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Hi. I am trying to figure out why I ainΒ΄t seeing clear bearing defects. Motor sounded awful and obvious clearance ( I could move the axle littlebit )

I also checked old FFT and nothing that I could see...cut maybe I am missing something.

In this FFT for NDE H motor is running free. Note very high 2X and hardly any 1X. Bad sound from motor but nothing noticeable from acceleration spectrum ( bearing foults )

Here is DE Vertical, again high 2X and floor rising. Is it possible that bearing is in such bad condition that bearing frequency is not seen

And DE Horizontal. Again very very high 2X

Here we see DE Axial, and Ball Pass Frequency outer race is seen now.  Motor is also running free ( no coupling )

And last one...

Here Motor is coupled with fan. Now 1,5 X appear...I have no clue what it could be.

Different speed this time 2400 rpm/40Hz

If I am missing some information please let me know.

400V/50hz motor - 2980RPM. 6314 SKF DE & NDE



IMG_4634-1209x907

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Last edited by Registered Member
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@Registered Member posted:

Hi. I am trying to figure out why I ainΒ΄t seeing clear bearing defects. Motor sounded awful and obvious clearance ( I could move the axle littlebit )

I also checked old FFT and nothing that I could see...cut maybe I am missing something.

I can not see the images you have at the beginning of you posting......

Is it my computer or is they some other reason?

Thanks Ralph

In this FFT for NDE H motor is running free. Note very high 2X and hardly any 1X. Bad sound from motor but nothing noticeable from acceleration spectrum ( bearing foults )

Here is DE Vertical, again high 2X and floor rising. Is it possible that bearing is in such bad condition that bearing frequency is not seen

And DE Horizontal. Again very very high 2X

Here we see DE Axial, and Ball Pass Frequency outer race is seen now.  Motor is also running free ( no coupling )

And last one...

Here Motor is coupled with fan. Now 1,5 X appear...I have no clue what it could be.

Different speed this time 2400 rpm/40Hz

If I am missing some information please let me know.

400V/50hz motor - 2980RPM. 6314 SKF DE & NDE



IMG_4634-1209x907

@Registered Member posted:

Yes...you are right. These spikes have 15,4 hz between them. Why appear Cage (1x) so small

The cage's duty is really to basically keep the balls/rollers in "position" as they (the balls/rollers) travel around the inner and outer races.  The cage usually responses at its fundamental frequency when some other defect is present and "excites" the ftf. A bad ball or roller does this quite easily. IMO.

I have seen but one (1) case where the ftf was showing in the data with no other visible bearing defect frequencies showing. When the bearing was removed, there were no race or roller defects present. The bearing had a machine brass type cage and was cracked on the outer race side of one roller.

I saw another case (on a felt roll in a paper machine) with data similar to your data and when the machine was shutdown about 2 weeks after I reported it, the cage was completely destroyed and not even a piece of the metal cage was left in the bearing. The rollers were rolling against one another.

Thanks for the reply,

Ralph

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