NU and NJ are two common single‑row cylindrical roller bearing types with different axial support characteristics.
NU Bearings
- No flanges on outer ring
- Allows axial displacement in both directions
- Ideal for shafts with thermal expansion
NJ Bearings
- Flange on both inner and outer rings
- Supports axial loads in one direction
- Better for applications needing light axial retention
Comparison Summary
| Feature | NU | NJ |
|---|---|---|
| Axial Support | No | Yes (one direction) |
| Thermal Displacement | Allowed | Restricted |
| Common Uses | Expandable shafts | Gearbox shafts |
Understanding the differences helps you select the correct bearing for load and displacement requirements.