Gearbox Condition Monitoring Questions
I was asked the following question recently by Gourav who was trying to do condition monitoring of Gearbox and ball bearing. Here are his questions:
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While we run the motor and place the sensor on top of the Gearbox the vibration, it will capture due to all system attached to the motor not just by Gearbox and Bearing. So, how to find out the important signal?
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What all parameters, features of the signal I should consider? What will be a good way to do it?
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How to find that some fault has occurred?
- How to distinguish between types of fault?
I want to use Python for signal analysis and trying to do it in real time.
Please guide me.
Answer: Gourav, these are great questions! I did a bit of searching online and found a great article I've attached and cited below.
Summary
In this paper they go through a few different analysis methods, summarized with this graphic:
If I were in your shoes I'd start with the frequency domain, focusing on dominant frequency and corresponding amplitude. You may also be able to see a lot from simple RMS vibration levels. But the trouble is you need to start measuring known good and _bad _ gearboxes, then looking for differences in the frequency domain and/or RMS vibration levels (or other analysis methods) for differences.
Hope this helps!
References
S. Sait, Abdulrahman & Sharaf-Eldeen, Yahya. (2011). A Review of Gearbox Condition Monitoring Based on vibration Analysis Techniques Diagnostics and Prognostics. 10.1007/978-1-4419-9428-8_25.
"This is typically a field that requires some time to become familiar with all the techniques. I would start with the book "Vibration based Condition Monitoring" by Robert Randell. This is a wealth of material that could not be posted on a blog.
Then you can look at what others do. The Tensor Systems commercial system does the resampling of the time domain data into the angle domain, calculates orders, looks for bearing frequencies, and integrates the most popular gear mesh algorithms that Steve mentioned in his post. In short it does much of what the book above suggests.
Finally you will need to determine the alarm levels.
I suspect that the first thing however is to find a mentor, someone that will guide you through this process."
Response (Steve Hanly) Thanks, Jake for the wise words! If I may, I'd like to recommend Jake as that "mentor!" He wrote a fantastic in-depth blog on Condition Monitoring of Bearings that relies on similar analysis techniques that would be useful for pumps.
Jake has his own consulting business that is worth checking out if you need further assistance. He's a valuable resource!