Hi everybody,

I recently tested 3 vertical motors with Michel tilted pad thrust bearings at the top. One of these showed a different pattern with some sidebands (not around 1X & harmonics).

Could this be a defective bearing? Is there any way of calculating the defect frequencies for these bearings? Do they have any? Or is there some standard pattern?

Any tips would be greatly appreciated.

Best regards,

Aditya

Aditya,
I have worked on a few vertical motors with tilt pad thrust bearings and the design of the bearing would not suggest the possibility of bearing defects. They are made of several pads with babbit faces that run against a top hat which sits on the pads in an axial direction. The pads sit in a ball socket that allows the pad to tilt and stay in line with the top hat. Oil lubricates the pads very much like a sleeve bearing application. I don't know what you are seeing with the sidebands or harmonics. If you could post a spectrum with the sidebands marked, I would be interested in seeing them.
Ronnie Lynn

Ronnie,

Thanks for the interest. I have seen atleast one tilted pad bearing failure till now. That time, the indication was through high acoustic emissions & an elevated vibration peak at 3.1X. When opened the pads were severely damaged (not in this case).

I would be happy to send you the spectra, but I don't see an attach option over here. If you give me an e-mail ID, I'll send it to you.

Thanks for the interest.

Best regards,

Aditya

quote:

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Originally posted by Aditya:
Ronnie,

Thanks for the interest. I have seen atleast one tilted pad bearing failure till now. That time, the indication was through high acoustic emissions & an elevated vibration peak at 3.1X. When opened the pads were severely damaged (not in this case).

I would be happy to send you the spectra, but I don't see an attach option over here. If you give me an e-mail ID, I'll send it to you.

Thanks for the interest.

Best regards,

Aditya

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Michel_Pad_Bearing_Vibration.doc (54 Kb, 18 downloads)

Aditya,
When you click on reply, there is a tool bar on top of the box where you type your reply. The far right icon is a paper clip. When you click on that, it will let you attach several file types. I have attached word files and I belive pdf files as well as pictures will be accepted on this forum.
Ronnie

Hi Ronnie,

I did manage to post the graphs. Did youhave a look at them?

Best regards,

Aditya

quote:

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Originally posted by Ronnie Lynn:
Aditya,
When you click on reply, there is a tool bar on top of the box where you type your reply. The far right icon is a paper clip. When you click on that, it will let you attach several file types. I have attached word files and I belive pdf files as well as pictures will be accepted on this forum.
Ronnie

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Aditya,
When I click on the word file you posted, it will not open for me. Would you try it yourself and if it opens let me know. I have viewed postings of other members but there still might be something wrong on my end.
Sorry,
Ronnie

Aditya,
After replying to you, I tried clicking on the file you posted and it opened for me. I guess I wasn't logged in the first time so it wouldn't let me view it. I don't know what would create the frequency you are seeing or the sidebands. Are you sure your RPM's are marked correctly. .924 times turning speed is not a frequency I have ever encountered before.
Ronnie

Aditya,
I looked at the spectra provided and suggest that the sideband spacing may be related to Pole pass freq around the running speed harmonics. Further investigation of rotor faults may be useful.

Hope this Helps.

Tony S.
Disclaimer: These opinions are my own and not necessarily those of my employer.

Hi Tony,

I'll try checking for that off-line, but I'm not too sure. The 0.924X peak has sidebands, not 1X. Also, I took current signature analysis data on the motors, which is much more reliable for broken bars. There were no strong PPF peaks around the line frequency. If I get something concrete, I'll post it here.

Best regards,

Aditya