When my log splitter piston gets very hot....

[crowbait]

It would seem to me that the higher the tonnage of a log splitter, that the hotter it will get. No? I would think that as the pressure goes up, you're asking the hydraulic oil to do more work, and thus more heat is generated. Is this true?

 

[BC_Logger]

more pressure, more oil, more heat

the more oil you cycle more heat will be transfered

 

[crowbait]

So, the best way to reduce the heat, is to increase your tank size, thus giving your oil more "surface area" for cooling....yes?

 

[Dadatwins]

Increased tank size and the right oil for the tank. Hydro oil has different grades like engine oil, use the cheap stuff and you will have problems.

 

[mga]

....but......but it's all in the design. I have a 45 gallon hydraulic tank on my splitter.....and it stays cool.

45 gallon????

gees...i complained about filling my 18 gallon tank!!

 

[Frank Boyer]

It would seem to me that the higher the tonnage of a log splitter, that the hotter it will get. No? I would think that as the pressure goes up, you're asking the hydraulic oil to do more work, and thus more heat is generated. Is this true?

Most splitters run in the 2200-2500 psi range. The extra power comes from a larger ram. As the pump/motor size goes up the line size and reservoir size go up. A well designed system should not have a problem.

 

[drmiller100]

actually the heat COMES from inefficiencies.

so, lets say at peak pressure your pump is 85 percent efficient.
that means 15 percent of the power is covnerted to heat at peak pressure.

at lower pressures, efficiencies almost always go up. larger tank means more heat transfer, more mass, less ultimate peak temperature.

 

[sawinredneck]

But a well designed Bobcat, can flow 18gpm with a 22 gallon hyd. res., how is that? And, the Hydrostat system never runs back to the resovoir? Want to talk about flow now?

Again, I must be stupid.

Yes, more fluid helps, but desining the system right, helps most.

 

[STEELHEAD]

talkin about flow

On most all hydrostatic drives , like bobcat, a portion of the oil goes back to the tank , for filtering and cooling, almost ALL commercial hydraulic units are fitted with oil coolers like the bobcat.

 

[SmokinDodge]

It would seem to me that the higher the tonnage of a log splitter, that the hotter it will get. No? I would think that as the pressure goes up, you're asking the hydraulic oil to do more work, and thus more heat is generated. Is this true?

It all has to do with surface area of the piston in the ram. A 25 ton splitter runs at the same pressure as a 30 ton (generally speaking) but the larger diameter of the piston allows for more splitting pressure with the same hyd system pressure.
The formula for figureing tonnage is Force=Pressure x Area, if you increase the area the fluid has to act on you will net a higher tonnage.

 

[leon]

It would seem to me that the higher the tonnage of a log splitter, that the hotter it will get. No? I would think that as the pressure goes up, you're asking the hydraulic oil to do more work, and thus more heat is generated. Is this true?

A machines duty cycle and seasonal temperature norms determines oil operating temperature. The more it is used the hotter it will become and hence the more efficient.

When hydraulic oil becomes cold it becomes more dense and is very difficult to pump-with a lot of processors the pump is directly driven off the flywheel and, one its an easy installation and, two it is harder to start an engine without a Rockford or other type of power take off.

Big engine starters have huge amperage and huge cold cranking amp batteries either in series for a larger voltage or parallel for higher cold cranking amperage as a rule.

Hydraulic oils have varying capacity at various temperature-the lower the viscosity of hydraulic oils the greater the heat transfer and the more efficient the oil is at delivering pressure and force to the cylinders of a processor or log splitter.

This is why they want you to warm up machines before using them- me I use a salamander to heat up my log splitter when the weather gets cold-it runs so much better after a warm up like that.

The hotter the hydraulic oils is = maximum operating temperature the more efficiently it delivers total hydraulic power/force at its maximum.

Bobcats have Cessna closed center bent axial hydraulic piston pumps which are the most efficient and deliver the most power in a small package at the time of delivery.

Gear pumps are the least costly and the lowest efficient method of delivering hydraulic pressure, vane pumps are the next most efficient and deliver better cold weather performance simply from its design and then the top of the line pump is the piston pump which is either the bent axial pump or inline piston pump.

A good hydraulic oil for any weather is a ten weight hydraulic oil. engine heaters do wonders for hydraulic oil systems as the heat is transfered indirectly via the metal components in the engine.

 

[sawinredneck]

On most all hydrostatic drives , like bobcat, a portion of the oil goes back to the tank , for filtering and cooling, almost ALL commercial hydraulic units are fitted with oil coolers like the bobcat.

Hence "well desinged"!

 

[triptester]

Proper design of the system is very important when trying to control heat build-up. My brother had a splitter with a single stage 7 gpm pump and 20 gallon reservoir. After 2 hours of use the tank would be uncomfortably warm to the touch by simply changing the hoses and type of fittings used the temperature dropped to barely warming the tank.

He found that the fittings greatly restricted the flow causing the heat build-up.

 

[leon]

oil oil every where

Proper design of the system is very important when trying to control heat build-up. My brother had a splitter with a single stage 7 gpm pump and 20 gallon reservoir. After 2 hours of use the tank would be uncomfortably warm to the touch by simply changing the hoses and type of fittings used the temperature dropped to barely warming the tank.

He found that the fittings greatly restricted the flow causing the heat build-up.

I would be willing to bet he had a herd of regular 90 degree fittings plumbed into the tank rather than sweep 90 degree gooseneck fittings. he may have had a collapsed hose or two as well as rubber hose is famous for that due to the inner rubber tube which is surrounded by the wire reinforcement-did he change both the pressure and suction lines to the valve body?

 

[mga]

a good web site for hydraulic information. you can sign up for a free weekly letter and/or search the data banks for alot of info:

http://www.insidersecretstohydraulics.com/?Hydraulic+fitting

 

[triptester]

I would be willing to bet he had a herd of regular 90 degree fittings plumbed into the tank rather than sweep 90 degree gooseneck fittings. he may have had a collapsed hose or two as well as rubber hose is famous for that due to the inner rubber tube which is surrounded by the wire reinforcement-did he change both the pressure and suction lines to the valve body?

The original fittings were JIC bent tube 90's on the pressure side . After close inspection he found the fittings had 1/8 inch smaller I.D. than the hose. The only change made was new high pressure hose and fittings.

 

[leon]

The original fittings were JIC bent tube 90's on the pressure side . After close inspection he found the fittings had 1/8 inch smaller I.D. than the hose. The only change made was new high pressure hose and fittings.

They must have been single wire braid then as a double wire braid hose fitting would not deform like that unless it was a hydraulic press on fitting that was damaged/swaged improperly- was there a ridge along the top of the old fittings?-this would be a definite indicator of a bad hose job.

:chainsawguy:

 

[triptester]

I dug through my collection of hydraulic fittings and compared the inside diameter of the fittings. For 1/2" hose fittings with a NPT or strait thread the I.D. was 7/16" while the JIC flare fittings had only 5/16 I.D. . This restriction between pump and control valve will effect heat build-up greatly. Other locations should not be as greatly effected.

Another major cause of heat is cavitation when air is added to the fluid by just dumping it into the reservoir with the return line rather than keeping the return submerged.

 

[Al Smith]

In addition to what has already been mentioned,a cylinder that is bypassing will get hot enough to fry an egg on,ouch.Type A,tranny fluid, is about the best for usage in most hydraulic systems used for wide variations of ambiant temperatures.In addition,a smaller cylinder has tendency to get a lot more heat generated than a larger cylinder applying the same tonnage force.

The working side of the cylinder is only going to be under whatever amount of pressure it needs to move it through the wood.Obviously it would require a lot more pressure to move a 3.5" through a big gnarly chunk of oak that it would for a 5" cylinder.

Another often overlooked item is hose or line sizes restricting flow.A 3/4" line has twice the area of a 1/2" line and a 1" has 4 times the area.What has already been mentioned about 90 degree fittings holds very true.It takes a lot more effort to shove oil around a turn than pushing it straight.In the design of most industrial hydraulic applications,the steel lines are bend rarther the use of fittings are kept to a minimum.These are open center systems,in other words the lines are always under pressure with the relief usually in the bypass condition.

More times than not these systems use large lines and large cylinders rated at 3,000 lbs or over but ran at around 800 psi.Running at this lower pressure increases the life of the components by about 10 fold.

 

[Al Smith]

While this discussion is still going on another thing popped into my pea brain.Often times the wear plates and gears,pump bodies of gear pumps get worn to the point the pump internally bypasses.The vains can also become worn in vain pumps and the pistons and squish plates become won on Vickers piston pumps.

No pump is 100 percent efficient but some more so than others.If and when a pump bypasses internally it has the same effect as a cylinder bypassing in that heat will be generated into the fliud,it has no other place to go.By and large the pumps used on most splitters are not rebuildable.The only cure ,if the pump is bypassing is to replace it,that being the case.