What is NSK Ball Bearing Units ?

The NSK bearing unit is a combination of a radial ball bearing, seal, and a housing of high-grade cast iron or pressed steel, which comes in various shapes.NSK Ball bearing units consist of a precision wide inner ring bearing assembled into a housing made of cast iron or pressed steel. Units are prelubricated and are designed to slip fit on to the shaft. Locking method is either set screw locking, eccentric self-locking or concentric. On cast iron and pressed steel units, the outside diameter of the bearing and the inside diameter of the housing are sphered, allowing the bearing to swivel within the housing to accommodate initial alignment.The outer surface of the bearing and the internal surface of the housing are spherical, so that the unit is self-aligning.

The inside construction of the ball bearing for the unit  is such that steel balls and retainers of the same type  as in series 62 and 63 of the deep groove ball bearing are used. A duplex seal consisting of a  combination  of an oil-proof synthetic rubber seal and a slinger is provided on both sides.There are numerous bearing and housing combinations to accommodate a diversity of mounting surfaces, load requirements, shaft sizes and dimensional requirements.

Depending on the type, the following methods of fitting to the shaft are employed:

(1)The inner ring is fastened onto the shaft in two places by set screws.
(2)The inner ring has a tapered bore and is fitted to  the shaft by means of an adapter.
(3)In the eccentric locking collar system the inner ring is fastened to the shaft by means of eccentric grooves provided at the side of the inner ring and  on the collar.