"high shear" rating vs. temperature???

[Curious Kid]

As there is the well known HTHS @ 150 deg. c, I was wondering how this value would compare at other temperatures. I'd guess higher at lower temperatures and so forth...and is there any mathematical formula that could be used to be more specific, or is actual testing an oil the only way with the general information that is given?

Thanks in advance.

 

[MolaKule]

Generally speaking, HTHS is higher at higher temperatures and lower at lower temperatures.

 

[Curious Kid]

Very interesting.

Would someone like to explain how that is?

Thanks again.

 

[MolaKule]

quote:

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Generally speaking, HTHS is higher at higher temperatures and lower at lower temperatures.

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Should have read:

Generally speaking, HTHS is lower at higher temperatures and higher at lower temperatures.


Oil at higher temp will shear more easily and conversely, shear less easily as temp is reduced.

 

[moribundman]

How does the fact that oil becomes essentially a solid under high pressure figure into this?

 

[Curious Kid]

Interesting point mor, but would it be probable to say that it's more likely for such stiffening of the oil wedge to occur in a roller element bearing rather than a plain bearing?

 

[moribundman]

I have no idea. At least I brought it up. The mor has done his work; the mor can go." ;-)

 

[deuginthesky]

Is HTHS the viscosity @ 150°C or is it something more complicated ?

 

[Mitch Alsup]

quote:

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Originally posted by deuginthesky:
Is HTHS the viscosity @ 150°C or is it something more complicated ?

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It is a little more complicated: A) it is measured in cP rather than cSt, B) it is measured wile 10**6 shearing per second are happening to the oil.

Anyone know why the regular numbers are measured in cSt and HTHS is measured in cP?