The Internal Clearance of the Bearing

In order to freely rotate, a ball bearing must have a certain amount of internal freedom of movement (internal clearance, or the space between the raceway and ball). Without this internal clearance, the bearing can be difficult to rotate or may even freeze-up and be impossible to rotate. On the other hand, too much internal clearance will result in an unstable bearing that may generate excessive noise or allow the shaft to wobble. It is therefore imperative that the bearing be manufactured with the proper amount of measured internal clearance to meet the needs of the application. Loads are applied to the bearing both from the axial and radial directions; likewise, the internal clearance is measured in terms of the direction of the load (radial internal clearance and axial internal clearance). When manufactured and not yet shaft mounted, the bearing is measured in terms of its unmounted internal clearance.

Measuring Radial Internal Clearance