How hot should Hydraulic cylinder get?

[ctgoldwing]

I split about 2 rick of wood today on my log splitter. Logs were all huge and pump was in low volume/high pressure mode most of the time. Cylinder was very warm to touch. Not so hot you could not hold your hand to it, but very warm. I would guess about 140 degrees. Is this to hot? I have a 10 gallon tank and have never felt it this warm before. Usually, I split when it is much cooler outside. It was near 80 degrees today.

The touch method can be deceiving:

"A safe temperature for hot water is 110ｰ F, which exposure to results in third degree burns in approximately ten hours.3 Even though this is a 'relatively-safe' temperature, exposure to water set at 110ｰ F is painful; the human pain threshold is around 106-108ｰ F."

" An approximate one-second exposure to 160ｰ F water will result in third degree burns.1 Where the water is 130ｰ F, an approximate half-minute exposure will result in third degree burns"

 

[J_J]

Hydraulic Technical Information: Oil

 

[Inky05]

...aclimatized...

Where's my dictionary????

 

[Grateful11]

I did a search and found this thread.

We ran our new L3940 HST pretty had yesterday, using the FEL for about 3-4 hours and noticed that when I touched
the loader cylinders you couldn't leave your hand on them for more than about 2-4 seconds. How does that sound, I
have no idea what the temp. of the cylinders were. I've never paid attention to the temp. of the cylinders of our other
loader on a IH 574. I just happen to lean on one and noticed it was pretty warm.

 

[gpflepsen]

The two types of heat created in splitters are the heat of compression and frictional heat.
The heat of compression is the "work" being done by the cylinder.

I'd like someone to expand on this concept. How is the cylinder doing (absorbing) work and making heat, other that if it is bypassing oil through a leaking seal. The cylinder is doing no work, it is a balance of forces, psi*area and rod reaction. The pump does the work (dP*gpm) and the system absorbs the work as heat (pressure losses*gpm) and splits wood (force*distance).

I just don"t get the heat of compression concept in the cylinder, being that it is a solid fluid system.

 

[AKKAMAAN]

I'd like someone to expand on this concept. How is the cylinder doing (absorbing) work and making heat, other that if it is bypassing oil through a leaking seal. The cylinder is doing no work, it is a balance of forces, psi*area and rod reaction. The pump does the work (dP*gpm) and the system absorbs the work as heat (pressure losses*gpm) and splits wood (force*distance).

I just don"t get the heat of compression concept in the cylinder, being that it is a solid fluid system.

You are right, compression is not a main factor that heats up oil, even though oil can compress about 1% at a few thousand psi....air content in oil can make it compress more....usually internal leakage in pump or cylinder, restricted flow in lines and valves, not to forget backpressure in return lines or flow bypasses in relief valves or control valves....

 

[RickB]

I'd like someone to expand on this concept.
I just don"t get the heat of compression concept in the cylinder, being that it is a solid fluid system.

Compressing any fliud causes it to heat. Basic physics 101. Compressing fluids and squeezing them through small spaces heats them more.

What the heck is a "solid fluid system"???????

 

[Redneck in training]

Even solids heat up when compressed. Hit a piece of steel with a hammer. It will get hot.
Take a rubber string, strech it fast and put it on your lips. It will feel cold. Keep it stretched until it reaches ambient temperature, then release the tension and put it on your lips. It will feel hot.

 

[jinman]

Cylinder was very warm to touch. Not so hot you could not hold your hand to it, but very warm. I would guess about 140 degrees. Is this to hot?

Most home water heaters are set below 140 degrees and you cannot hold your hand under the water. My guess is your cylinder's temperature was far below 140 degrees. That said, my car regularly gets up to 140 degrees inside during the summer while sitting in the sun with the windows up. 140 degrees for a hydraulic system is a "walk in the park."

 

[AKKAMAAN]

"Heat" is a very relative term!! Cold too!!
"Heat" is a strong term, and usually not a god word to use for describing increased temperature, because it is RELATIVE....

Actually, straight physically, there is nothing like cold, according to William Thomson, 1st baron kelvin, that discovered the absolut temperature scale.

Thomson found out that at a certain lowest material temperture, there is a theoretical absence of all thermal energy. No molecular activity. That temperature is about minus 273 C, or minus 460F...He gave that lowest temperature Zero, on his own scale called KELVIN, which is also the official international system scale for temperature......plus 273K=0C=32F....

Hammering metal or stretching rubberbands etc, is molecular stress or molecular movement, that causes friction. So is pouring fluid out of a bottle. And from friction we get "heat", or better, INCREASED TEMPERATURE.

So by forcing material to deform, pour, flow, change volume, etc, we transfer some work energy into increased temperature ("heat") in that piece of material....That happens around everything that moves....

Pressureize oil in a hose, wont create any "heat", maybe some 0.1 or 0.01 of a degree temperature raise. But if we force that oil to move, there will be friction, and that will be a "heat"-factor of importance....the more we restrict flow, the higher pressure is needed to maintain flow, and the higher temperature increase we get.....Broken piston seal, leaking relief valve, worned out pump, clogged return filter, elbow fittings, undersized hoses etc etc.