Type N, NU Bearings of type N have two integral flanges on inner ring and a flangeless outer ring. This type of bearings permits axial displacement in double directions of the housing relative to the shaft. The bearings of type NU have two integral flanges on outer ring and a flangeless inner ring. This type of bearings permits axial displacement in double directions of the housing relative to the shaft. Type NJ, NF Bearings of type NJ have two integral flanges one on the outer ring, and one on the inner ring. This type of bearing can carry a certain amount of axial load in a single direction. Bearings of type NF have one flange on the outer ring, and two integral flanges on the inner ring. This type of bearing can carry a certain amount of axial load in a single direction.

Minimum Load-cylindrical Roller Bearings
In order to keep bearings working in good condition, a minimum load must be imposed on bearings, particularly on bearings working at high speeds, high accelerations, or with the load direction changing frequently, because under these working conditions, inertial force of balls and cage and lubricant friction will have bad influence on the rotation of bearings, and detrimental sliding movement may be caused.