Categories: Machinery Diagnostics,Condition Monitoring,Machinery Maintenance,Other Topics

Using Bearing Defect Factor for Gear Defect Detection

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By on October 12, 2017

Bearing defect factor is a culmination of two technologies used for shock detection.  DEF is designed as an indicator for bearing defect detection, but can also be valuable in the detection of gear defects.

Why is DEF significant?

In the following data set are displayed Overall Vibration Velocity, Overall Acceleration, and Defect Factor.  The Overall Vibration Velocity alarm values correspond to ISO 10816-3 whereas none of these values are in alarm.

Due to the high values recorded with the DEF indicator, the waveform was viewed with the indication of shocks at 6.89 Hz.  The operating speed of this unit corresponds to the repetition rate of the shocks with the indication of a gear defect on the pinion.

If ISO values alone were used for an indication of overall machinery health, this gearbox would have been deemed in good operating condition with an imminent machine failure.

About the Author

Tim Sorensen has over 37 years’ experience in alignment and vibration analysis of industrial machinery. He joined VibrAlign in 1992 as a Field Service Technician until 2008. Tim rejoined VibrAlign in 2016 as a Vibration Analyst and Alignment Specialist. Before joining VibrAlign Tim worked as a HVAC Supervisor with The Common Wealth of Virginia and the U.S. Navy.

Tim is a Category III Vibration Analyst and is certified in Vibration Testing. He also holds a Virginia Board of Contractors Tradesman’s license for HVAC.

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