It went away for a few months, now it is back. It will be overhauled tomorrow so I'll get to take some pictures.

Centri_screen_bearing.ppt (234 KB, 108 downloads) Bill Kilbey slow speed bearing defect

Maybe it went on vacation I have only seen a couple do that, one ball bearing where the damage on the ball sometimes didn´t pass the load zone but was pointing axial and another outer race in a rolling mill motor where it only was found during startup, in operation load zone was outside the damaged area until it eventually extended in to that too. Maybe something like that for some reason. Interesting to see. OLI

My guess is the outer race crawled in the housing and has now reached the same position it left a few months earlier. Of course it may have crawled through the load zone several times but just was not checked during that time.

I agree with Ralph, when I have seen that happen in the past, the outer race was creeping in the housing. If this is the case, I would expect to see evidence of scraping of the outer ring with the housing.

Here is a fan pump that I believe the outter race was creeping in the housing. Unfortunately I never received a confirmation on it.

Ronnie

7_Fan_Pump.doc (92 KB, 36 downloads) #7 Fan Pump Outboard Bearing

One of the bearing's grease lines were rotted/not connected, so it will probably be wrecked. Here is a picture. They will hopefully take it apart for rebuild this week so I can get a look at the bearings.

quote:

It went away for a few months, now it is back.

Bill,

If the geometry has changed due to a "wreck", the "return" would not be there would it?

Guess it depends on the stage of "wreck", or the definition of "wreck", huh?

Ralph,
Good point.maybe one is in worse shape from no lube for a year.

They rebuilt it today. bottom bearing was "wrecked" .

Centri_screen_bearing.pdf (684 KB, 38 downloads) Bill Kilbey slow speed screen brg defect

bottom bearing

bottom brg outer race

Bill,

That was a good catch but, in whole honesty, a trivial case, thanks to PeakVue.

Was the 'fault disappearance' effect ever explained based on post mortem analysis?

David

David,

With .07 Gs in the PV spectrum and 2 Gs in the PV waveform, I think a lot of people would have let this one go longer. I dont think it would have run much longer.

I prefer to think it was my attention to detail (and good instrumentation) that made it "trivial" . I dont have a good explanation for the disappearance of the fault frequency energy. It is constant speed, constant load and I use the same accel in the same location every month.

This message has been edited. Last edited by: Bill Kilbey,

quote:

Originally posted by Bill Kilbey:

With .07 Gs in the PV spectrum and 2 Gs in the PV waveform, I think a lot of people would have let this one go longer. I dont think it would have run much longer.

This fact brings up a point which I was always in favor: absolute numbers in a high frequency measurement and on a low speed equipment, in particular, mean little. Instead, pay attention to the pattern, trend, signal-to-noise ratio, crest factor. If that is what you mean by saying 'attention to details' I do agree.

David

David

Is this the bearing with the broke grease line?

Was there no sign that the race crawled out of the load zone, not necessarily on the out side of the race, but more so with a small indication that the rollers had contacted the race for a short time in more than the area shown in the picture?