front axle lubricant question

[Jeff F.]

Heat from the friction.... makes sense. I did not expect it to get that hot. Today was not wasted after all.

 

[megaboz]

I still do not understand where the oil pressure is coming from or why you would need to relieve pressure on the front drive by opening a cap. Is it the air pressure? I thought it is an oil bath system. I understand the pressure of the friction of metal on metal in the gears, but I do not understand how that would build up in the sealed front end. :confused3:

As the oil heats up from friction the expansion of the fluid causes air pressure to increase.

 

[sw03]

Heat from the friction.... makes sense. I did not expect it to get that hot. Today was not wasted after all.

Basic design issue. I think of this like a gas tank, you open the cap and hear what? That is a sealed system but with better seals. Or leave a 5-gallon gas can in your shed on a hot day. Kubota missed the boat on the front diff seals yet again. So much for their "kaizen" principles. Really sad in my eyes.

 

[chopped]

Yes there is pressure I had to replace my dipstick /cap and make a 'ventable' pvc fitting. otherwise the seals would leak from the pressure.. its amazing how much pressure is developed..

 

[sixdogs]

Wouldn't you want to leave the pressure, or a degree of it to prevent a negative or neutral pressure situation that would draw dirt into to housing? The fact of a sealed system that would build and retain some pressure by design?

 

[JOHNTHOMAS]

Same principle as your car/truck drive axle, splash system where oil is carried by the gears up into the case and then channeled by casing moldings to the bearing areas.

Next question. The dip stick cap is sitting on top of the axel with a very short dip tick. Pull that dipstick out and see the oil level. If the oil inside is where the level is showing on the dipstick cold then it appears that most of the axel/gears are immersed in oil and not just some hanging around near the bottom. Also with the heat buildup and that almost always brings expansion but almost all of mine have checked at the same level on the dipstick, hot or cold. Something isn't seeming right in amongst all these different answers. .:confused2: :confused3:

 

[Bluegill2]

Next question. The dip stick cap is sitting on top of the axel with a very short dip tick. Pull that dipstick out and see the oil level. If the oil inside is where the level is showing on the dipstick cold then it appears that most of the axel/gears are immersed in oil and not just some hanging around near the bottom. Also with the heat buildup and that almost always brings expansion but almost all of mine have checked at the same level on the dipstick, hot or cold. Something isn't seeming right in amongst all these different answers. .:confused2: :confused3:

You are right. Most of the gears and bearings are below oil level. I believe the top third of the ring gear is above oil level, but as it turns it gets more than enough oil.

There really is no problem here at all...