NKIA combined roller bearings have no inner
ring as the shaft is used as rolling groove: the shaft is grinded
and hardened and has to have the same hardeness of needle
When is not possible to harden the shaft the use of IR inner
rings is required (see special tables).
Should the bearings stand axial loads in two directions, a
mounting of two bearings in opposition of the same series is
The outer ring of a NX bearing is provided with a groove able
to accept an elastic ring, which has the duty of stopping the
bearings in case of axial loads. Excepted “Z” type, the above
bearings can be oil or grease lubricated. Closed combined
roller bearings are prelubricated before mounting in their axial
part, whereas concerning radial part they must be lubricated,
before beginning, with compatible grease.