Diagnosing Gearbox Defects

by | Jul 11, 2019 | Asset Management | 0 comments

In earlier posts, Emerson’s Robert Skeirik highlighted how PeakVue impact detection analytics technology can provide early warning of bearing failure in time to plan and schedule maintenance before unplanned downtime occurs. These analytics help drive overall reliability improvement key performance indicators (KPIs).

I came across a recently published whitepaper, Confirming Gearbox Defect Using Waveform & PeakVue Technology, which highlights another issue with rotating machinery that this diagnostic in combination with time-series waveform analysis can help identify.

Gearbox defects may not exhibit repetitive, periodic defects like ball bearing defects exhibit. Analyzing vibration in the time domain helps provide insights beyond the typical frequency spectral analysis.

Here is some case study information from the whitepaper:

Data collected on a gearbox indicates an abnormal gear issue. The conventional vibration waveform had indicated only slightly higher levels of impacting at once per revolution, however, a peak of over 19 G’s is present in this PeakVue waveform.

The whitepaper goes on to share how the time-based waveform shows a large impact once for each revolution and how this might indicate a problem with the gear such as a broken or missing tooth. When viewed with a circular waveform plot, it provided:

…further confirmation of a broken tooth. The 1 X TS event offsets the circular autocorrelation waveform at a probability of one (or close to one) at the Top Dead Center (TDC) of the circular plot.

Read the short whitepaper to see the waveforms on how the problem inside the gearbox was detected and confirmed after disassembly and inspection. For those here in North America there is an upcoming 3-day course, Time Waveform Analysis, in Knoxville, Tennessee in early August and another in December. The course:

Time Waveform Analysis Educational Course…is designed to upgrade and enhance waveform analysis skills for vibration technicians and reliability engineers. There are several reasons that vibration analysts want to understand and use waveform analysis, since some significant defects are better analyzed in the time domain. The time domain provides visual confirmation of amplitude enhancement and reduction. Time waveform analysis can present, in a static picture, amplitude variations and changes in frequencies that the FFT cannot display without using multiple (dynamic) graphics. Further, a waveform graphically presents accurate peak vibration amplitudes representing defect severity.

Visit the PeakVue Technology for Machinery Analysis section on Emerson.com for more on these analytics technologies and how they help you drive improved performance in reliability and overall equipment effectiveness (OEE). You can also connect and interact with machinery health experts in the Asset Management group in the Emerson Exchange 365 community and/or at the September 23-27 Emerson Exchange conference in Nashville.

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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.

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