Ball and Roller Bearings

CAUTION: Never replace a ball or roller bearing without first ensuring that it is in as-new condition.

Fig. 1:

Remove all traces of lubricant from the bearing by washing it in petrol or a suitable degreaser. Maintain absolute cleanliness throughout the operations. Inspect visually for markings of any form on rolling elements, bearing tracks, outer surface of outer rings or inner surface of inner rings. Reject any bearings found to be marked, since any markings in these areas indicates the onset of wear.

Hold the inner race between the fingers and thumb of one hand, spin the outer race and check that it revolves absolutely smoothly. Rotate the outer ring with a reciprocating motion, while holding the inner ring; feel for any obstruction to rotation and reject the bearing if the action is not perfectly smooth. Lubricate the bearing generously with lubricant appropriate to the installation. Inspect the shaft and bearing housing for discoloration or other marking which may suggest that movement has taken place between the bearing and bearing seat. If markings are found, use Loctite when installing the replacement bearing.

Ensure that the shaft and housing are clean and free from burrs before fitting the bearing. If one bearing of a pair shows an imperfection, it is generally advisable to renew both bearings: an exception could be made only if the bearings had covered a low mileage and it could be established that damage was confined to the one bearing.

In the case of bearings which are lubricated with grease (e.g. hub bearings) the space between the bearings should be smeared with a recommended grade of grease, and the bearings and seal should be re-packed. When fitting the bearing to the shaft, apply force only to the inner ring of bearing (Fig. 1A). When fitting the bearing to the housing, apply force only to outer ring (Fig. 1B).

Always mark components of separable bearings (e.g taper roller bearings) when dismantling, to ensure correct reassembly. Never fit a new inner roller assembly to a used outer track.