring and no flanges on the inner ring.