
Problems such as imbalance, misalignment, resonance, bearing condition, looseness, poor mesh of gears (due to wear or damage), excessive clearance, poor assembly etc. can all be detected by fault diagnosis using the appropriate equipment
The following spectrum was generated by a bearing containing the above bearing element two weeks before it's removal. The bearing had been diagnosed as faulty 6 months previously and monitored closely. This enabled maintenance to be carried out when it became necessary, but without the need for an unsceduled plant shut-down or risking possible secondary problems often associated with bearing failure.
Main Hoist spectra

Click on Image to enlarge
A sister plant suffered a Catastrophic failure 8 months after monitoring had been discontinued. The plant was down for several days waiting for an expensive replacement gearbox to arrive from the U.K. The reason given for discontinuation of monitoring was that it was no longer considered necessary (the actual reason was to improve cashflow figures). This cost the company in excess of one million dollars.