Effect of air bubbles in lubricating oil for gearbox 2

[jmcx]

I'm loking after technical data about the oil emulsion (air bubbles) when used for gears lubricating and journal bearing.

Is there any risk for scuffing or surface effect like piting


Thank's

 

[unclesyd]

Bubbles are very detrimental to any lubrication system as it lowers the effective lubricity of the oil. You need to find out the source of the air intrusion and eliminate it. This could also mean that you have some contaminate that is causing the oil to entrain air, very bad.

Come back with a little more details of your system.

 

[jmcx]

The oil system comprises two pumps,
the main pump is a mechanically driven pump based one three screw witch induce foaming. We usually use another pump (based one two screw)
second one (for safety and low speed) is an electric one and is very well known

My experience shows that a (very)little quantity of air bubbles is not to dangerous my question is what will happen with 5%, 10% ?
Are they some experimental results on the evolution of viscosity and thermal efficiency of the lubricating oil

Thank's

 

[unclesyd]

I would get with your oil supplier and see if he has a similar oil with a better additive package.

Also check with the oil pump manufacturer concerning your problem with air bubbles, he may have a fix.

I have never seen a paper on the permissible amount of air in oil. One has too many variables in each system to say the a certain percentage of air is acceptable or not.

We usually got concerned if we could see any air bubbles in a system.

 

[jmw]

Some of the specialist racing teams in the UK use entrained gas densitometers to measure the density of the oil in test applications. There is a special algorithm that they use to determine the quantity of entrained air that involves the pressure as well (because of compressibility) but i don't have this. If anyone knows what it is, I'd like to know.
I know also that one of the car manufacturers does the same testing, possibly BMW.

JMW

http://www.viscoanalyser.com

Eng-Tips: Pro bono publico, by engineers, for engineers.

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.