The outer ring of an N type single row cylindrical bearing has no ribs, whereas the inner ring of the cylindrical bearing has two fixed ribs. This means that the N cylindrical bearing cannot locate the shaft, therefore the axial displacement of the shaft relative to the casing can be accommodated in both directions.
Single row cylindrical roller bearings are designed to accommodate high radial loads in combination with high speeds. Having two integral flanges on the outer ring and one on the inner ring, NJ design bearings can accommodate axial displacement in one direction. An important feature is the separable design, which ease of assembly and fitting and axial location.
NU Series are non-locating, single row Cylindrical Roller Bearings with cage. The inner ring is separable and without flanges on their side of the roller which slides in both directions and is commonly found in motors.