At a glance
NU · non-locating
Two outer-ring flanges and no inner-ring flanges allow internal axial movement in both directions.
Choose for a radial support that must accommodate shaft-to-housing axial displacement.
NJ / NUP · locating
NJ adds one inner flange. NUP uses an inner integral flange and a loose flange ring to locate in both directions.
Choose NJ for one-way axial location or NUP for two-way location after verifying permissible thrust.
Key differences
Typical design distinctions. The complete designation and current product specification take precedence.
Swipe the table horizontally to see both options →
| What to compare | NU · non-locating | NJ / NUP · locating |
|---|---|---|
| Outer-ring flanges | NU: two | NJ and NUP: two |
| Inner-ring flanges | NU: none | NJ: one; NUP: one integral plus a loose ring |
| Axial location | NU: neither direction | NJ: one direction; NUP: both |
| Internal displacement | NU: both directions within allowance | NJ: one direction; NUP: restricted by locating design |
| Thrust assessment | No axial location through the rollers | Flange contact, lubrication and heat limit axial duty |
| Assembly detail | Keep designed displacement available | Retain and orient the loose flange ring correctly for NUP |
Before you choose
- A radial load rating is not the permissible axial flange load.
- NU, NJ and NUP with similar dimensions are functionally different.
- Do not omit the loose flange ring from a NUP assembly.
Check the actual model
Search a full designation, inspect its technical data, then compare candidate records. Similar names or dimensions do not guarantee interchangeability.
Filters show recorded catalogue attributes. Open each candidate to confirm its exact specification.
A few things worth clarifying
Can NJ plus an angle ring act like a locating bearing?
Some specified NJ plus HJ arrangements locate in both directions; compatibility is model-specific.
Why not always use NUP?
A support that must float for thermal growth can be over-constrained by a locating design.
Reference basis & limits
- SKF — Cylindrical roller bearings: NU, NJ and NUP designs, publication 13085
- SKF Evolution — Axial load-carrying capacity
Independent explanatory content; not a manufacturer endorsement or approval of a replacement. Verify current product data, fits, lubrication and operating conditions before applying a comparison.