Hydraulic Resevoirs

[kiotiken]

I built a firewood processor and I'm having a heat problem with the hydraulics. I've come to learn that the 10 gallon tank that I was sold when assembling the hydraulic components is WAY undersized. My plan is to replace the 10 gallon tank with a 37 gallon tank (37.1 GALLON HYDRAULIC RESERVOIR), but it was just suggested in my build thread (http://www.tractorbynet.com/forums/build-yourself/324028-firewood-processor-build-thread-38.html) that I consider keeping my 10 gallon tank and adding a second tank in parallel. So my question is, can I do that? I would keep the return line and filter to the 10 gallon tank as they are now, go from the outlet port on the 10 gallon tank to the return port of the new tank and have my suction line to the pump on the outlet of the new tank. Assuming that the tops of the tanks are at the same level and both tanks have breathers, will this work?

Hydraulic info for the processor:
The processor is using a 15 hp gas engine and a 28/7 GPM 2 stage pump. As mentioned above, it has a 10 gallon resevoir and has a 5" x 24" main cylinder, 24 cu hydraulic motor and 2" x 18" cylinder to adjust the splitter head. The saw is not hydraulic.

 

[2458n]

You need to do some more home work on the cooling requirements. Allowing your hyd.fluid to cool for twenty some seconds before making the trip again is not going to work. Now you have doubled the cooling tank to 20 gallons but your pump can take 27 gpm. Do you really think anything can cool in 60 seconds. And keep going hour after hour?

 

[kiotiken]

You need to do some more home work on the cooling requirements. Allowing your hyd.fluid to cool for twenty some seconds before making the trip again is not going to work. Now you have doubled the cooling tank to 20 gallons but your pump can take 27 gpm. Do you really think anything can cool in 60 seconds. And keep going hour after hour?

The second tank is 37 gallons so I'd be going from 10 gallons to 47 gallons.

 

[IceStationZebra]

I agree with 2458N. A 20 second turnover time is funtional but pushing it, 45-60 seconds would be better for air release, etc. A typical hyd tank has relatively low surface area vs volume, and is insulated with paint, so the cooling isnt that great. Really all you will be doing by adding the second tank is adding mass which will just delay the time it takes to overheat. Wild guess is that you are doubling the time it takes to overheat. If that doesn't get you enough run time you really have two options - reduce the heat generation or add a cooler w/fan. Add it before the filter so you don't blow it up when the oil is cold.

ISZ

 

[LD1]

I didn't read the build thread. How big is the pump?

General rule: 2-3 times pump flow for oil volume. If a 2-stage pump, 1x high flow. Ie: if you have a 22 GPM single stage pump, 44-66 gallon resivoir. If 22gpm 2-stage, 22 gal resivoir.

2 tanks with suction and return on same tank won't work.

 

[J_J]

I don't think today's reservoirs use the old 4 to 5 times pump flow as a gage for size.

Today's mobile hyd use about 1 to 1.5 times pump flow , and hyd radiator/fan cooling.

My machine has a 20 gal reservoir and a 45 HP engine driving three pumps with about a 20 GPM flow rate.

Check your tractor tank/reservoir and compare to pump flow.

 

[kiotiken]

I didn't read the build thread. How big is the pump?

General rule: 2-3 times pump flow for oil volume. If a 2-stage pump, 1x high flow. Ie: if you have a 22 GPM single stage pump, 44-66 gallon resivoir. If 22gpm 2-stage, 22 gal resivoir.

2 tanks with suction and return on same tank won't work.

28/7 GPM, two stage log splitter pump. I would have approx. 40 gallons of fluid if I retain my current 10 gallon tank and add a second tank or 30 gallons if I upgrade to a larger tank. Return would be to the smaller tank and suction would be from the larger tank.

I don't think today's reservoirs use the old 4 to 5 times pump flow as a gage for size.

Today's mobile hyd use about 1 to 1.5 times pump flow , and hyd radiator/fan cooling.

My machine has a 20 gal reservoir and a 45 HP engine driving three pumps with about a 20 GPM flow rate.

Check your tractor tank/reservoir and compare to pump flow.

I designed this with a logsplitter in mind, although I relied on bad advice at the store when buying the tank. This is the biggest 2 stage pump I could find but I've never seen a (commercial) logsplitter with a rad/fan for cooling. I don't have the electrical power to run a fan, it's a 15hp engine using a lawn tractor battery that wouldn't keep up to the draw of a fan. Can I use two tanks, as described above, so I'll have 40 gallons of oil will that be enough to let the oil settle and cool so the machine doesn't overheat?

 

[J_J]

Yes, that is more than enough.

16 HP is the min for that pump, so if the relief valve opens, you are at stalling point

 

[CJONE]

Tank volume either buys you time with how long it takes to heat the oil up or surface area to cool the fluid. So if you are only going to run the machine for a few hours then let it cool off a bigger res will allow you to do this. Almost everything I design and build has to be for continuous use so coolers are a must. If you can put a cooler in the air stream of the engine it will be way more effective in cost and cooling than a bigger res. I am building a power unit right now that has a 50HP Deutz diesel. It is air cooled so I am going to have to fab a bracket and shroud for the cooler, not easy but it can be done. The last splitter I built for myself had a 16hp Kawasaki liquid cooled twin, so a cooler was easy on that. CJ

 

[oldnslo]

Yes you can use two tanks as long as the line between them is large enough to prevent one from over filling or being emptied.

I would also look for the source of your heat. Do you have flow controls or flow diverters or dividers in your system? If yes these are heat generators so you have to allow for extra cooling capacity.