how hot is hydraulic oil supposed to get

[Dave M7040]

Before starting, I admire your ingenuity.

What is puzzling me is the sound I am hearing when your machine is stationary.

What type of hydraulic pump are you using? A simple gear pump or a variable displacement pump.

Is it possible, the hydraulic system is maintaining pressure even when the splittler is not moving.

Ordinary log splitters, albeit a little smaller than your piston, manage to maintain reasonable temps with a modest reservoir radiating heat.

I would just want to be certain, for example, if you used a flow divider to independently power the movement of the overall machine from the splitter that part of the system is keeping the pump pressure high and dumping through a relief valve which will generate heat in a hurry

Dave M7040

 

[wdchyd]

In my experience hydraulics that go from high pressure to low pressure (pressure drop) without doing any work is making heat.

I would guess somewhere you have too much back pressure when valves are in neutral position ( hoses or fittings too small or control valve restriction through the core) or some of your circuits are seeing too much oil blowing over relief valves. Presssure gauges moved in different spots may help expose the culprit.

 

[RickB]

I too have been wondering about the hydraulic oil temp. Would anyone know where would be the best place to install the sending unit?

It would be on a Kubota L4330. Thanks

I would put it in the motor return line.

 

[Dave M7040]

I too have been wondering about the hydraulic oil temp. Would anyone know where would be the best place to install the sending unit?

It would be on a Kubota L4330. Thanks

Just putting your hand on the transmission case will give you a good idea of what is happening temperature wise in the hydraulic system.
At 130 F you will want to remove your hand from the metal quickly.

It can get much hotter than that and still be fine......

Unless you are using your tractor in an unusual way, relax in the fact that Kubota tested it in ambient temperatures that would make most people faint.

Dave M7040

 

[nyone]

Usualy your hydraulic tank has 1gal capacity per GPM of hyd pump. It can be smaller if its only occasionally use.

I built a log splitter with 22gpm pump and put a 15gal hydraulic tank on it. I dont use the thing the whole day. But the tank does get hot

 

[drizler]

Hot enough to make you scream when a hose breaks and you get a bath.............

 

[triptester]

How hot is too hot? Hydraulic fluid temperatures above 180°F (82°C) damage most seal compounds and accelerate degradation of the oil. While the operation of any hydraulic system at temperatures above 180°F should be avoided, fluid temperature is too high when viscosity falls below the optimum value for the hydraulic system’s components. This can occur well below 180°F, depending on the fluid’s viscosity grade.
A temperature of 130 -140 F would be optimum.

 

[RickB]

How hot is too hot? Hydraulic fluid temperatures above 180°F (82°C) damage most seal compounds and accelerate degradation of the oil. While the operation of any hydraulic system at temperatures above 180°F should be avoided, fluid temperature is too high when viscosity falls below the optimum value for the hydraulic system’s components. This can occur well below 180°F, depending on the fluid’s viscosity grade.
A temperature of 130 -140 F would be optimum.

Generally not practical or attainable for sustained operation of most systems. Your target is 30-50 degrees too low.

 

[Tx Jim]

Generally not practical or attainable for sustained operation of most systems. Your target is 30-50 degrees too low.

I agree 130-140 degree hyd oil when operating isn't going to happen for any length of time on most days

 

[Roger66]

Before starting, I admire your ingenuity.

What is puzzling me is the sound I am hearing when your machine is stationary.

What type of hydraulic pump are you using? A simple gear pump or a variable displacement pump.

Is it possible, the hydraulic system is maintaining pressure even when the splittler is not moving.

Ordinary log splitters, albeit a little smaller than your piston, manage to maintain reasonable temps with a modest reservoir radiating heat.

I would just want to be certain, for example, if you used a flow divider to independently power the movement of the overall machine from the splitter that part of the system is keeping the pump pressure high and dumping through a relief valve which will generate heat in a hurry

Dave M7040

This machine uses a triple fixed displacement pump. I believe all in it's moving about 50 gallons per minute. It's always pumping, but the valve body returns to the tank when no valve is open. I combine all 3 pumps for the splitter valve, but I have pressure sensors and valves that relieve 2 of the sections once the pressure gets over 1,000 PSI so that I'm not trying to make 2,250 PSI at 50 GPM! I think it's a reasonably good design. I need lots of flow to move that 6.5" Cylinder. I wish I had more especially on the return. My hydraulic tank should be larger, but...

I'll definitely add a cooler with an electronic fan. My original design had one, but when it started leaking, it got deleted rather than fixed.