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

dinside diameter or bore
Doutside diameter (OD)
Boverall bearing width
Biinner ring width
Boouter ring width
Dfflange outer diameter
Bfflange width
Liinner ring land diameter
Loouter ring land diameter
rmaximum 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.

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Unflanged ball bearing.

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Flanged ball bearing.