The needle roller bearing without inner ring is suitable for the parts of which the radial size is limited. Because of no inner ring, the surface of shaft journal fitted with it is acted directly as rolling surface. It is requested that the surface hardness be no less than HRC60, surface roughness, no more than 0.63μm. This kind of bearing does not limit the axial shift of shaft and housing and has high limiting rotational speed.

⊙The inner ring has no shoulder in this bearing. For this purpose, the inner ring, outer ring, complete set of needles and cage can be mounted respectively. This bearing does not limit the axial shift of shaft and outer housing. Since the cage separates the needles so as to reduce friction. It can be used for the parts with high rotational speed.