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In this study, an example of the results obtained from the combination of the vibration monitoring program and the root cause analysis approach for the electromotor roller element bearings of the cement factory’s mill fan has been presented and examined. By registering the inspectors' reports on the release of abnormal sound from the bearings, the vibration data recorded in the monitoring program were equipped and, by carefully checking the vibration trends of the machine, sensible increase in the bearing condition index (BC) have seen. By matching the fault frequency with the frequency elements of the roller bearing, predicted is failure in the bearing' cage, which will be verified by visited and reviewed. The detect of the root cause of the failure is on the agenda for this purpose, paid investigated the causes of failure in the bearings and due to the inspection history, finally specified the use of the bearing is not suitable due to the velocity factor, as well as the factors of the lubrication interval and the amount of lubrication charged can be explained by the reasons for failure in the machine.