At a glance
CN / normal
The normal clearance range for the specified bearing type and size. Some catalogues call it C0 or omit the marking.
Use when the calculated fit and temperature effects leave the required operating clearance from a normal starting range.
C3
A larger initial clearance class than normal for the corresponding type and bore interval.
Consider when interference fits or a hotter inner ring reduce clearance enough to require a larger initial value.
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 | CN / normal | C3 |
|---|---|---|
| Meaning | Normal initial clearance | Initial clearance greater than normal |
| Numerical range | Depends on bearing design and bore | Depends on bearing design and bore |
| Operating result | Reduced by fits and temperature differences | Also reduced; can reach a suitable operating value |
| Accuracy | Not an ABEC or ISO precision class | Not an ABEC or ISO precision class |
| Noise and motion | Depends on actual running clearance | Too much residual clearance can be undesirable |
| Replacement | Confirm the original specification | Do not treat C3 as a universal upgrade |
Before you choose
- Use the clearance table for the correct bearing type, bore and measuring condition.
- Estimate both shaft and housing interference; consider ring temperature differences.
- C0 as a clearance notation must not be confused with the static load rating C0.
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
Is C3 a high-speed quality grade?
No. It is an internal-clearance class. Speed-related fits and temperatures may justify it in a particular arrangement.
Can a C3 bearing have normal running clearance?
Yes. Mounting and operating conditions can reduce its initial clearance to the required operating range.
Reference basis & limits
- NSK — Fits and internal clearance
- NSK — Bearing Designation Systems, March 2024
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.