Included in this presentation are 4 case studies:

1. Commissioning of a New Motor on a Hoffman Blower
   • An electrical contactor remains closed after starting the motor. This has the effect of leaving an undesirable circuit impedance.
2. High vibration readings from a mining main hoist
   • When gears are getting worn out, we can find sub harmonics of the gearmesh in the common factor.
3. Abnormal condition of the bearings of the recently installed motor of a hoist.
   • Wrong grease used in motor. Thicker grease causes the roller to slip on the bearing race instead of turning.
4. Small blower with pillow blocks, repetitive failures.
   • Wrong bearing used for this application.