OIL "Cushion" for bearings..

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Originally Posted By: Shannow
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Whip is caused when a natural frequency of the shaft, and the dynamics of the bearing get in phase, and the wedge forms and collapses....


Fascinating. I work in sawmill maintenance as a saw filer (saw doctor for ya'll folks down under) and we make effort to keep the saws operating between their "critical speed zones" which are caused by similar dynamics but on a much more readily observable scale. When a forward traveling wave frequency equals a backward traveling wave the saw takes on the shape of a potato chip. Very difficult to cut straight lumber like that.

Thanks for the insight you and other pros bring to this forum,
Joe
 
Originally Posted By: Shannow

SAE 40 had 63% increase in film thickness over SAE10
SAE 40 had 61% increase in power requirement over SAE10
SAE 40 had 5F increase in Delta T (10F in outlet temp)
SAE 40 had 7.5% lower side flow (leakage and cooling)
SAE 40 had 113% more viscosity than SAE10 at working temp.
That's awesome, Shannow, thanks! It is good to see that the % increase in film thickness is approximately the same as the % increase in power requirement. What I'm saying it that, for example, it would suck if it took 200% more power to gain 63% increase in film thickness.
 
Now that we've looked at the main basics of bearing lubrication, it is a good time for the following study to be read: http://www.eng.auburn.edu/~jacksr7/SAE2002013355.pdf
"Lubrication, Tribology & Motorsport"
Author: R.I. Taylor
It has been posted before but this puts it in a good place. It is interesting to note that in the valvetrain in this study for the typical Euro 2.0 Liter engine, the higher viscosity oils reduce the power required to operate it if no friction modifiers are used. This is due to types of lubrication regimes it operates in. In bearings and piston assemblies, the opposite is true.
 
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Now that we've looked at the main basics of bearing lubrication, it is a good time for the following study to be read


Wait a minute!!!! I'm not done here yet
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Let's have an outcomes based educational model ..where the challenged don't feel left behind or left out
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j/k
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Originally Posted By: Gary Allan
Wait a minute!!!! I'm not done here yet
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What do you want to know? Wait, first, here's to beer drinking.
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Originally Posted By: JAG
Originally Posted By: Gary Allan
Wait a minute!!!! I'm not done here yet
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What do you want to know?


I missed the section on paradigm shift in one's personal universe and how to cope with it.

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Wait, first, here's to beer drinking.
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Ah ..there it is.
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Originally Posted By: Shannow
Originally Posted By: Steve S
Shannow is the 10c change in temps a drop or increase?


Increase, viscosity drops, wedge gets thinner and stiffer.
Amazing!!!
 
Originally Posted By: JAG
I'm thankful that others have responded to Gary's question to me.
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I've been off-line. Gary, I agree with what you said:
"I imagine it would show me that certain things that I'm suggesting cannot occur."

I don't know for sure but I imagine that as well. I learned in college that questioning some things in science/math/engineering TOO MUCH can get me wrapped around the axle. Trying to develop an alternate method as your question would lead you to, would be a hair-pulling exercise.

This has been an unusually informative thread, thanks to many.


Kind of bummed out that I wasn't on this forum earlier. Missed out on all the intelligent discussions and relevant facts presented and only stumbling upon them occasionally.
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Lot's of reading to do.
 
Originally Posted By: Shannow
Originally Posted By: Gary Allan
I do thank you and Shannow for your patience. I'm arguing points that are conceptual road blocks that will take a longer process to piece together and get through. No one is taking the rhetorical bait
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Thinner oil/more offset/more leakage
Double volume/same offset/much mo leakage

A very intuitive concept
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Seeing as I'm having the day off, I worked through the example at the end of the spreadsheet that Gary and JAG posted, of the SAE 10 and 40 weight oils in the same.

Results were (note, too many significant figures for the printed graphs)
SAE 40 had 63% increase in film thickness over SAE10
SAE 40 had 61% increase in power requirement over SAE10
SAE 40 had 5F increase in Delta T (10F in outlet temp)
SAE 40 had 7.5% lower side flow (leakage and cooling)
SAE 40 had 113% more viscosity than SAE10 at working temp.

And having used the graphs in the spreadsheet, I'm Soooo glad that I studied in S.I....no wonder things run into Mars every now and then.


Quoted to rebump the thread, as some seem to be having difficulties grasping a few concepts.

Been back and check, and the links are mostly broken.

However, this presetnation goes over the basics
 
Thank you Shannow. Just took a peek at this thread and can't wait to read it tomorrow (too sleepy to get into it now).

Very timely thread for me.

You sure have a knack for putting up good stuff when my day is ending and I'm too tired to read.
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