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vibeguy21

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Reply with quote  #16 
sorry Ralph short attention span haha. yes the marking is 360 degrees around the outer and inner race
Danny Harvey

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Reply with quote  #17 
Looking at the picture it seems that you would set the preload on the bearings with circular shims on the drive end just like you do on many gearboxes.

Are you sure that the preload was set correctly?
vibeguy21

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Reply with quote  #18 
I will have to get with the mechanic who rebuilds them and find out. the pump they rebuilt has a tag on it saying bearing set to .008 endplay
Barry

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Reply with quote  #19 
Please recheck that endplay statement. I have never found tapered roller bearings that did not require a preload.
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Ralph Stewart

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Reply with quote  #20 
Quote:
sorry Ralph short attention span haha. yes the marking is 360 degrees around the outer and inner race


Was the impeller end bearing of the pump showing signs of 360 degree wear also on the outer race?

With 0.008 thrust clearance in the axial direction, seems like neither of the two bearings would be showing 360 degree wear pattern on the outer race, inner race possibly, but not the outer race.

I would still check on the bearing type C1, C2, C3, or C4 used on both ends of the pump, and confirm if possible they were actually installed with 0.008 clearance.

May be the wrong type bearings for your application (belt drive).

Also the first picture you attached looks like damage to the inner race due to the ends of the roller being hard pressed against the "collar" of the inner race, but not in a 360 manner.May not be, might be something else.  See the attached closeup of your picture.Vibguy21 bearing.jpg 

Are they running on oil bath or grease?

Seems like the belt driven end bearing would have more of a wear pattern on the outer race in direction of belt tension rather than a 360 wear pattern.

Just my opinion and I could be totally wrong.

Thanks and Have a Great Day,
Ralph

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jpeg Vibguy21 bearing.jpg (20.04 KB, 3 views)


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vibeguy21

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Reply with quote  #21 
that picture is actually the inner race of the outboard(impeller end bearing), for some reason the inboard didn't attach but here it is. the inboard showed more of the 360 wear then the outboard bearing did. these bearings are oil bathed and the mechanic did set it to .008 endplay. IMG_1349.jpg 
Ralph Stewart

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Reply with quote  #22 
Quote:
that picture is actually the inner race


My error. Typed the wrong word. [smile]

Ralph

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weller

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Reply with quote  #23 
If your lube program isn't picking out the bearing fault, i'd re-visit my alarms, testing points ect. That frosting should show up. Unusual to see it in vibration but not in the lube report. What is the ratio of axial to horizontal vibe?
vibeguy21

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Reply with quote  #24 
Capture 4.png 
here is the oil samples. let me know what you think we did change the viscosity from a 100 to 150 the lab hasn't updated it yet


weller

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Reply with quote  #25 
First thing i see is a fluctuation of particle counts from 19k to 2k and back again. Make sure that your getting a good sample. What does new oil look like when sampled? There is an upward trend in iron count with march sample possibly being and outlier of the trend. What is causing a rise in silicon? Is it present in a new sample? Why the visco change? and last ,What oil are you using ? The monthly fluctuation of particle count makes the data suspect.
tomcd3

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Reply with quote  #26 
Tapers don't have a C clearance, you set the clearance or preload during assembly. Not all TRB sets are preloaded. The outer and inner ring both have near perfect 360deg load zones because the clearance was perfectly set at assembly to counteract IR raceway and roller growth thus utilizing the maximum number of rollers for the radial and or thrust loads. See attached life vs. preload/clr diagram.

Tapers are actually radial bearings when paired B2B or F2F and very poor thrust brgs when not as their contact angle is very shallow. Hence their use in this application.

That surface adhesive or abrasive damage is due to poor lubrication and or dirt ingress (e.g. high silicon in your lube report). With abrasive wear comes high iron, chromium and molydenum due to roller and raceway removal.

I don't see the water content in your lube report. I suspect it may be above the 200ppm SKF recommends as a limit. We know that this is hard to obtain, but anything over 500ppm is exceptionally bad for REBrgs as lubricant viscosity, etc. suffer at these levels or greater.

I would have suspected this to be a German pump as both SKF and FAG have TRB factories in Schweinfurt; one of our largest plants globally.

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George D

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Reply with quote  #27 
The previous poster is clearly a bearing guy, thanks for your input.
Curious if a condition of excessive drawup during installation may have resulted in reduced internal clearances here? That, combined with oil contamination, may result in surface initiated fatigue? Could that be what we’re looking at?
Our shop had a little trouble interpreting the installation instructions for a Dodge tapered roller bearing. Caused excessive internal clearance reduction and, I believe, resulted in a 360° load pattern on the cup ring.
tomcd3

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Reply with quote  #28 
Hi George, this is Tom McDermott from SKF. I believe I've been to your generation plant recently for a vertical pump motor failure analysis.

I don't believe this bearing was incorrectly mounted, but I do believe the oil has been contaminated with at least dirt and possibly water. I don't see any fatigue on those pictures, but definitely some surface adhesive/abrasive (microscopic) wear that could lead to that.

These pump TRB's and your DODGE integrated/unitized TRB pillow block are worlds apart with regards to assembly; apples vs. oranges. One can not change the clearance of an SKF unitized SRB or TRB pillow block for the reasons you have mentioned.
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