What Is Clearance?
Think of it as the “internal gap” between a bearing’s rolling elements and its rings. Too much gap and the bearing wobbles and gets noisy. Too little and it overheats and seizes up. Get the clearance right, and your bearing lasts much longer.
Two Types of Clearance
- Radial Clearance: The up-down gap. This matters for ball bearings and cylindrical roller bearings.
- Axial Clearance: The side-to-side gap. This is key for thrust bearings and angular contact bearings.
With FODA’s tapered roller bearings, you can adjust the axial clearance during installation—giving you flexibility to get it just right.
International standards group clearance into classes. The most common is C0 (standard size) :
| Class | What It Means | When to Use It |
|---|---|---|
| C2 | Smaller than standard | Precision fits, like machine tool spindles |
| C0 | Standard | Normal machines, normal temperatures |
| C3 | Larger than standard | High heat or tight fits, like motors |
| C4 | Even larger | High temperature plus heavy loads |
Simple rule: Hotter running or tighter fit? Go up a size (C3 or C4).
How to Choose the Right Clearance
Keep three things in mind:
① Fit Tightness
When you press the inner ring onto a shaft or the outer ring into a housing, the clearance gets smaller. Tighter fit means you need larger clearance (like C3).
② Operating Temperature
Bearings heat up when running. Heat expands the parts, which shrinks the gap. High temperatures need larger clearance.
③ Speed and Load
High speed generates heat → larger clearance needed. Heavy load deforms the rolling elements → also needs larger clearance.
How FODA Ensures Accurate Clearance
- Precision grinding: Accurate raceways mean accurate clearance from the start
- In-process inspection: We measure while machining and adjust instantly
- Group matching: We pair parts by their actual clearance so every bearing is consistent
- Adjustable designs: For tapered bearings, we guide you to set optimal clearance during installation
FODA BEARING — Choose the right clearance, get ten times the life.
