Correct installation method of bearing
Installed back-to-back in pairs, the two bearing in the middle are installed face-to-face. As mentioned above, during operation, the temperature difference causes the preload of these inner bearings to increase. This installation method is not recommended.
When the shaft temperature is higher than the bearing pedestal, excessive axial load is generated on the two outer bearings. The two inner bearings have no load, resulting in a vicious cycle of increasing temperature rise, increasing preload and damaging lubricant, which is also an unacceptable installation arrangement and is also not recommended.
The bearings correctly installed in series and arranged back-to-back are shown in Figure 91. The axial expansion of such installed shaft and inner ring spacer does not increase the axial load or bearing preload.
Therefore, in order to prevent the increase of preload caused by thermal expansion, the bearing for bearing the machine tool spindle is best installed back-to-back. When two pairs of bearings are used, each pair shall be installed in series, but the arrangement is back-to-back.
