Application support - Vibration analysis of cycloid gearbox

[Parthiban_SM]

Hi,

I need help identifying the vibration-producing component in a cycloid gearbox. I'm looking for clarification on how to extract information from the frequency spectrum. We have a custom-built noise and vibration measurement setup with NI hardware and LabVIEW software.

Testing conditions:

• Gearbox ratio: 33
• Input speed: 3000 RPM
• Testing: Without load run

Measurement setup details:

• Sampling frequency: 12,800 Hz
• Data collection time: 10 seconds

Questions:

1. Usable frequency range:
   In the reference image, How much of the frequency spectrum is usable for analysis?
2. Peak frequency:
   The peak value is around 3350 Hz, but this does not correspond to any combination of gearbox frequencies. How should I relate this peak frequency to the actual gearbox frequency?
3. Multiple of input speed:
   I noticed a repeated pattern at multiples of the input speed (3000/60 = 50, 150, 250, 350... up to X50). How many values of X should I consider in the frequency spectrum for analysis?
4. Theoretical frequency derivation:
   I’ve already referred to the AGMA white paper, which focuses on reference value comparison. However, I’m looking for a theoretical derivation of the reference values themselves. Any help with this would be greatly appreciated.

Please let me know if you need further details regarding the gearbox or test conditions.

Thanks in advance!

[Parthiban_SM]

Sorry correction in my 3rd question

3.Multiple of input speed:
I noticed a repeated pattern at multiples of the input speed (3000 RPM/60 = 50Hz, 1*50, 2*50, 3*50... up to X50). How many values of X should I consider in the frequency spectrum for analysis?

[dsb@NI]

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@Parthiban_SM wrote:

Hi,

I need help identifying the vibration-producing component in a cycloid gearbox. I'm looking for clarification on how to extract information from the frequency spectrum. We have a custom-built noise and vibration measurement setup with NI hardware and LabVIEW software.

Testing conditions:

• Gearbox ratio: 33
• Input speed: 3000 RPM
• Testing: Without load run

Measurement setup details:

• Sampling frequency: 12,800 Hz
• Data collection time: 10 seconds

Questions:

1. Usable frequency range:
   In the reference image, How much of the frequency spectrum is usable for analysis?
2. Peak frequency:
   The peak value is around 3350 Hz, but this does not correspond to any combination of gearbox frequencies. How should I relate this peak frequency to the actual gearbox frequency?
3. Multiple of input speed:
   I noticed a repeated pattern at multiples of the input speed (3000/60 = 50, 150, 250, 350... up to X50). How many values of X should I consider in the frequency spectrum for analysis?
4. Theoretical frequency derivation:
   I’ve already referred to the AGMA white paper, which focuses on reference value comparison. However, I’m looking for a theoretical derivation of the reference values themselves. Any help with this would be greatly appreciated.

Please let me know if you need further details regarding the gearbox or test conditions.

Thanks in advance!

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1. The usable portion of the spectrum depends on your signal path and the antialiasing filter in your dynamic signal acquisition system. If you are using a device such as the PXIe 4464, the alias-free bandwidth is provided in the specs:
   
   so you would be able to measure up to 0.454 * 204.8k Hz = 92.98k Hz
   Same spec lookup and math can be applied to your hardware (Alias-Free Bandwidth * Sample Rate).
2. Relating energy at 3350 Hz to your specific cycloid gear box running at a nominal 50 Hz depends on the specifics of your gearbox. Have you been able to identify the culprit?
3. The maximum order of interest is also based on the specifics of your gearbox. The gearbox specifications may even include 'orders of interest'.
4. Derivations are built into many online cycloid gear calculators (such as https://www.csparks.com/watchmaking/CycloidalGears/CycloidCalculator.html), but I don't have the background to help with this request.

From the reference you attached:
"Conclusion
Since some cycloidal operating frequencies are unknown, it can be difficult to review a single vibration graph and determine which specific internal components are worn. Cycloidal eccentric  bearing fundamental train frequencies and discmesh frequencies can be calculated, however. We also know that rolling element faults may reveal themselves by creating high frequency vibrations that may also include sidebands (2,3). ..."
So it seems highly unlikely that we will be able to review your single vibration graph and determine which specific internal components are worn.

Perhaps it would be worthwhile to reach out to the authors of that paper, or review the references cited in the paper...

[Parthiban_SM]

It’s been one year since I started learning about instrumentation, and I really want to understand noise and vibration measurement. Due to a lack of expertise, the results have not been satisfactory because of a knowledge gap. I would like to know the learning flow—where to start (e.g., 1. sensor working principles, 2. measurement devices, 3. wiring practices, 4. signal acquisition, 5. processing, etc.). Please recommend a study flow (from start to end) along with study material references to help me achieve expertise in this domain. I would greatly appreciate your support

[dsb@NI]

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@Parthiban_SM wrote:

It’s been one year since I started learning about instrumentation, and I really want to understand noise and vibration measurement. Due to a lack of expertise, the results have not been satisfactory because of a knowledge gap. I would like to know the learning flow—where to start (e.g., 1. sensor working principles, 2. measurement devices, 3. wiring practices, 4. signal acquisition, 5. processing, etc.). Please recommend a study flow (from start to end) along with study material references to help me achieve expertise in this domain. I would greatly appreciate your support

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I recommend creating a new topic for this question. Dynamic Signal Acquisition seems like the most relevant board.

[Parthiban_SM]

As per your recommendation, I have posted my question under the respective topic. Thank you for the support