Oil & Fuel Motor Oil as the Hydraulic Oil in Power Trac

[DieselPower]

Well said JJ.

 

[Barryh]

>>>You probably have heard that sound that sounds like a groan or whine, that is the sound of your pump cavitating, and you should back off what you are doing, because after that point, the pump and motors will lose efficiency.<<<

J.J. So you are recommending Hydraulic over Synthetic? I didn't realize this sound meant there might be on going damage to the pumps. How many hours or a period of time would you say it might take to do any significant damage??

So if I change over to Hydraulic oil this sound would be reduced, or will go away for the most part ??

 

[pajoube]

David,

I have had foaming and leakage around the top seal of the hydraulic reservoir.
I attribute this in part to my high elevation and warm temperatures during the summer.
With that said, I probably will stay with the recommended 10 40 oil as I do not see any starting (cold weather) problems.

PJ

 

[J_J]

>>>You probably have heard that sound that sounds like a groan or whine, that is the sound of your pump cavitating, and you should back off what you are doing, because after that point, the pump and motors will lose efficiency.<<<

J.J. So you are recommending Hydraulic over Synthetic? I didn't realize this sound meant there might be on going damage to the pumps. How many hours or a period of time would you say it might take to do any significant damage??

So if I change over to Hydraulic oil this sound would be reduced, or will go away for the most part ??

AMSOIL - Synthetic Tractor Hydraulic/Transmission Oil, SAE 5W-30

The web site above has some info that you might can use.

You can have synthetic hydraulic fluid, and it is probably the best fluid for any hydraulics. You have to match up your requirements with the fluid. For instance, I could get by with a single weight synthetic fluid in the South, whereas you guys in the colder climates would require a multi-viscosity fluid.
Synthetic hyd fluid is probably the best you can get at the present, having all the additives necessary for functionality and longevity. I have considered changing over, but my system which has a 20 gal tank , would cost big bucks.

The cavitation probably will not go away, but may be reduced by using a more dense fluid.

Some one mentioned foaming. That is usually caused by water or air in the system. The water could come from condensation inside the tank, or hyd tank cap, and air from a suction leak. It is simply a choice we have to make using as much knowledge as one can get.

 

[SPYDERLK]

Quote: On the subject of cavitation, this is caused by excessive pressure in pumps and motors, and is not a good thing.

Cavitation is caused by the pressure being too low on the suction side of the system. This causes bubbles to form - the fluid essentially begins to boil without getting any hotter. When these bubbles get to the pressure side they implode. Those that do so against surfaces cause erosion of the surface. If you hear cavitation, lower your rpm until the system warms. Also, check your suction side for restriction, go to a lighter fluid, etc.
larry

 

[J_J]

Just some more data on cavitation.

Suction cavitation
Suction cavitation occurs when the pump suction is under a low pressure/high vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition has large chunks of material removed from its face causing premature failure of the pump.


[edit] Discharge cavitation
Discharge cavitation occurs when the pump discharge pressure is extremely high, normally occurring in a pump that is running at less than 10% of its best efficiency point. The high discharge pressure causes the majority of the fluid to circulate inside the pump instead of being allowed to flow out the discharge. As the liquid flows around the impeller it must pass through the small clearance between the impeller and the pump cutwater at extremely high velocity. This velocity causes a vacuum to develop at the cutwater (similar to what occurs in a venturi) which turns the liquid into a vapor. A pump that has been operating under these conditions shows premature wear of the impeller vane tips and the pump cutwater. In addition, due to the high pressure conditions, premature failure of the pump's mechanical seal and bearings can be expected. Under extreme conditions, this can break the impeller shaft.

Discharge cavitation is believed to be the cause of the cracking of joints.Serious damages are caused by cavitation

 

[SPYDERLK]

JJ, good. I am aware of the possibility of discharge cavitation just as you describe in centrifugal pumps. These operate at very low pressure compared to hyd systems. I cant imagine, tho, the conditions at which discharge cavitation would occur in a hydraulic pump since it is positive displacement - sending out almost 100% of its displacement per revolution regardless of pressure. At the pressure required to cause enuf bleedback velocity to lower the pressure in the bleedback fluid from kpsi into the hi vacuum range, the pump shaft would twist off. The system relief valve, if working at all, will prevent such destructive pressures.
larry

 

[davemhughes]

My neighbor swears he uses a mix of synthetic Mobil 5w/30w motor oil and UTF in his tractor.

 

[pah]

Maybe I'm being to cynical but is it possible Power-trac uses motor oil because it's easier and cheaper for them? much cheaper!

 

[DieselPower]

In so many words that's the impression I got.