How Best to Adjust a Bearing

Editorial team|6 minutes to read

Bearings are engineered for absolute precision. Over tightening or under tightening, let alone using the wrong bearing or incorrect bearing size can result not just in damage to the bearing itself, but potentially expensive damage to the machinery. Always consult the equipment manufacturer’s handbook for the particular machinery, to ascertain the exact settings required for any bearing.

Bearing Adjustment Methods

1. Adjusting a Bearing by Hand

This is best left to people with a vast amount of experience in working with bearings. You use a nut to adjust the bearing until you feel definite resistance when the shaft or housing turns. You then adjust the amount of axial bearing play, or preload, by tightening or loosening the nut afterwards. You can calculate the rotation needed using the pitch and the required axial bearing play or preload.

2. Adjusting a Bearing with a Dial Gauge

A dial gauge gives a reading of the axial bearing play as you move the housing or shaft. You can then set the preload required by inserting calibrated washers or tightening the nut.

3. Adjusting a Bearing Using a Torque Wrench

Choose a torque wrench suited to the size of the bearing and rotate the bearing as you tighten the nut. By rotating it, you make sure that all parts move into position correctly. Measuring a bearing’s frictional resistance will reveal the bearing play. This can be calculated using a formula, but for guaranteed accuracy it is best to consult the equipment manufacturer for precise figures.        

How to Adjust a Bearing

To get the bearing clearance of single row Angular Contact Ball Bearings (which can accommodate axial loads in one direction only) and Tapered Roller Bearings (rolling element bearings that can support both axial and radial forces), unlike other radial bearings with a cylindrical bore, you need to adjust one bearing in relation to the other. The bearings are usually positioned in pairs, either in an X or O pattern, and one bearing ring should be moved axially until you achieve the clearance you need.

The measurement of this preload is dependent on the bearing structure, conditions under load and the temperature at which it will operate. Don’t forget that the clearance during operation may not be the same as at the time of installation, as the temperature may be higher or lower during operation, resulting in expansion or contraction.

There is usually no need to measure both axial and radial play of these bearing types, because the two have a fixed ratio to one another.

Bearing play is measured as the distance over which one bearing ring can move relative to the other bearing ring. When in operation, the play must be almost zero. You can measure the play level by using a Feeler Gauge. Again, your machine manual should contain all the details you require.

Finding the value of axial play is best done by starting with no play at all. Then, tighten or loosen a nut in the housing or on the shaft, or place washers between the bearing ring and its lateral support.

Which method you use to adjust bearings depends on how many bearings you will be fitting. Attaching a dial to the hub is accurate, however, in the case of tapered roller bearings, you should rotate the shaft or the housing each way several times to make sure that the rollers’ machined side face lines up against the inner ring track collar. If the contact is poor, you will end up with inaccurate measurements.

Expert Insights on Bearing Adjustment

We only gain expertise in any topic by learning, either by trial and error or through training. Always consult the manufacturer’s guide to your machine before attempting to mount a bearing or bearing adjustment. Also, read our article on 'How to Safely Mount and Dismount a Bearing with Some Important Dos and Don’ts'. You could also speak with your Kramp product specialist or find a Kramp dealer near you, they will have a good understanding of the bearings and machinery in question.

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