Type-Needle Roller Bearings
Type NA, RNA
LYC’s standard needle roller bearings are NA type, which has flange or spring lock ring at the two sides of outer ring, and a flangeless inner ring. There are two structures including single row and double rows. Either the single or double-row bearings can be produced into type NA with inner ring, or type RNA without inner ring.
For larger sizes, there are circularity lubrication grooves and holes on outer ring. Outer assembly of type NA's (outer ring, needle rollers and cage) are non-separated, but inner ring can be parted from outer assembly.
When needle rollers bearings are without an inner ring, its rollers would have direct contact with shaft surface. In this way, the hardness and dimension of journal must reach the requirements of bearing raceway.
Type NAV, RNAV
Bearings of type NAV and RNAV are filled with rollers without a cage. These are another type derived from type NA and RNA. Their carrying capacity is larger than type NA and RNA. However the rotating speeds are lower.
Type NAO have a flangeless inner ring and outer ring, with two structures as single row and double rows. For double-row needle roller bearing, it has a lubrication groove and hole on the outer ring.
Type K is also called “needle and cage assembly” without an inner and outer ring, it has the smallest radial dimension of bearing. It works directly on shaft surface and bearing housing, so the matching shaft and bearing houses must ensure hardness and dimensional accuracy.
Similar to the type NAO, bearings of type NAOL have flangeless inner ring and outer ring.
Similar to type NA, these bearings have flanges or spring lock rings at the two sides of outer ring, but, are without a flange on inner ring.