Bearings carry the impeller and absorb the loads from imbalance, belt tension and thermal expansion, so they are usually the first component to wear out. The two big factors in bearing life are vibration — driven mostly by impeller balance — and lubrication. A well-balanced impeller dramatically reduces the dynamic load on the bearings, which is one practical reason we balance every fan to G6.3.
Correct lubrication intervals, clean grease and keeping the bearing within its temperature rating do the rest. For continuous-duty fans we recommend a simple condition-monitoring routine — checking temperature and vibration — so a bearing can be changed on schedule rather than failing on the line. Matched spare bearings are part of the spares program we supply.