At a glance
C3
Greater-than-normal initial clearance, often used when fits or thermal effects require extra allowance.
Choose when the predicted operating clearance is satisfactory within the C3 tolerance range.
C4
A still larger initial clearance class than C3.
Consider when the calculated clearance loss would leave C3 insufficient and the complete arrangement permits C4.
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 | C3 | C4 |
|---|---|---|
| Initial class | Greater than CN | Greater than C3 |
| Numerical amount | Type- and size-specific range | Type- and size-specific range |
| Thermal case | Allow for inner/outer ring temperature difference | Larger allowance may suit a larger calculated reduction |
| Fit case | Allow for ring expansion or compression | Tighter fits may need more initial clearance |
| Excess clearance | Can reduce loaded rolling-element participation | Risk increases if extra clearance is unnecessary |
| Accuracy class | Independent of precision grade | Independent of precision grade |
Before you choose
- Neither C3 nor C4 is a universal temperature or speed rating.
- Check minimum and maximum possible operating clearance, not only a nominal midpoint.
- Changing clearance can change vibration and load distribution even with identical boundary dimensions.
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 C4 always suitable for high temperature?
No. Ring temperatures, fits, grease, seals and dimensional stabilisation all matter.
Can C4 replace C3 without other changes?
Only when an operating-clearance calculation and the application specification support that substitution.
Reference basis & limits
- NSK — Fits and internal clearance
- NSK — Industrial Motor Bearings: clearance tables and designations
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.