Engineering Reference
Miniature & Instrument Ball Bearings
Basic Dimensions
The dimensions and reference codes used by NHBB are illustrated and defined here. These dimensions establish bearing size and other parameters that can help you choose the ball bearing best suited to your application.
Key for Ball Bearing Dimensions & Other Parameters
| Symbol | Description |
|---|---|
| d | inside diameter or bore |
| D | outside diameter (OD) |
| B | overall bearing width |
| Bi | inner ring width |
| Bo | outer ring width |
| Df | flange outer diameter |
| Bf | flange width |
| Li | inner ring land diameter |
| Lo | outer ring land diameter |
| r | maximum shaft or housing fillet radius bearing corners will clear |
| Z* | number of balls per row |
| Db* | nominal diameter of balls |
| Nmax* | maximum speed (rpm) |
| fn* | cage and lubricant factor |
*Not shown in the diagram.
Unflanged ball bearing.
Flanged ball bearing.
