Temperature difference between the inner and outer ring

Specification of the temperature difference between the inner and outer ring of the bearing during operation.

The temperature of the inner ring of a bearing at operating temperature is normally slightly higher than the temperature of the outer ring if the shaft is not cooled or the housing is not heated. This is due to the fact that the heat dissipation of the outer ring with its larger surface is more intensive than that of the inner ring. Accordingly, the thermal expansion of the inner ring is also greater than that of the outer ring. As a result, the radial clearance of the bearing at operating temperature is smaller than that of the bearing when mounted.

In the literature the following rule of thumb is often mentioned: in general (environment not cooled or heated) a temperature difference of 5 - 10 K can be expected. A temperature difference of 15 - 20 K and more can be expected for bearings whose housings are cooled.

For further information see FVA 364 II Lebensdauer-Industrie-Wälzlager