Selecting motor bearings with static load capacity

When to choose bearings through rated load

In some cases, the bearing size should be selected by the rated static load (denoted by the code C0 for convenience of description) instead of calculating the bearing life.


● The bearing is stationary under continuous or intermittent impact load.

● Under load, the bearing only makes slow reciprocating swings or regulated movements.

● Under load, the bearing speed is very low (less than 10 revolutions per minute) and only a very short life is required. In particular, in this case, for a given equivalent load P, a very low required basic dynamic load rating C will result from the life formula, so that the selected bearing may be heavily overloaded in practice.

● In addition to the normal work load, it is also subject to heavy shock loads and the bearing is rotating.

three phase motor photo.jpg

In all of the above cases, the load that the bearing can withstand is not dependent on the fatigue of the material, but on the degree of permanent deformation caused by the load on the raceway.

The load acting on a stationary or slowly reciprocatingly oscillating bearing, and the impact load acting on the rotating bearing, may cause part of the rolling body to be flattened and form indentations on the raceway. The indentations may be irregularly distributed on the raceways, or may be evenly distributed in correspondence with the distance between the rolling elements. If the load acts on the bearing, after the bearing rotates to a certain number of turns, the deformation will be evenly distributed on the entire raceway, and the bearing will be permanently deformed. This may cause adverse effects such as vibration and noise of the bearing. It may also be possible. This can lead to an increase in the play of the bearing or affect the fit with the shaft or the bearing chamber.