shear in rolling element bearings

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will a multi visc.gear lube shear down in a rolling element bearing box.application is a mill bearing box calling for a 40 SAE'they are currenly using a 80w 140.Also what would happen if an AGMA EP was used in a gear box calling for a non EP
thanks
 
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Yes I have thought about this,but the current attitude in the maint. dept is pretty apathetic,I'm pushing to get them to consolidate the lubricant suppliers
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and revamp the lubrication program.So in the meantime I'm educating myself(obsessed)
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.They do analysis on one piece of equipt.they change oil monthly,and analyse once every sixth month
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RB,

"will a multi visc.gear lube shear down in a rolling element bearing box.application is a mill bearing box calling for a 40 SAE'they are currenly using a 80w 140."

Under EP conditions and high heat it would shear down, but probably not lower than 75W. I assume the 80W140 has a sufficient EP package. Does the gear box have an oil cooler and a temp guage (thermocouple) to limit temps? A rule of thumb is that the bulk oil temp should be 20C below the highest bearing operating temp. Temp depends of course on load and speed. Talk to the gear-box manufacturer and ask them for the specs on Operating temps. Does the gear box have a pressurized or non-pressurized lube system?

Also what would happen if an AGMA EP was used in a gear box calling for a non EP
thanks.

The parameter here is seal compatibility. There may be a seal compatibility issue in that the seals are not designed to deal with EP packages. If seal cpatibility is not the issue, then an EP gear lube is an added bit of insurance.
 
quote:

Originally posted by RB Shannon:
will a multi visc.gear lube shear down in a rolling element bearing box.application is a mill bearing box calling for a 40 SAE'they are currenly using a 80w 140.Also what would happen if an AGMA EP was used in a gear box calling for a non EP
thanks


RB Shannon,As you might know viscosity is the most important aspect in lubrication. I would not use an SAE 80W140 lubricant in an application that calls for an SAE 40 weight oil. In this application, depending upon how heavily loaded the bearing is, I would use either Schaeffers #112 ISO 150 or #203A ISO 150 grade. Another way to insure that the proper viscosity is being used is to obtain the shaft speed, the inside bearing bore in milimeters or inches and the operating temperature. Once I have those, I can then calculate out the proper viscositiy to use.

You can use an EP gear lube in a gearbox that calls for a non-EP gear lube wthout any harm. The only exception to this rule is if the gear box contains a backstop mechanism. Backsop mechanism is a breaking tyope mechanism and will not function properly when an EP gear lubricant is used. In this case you would use either #112 or #254 in the proper viscosity grade.

http://www.schaefferoil.com/data/112.html
http://www.schaefferoil.com/data/203A.html
http://www.schaefferoil.com/data/254.html

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[ July 06, 2002, 09:54 AM: Message edited by: David ]
 
Thanks Molakule and David,bore is 2.5 in.@1850 rpm.Product pressure into the end of the mill is around 250 psi.I get a dn of 4625,my NTN chart specifies a 100cst visc.But a 150 cst would be better(at least I think so,but I could be wrong)due to axial loading of the shaft and discharge cavitation of the pumps through the mill.
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RB,

I think your maintenance people were going by the old wives tale of "thicker is better."

Problem is, the thicker 80W140 may rob you of input energy (electrical) over the long run, due top viscous friction.
 
" In this application, depending upon how
heavily loaded the bearing is, I would use either Schaeffers #112 ISO 150 or #203A ISO 150 grade. "

An ISO 150 IS a SAE 40W or a 85W gear oil.
 
RB, "Product pressure into the end of the mill is around 250 psi.I
get a dn of 4625,my NTN chart specifies a 100cst visc."

I assume by product pressure you mean the lubricating fluid and not the steel or other processed material?
 
RB,

My AFBMA charts show ISO 60 (SAE 25W EO or SAE 80W Gear OIL) to ISO 300 (SAE 60W EO or SAE 120W Gear Oil), for this bore, application, rotational speed, and assuming a 20C temp rise.

Personally, I would stick with the 80W140 if this gearbox is in a "refractory" situation.
 
The product(ingrediants for dressings and mayonaise)is pumped into the end of the mill(waukasha)and exits from the side of the housing.
All of the load is on the end of the shaft.What are AFBMA charts and where can you get them.
Thanks
 
The AFBMA is (I'm quoting this from the top of my head) the "American Federated Bearing Manufacturers Association?

It's kinda old. Check the web and see if they still exist?
 
I would highly recommend switching from the Multi-vis gear oil and to the optimum single vis for your gear speed, loading, etc.. Very likely a current AGMA or synthetic depending on your operatioan experience with failures, bearing life, gear life, etc. . You have a lot of things you simply do not want or need for this type of gearbox with the current oil. This gear oil is specifically made for heavy duty hypoid gear applications and not a straight gear operation such as this.. Definately do your homework and get the correcti vis/additive package in a single grade industrial gear oil.
 
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