Log Splitter Project

MMM · Jul 19, 2004

Check e-bay for hyd acc also. I've bought 1" QDs cheaper than NAPA 1/2". Check www.princedirect for closeouts on cyls, valves etc.

rswyan · Jul 20, 2004

My guess is that it would either blow through it or just stall - perhaps depending on what rpm the tractor is running at ...... might be exciting /forums/images/graemlins/cool.gif

In the case of a typical logsplitter, from review of the specs of 2 stage pumps, it seems the switch from low to high pressure is pretty significant - like going from 650 psi to 2500 psi (or maybe even more) and shifting down from say 11 GPM to around 3 gpm.

Basically the max output for the model of my PTO pump (an Eaton L2 series model no. 25503) is 23.6 gpm at rated rpm (2750) with a max continous pressure of 3600 psi and an intermittant pressure of 4000 psi. The specs can be found at:

Eaton Gear Pumps

However, after having said that, in reviewing the documentation that came with the backhoe, Kubota shows the pump model number as having a 2500 psi rating.

Initially, based on the Eaton documentation, I thought that some markings on the pump indicated that it was pressure limited to 2000 psi through an internal relief valve. In further reviewing the Eaton docs that does not appear to be the case - the numbers mean something else entirely - my pump doesn't appear to have an internal relief valve limiting it's pressure - apparently only flow divider pumps, which mine is not, have an internal relief valve.

A slow pass using tractor hydraulics would be similar to the second stage on a 2 stage pump - and at a similar pressure as a typical 2 stage pump that is normally used on a logsplitter would produce (about 2500 psi)

The only thing that's really missing when driving a splitter off tractor hydraulics (at least with small to mid-size CUT's that have limited hydraulic flow) is the higher flow at a lower pressure (and the faster cycle time that this would deliver) that a 2 stage pump would provide - that's why a splitter driven off this type of set up (tractor hydraulics) is slow.

rswyan · Jul 20, 2004

MMM,

Thanks - I'll check it out.

khd · Jul 20, 2004

My guess is that it would either blow through it or just stall - perhaps depending on what rpm the tractor is running at ...... might be exciting 

Your thoughts are the same as mine as long as exciting doesn't mean twisting the splitter beam or sled. Especially in a 28 or 30" splitter like you mention where you have a 4-6" running start on a 24" log. Somewhere here, I think, is a thread on a splitter withe the beam all bent. I think based on your pump I'd go with the 5" cylinder to handle to the added pressure on the full stroke.

Also: I expect the valve warning on Northern is probably a....I don't want to be responsible for....statement when someone treats the detent as an un-attended splitter and have something go wrong and an injury ensue.

Kevin

BigEddy · Jul 20, 2004

Horsepower to drive a pump is based on flow and pressure. Rule of thumb - 1HP per GPM at 1500 psi.

Given your specs, if you set your relief valve at 3000psi, you're looking at 50HP required to get that 23 GPM, but only if the pump is turning at 2750.

Assuming this is a fixed displacement pump, if you're running it at 540 on the PTO - you're only going to see 4.5GPM, but you'll still get 3000psi if the log is tough.

A 4" cylinder is going to move 24" in about 18 seconds, either direction, load or not. Roughly equivalent to an 8HP splitter, but without the fast approach and return. Run under PTO speed, and it goes slower yet.

I wouldn't worry about impact forces.

SPIKER · Jul 20, 2004

sorry I forgot to say it is HOMIER that carryies them and he is in OHIO now just left mansfield this past weekend, and heading to NEWARK ohio, not sure where exactly http://www.homier.com

here is home page, they seell the FARM-PRO tractors which are JINMA tractors which is what I have, good working gear drive for less money, but the last year prices have gone UP a good bit on them. parts stilll good price though.

Mark m
/forums/images/graemlins/laugh.gif

rswyan · Jul 20, 2004

( Your thoughts are the same as mine as long as exciting doesn't mean twisting the splitter beam or sled. Especially in a 28 or 30" splitter like you mention where you have a 4-6" running start on a 24" log. Somewhere here, I think, is a thread on a splitter withe the beam all bent. )

Yikes ! ..... I didn't mean that specifically but I envisioned some sort of hydraulic havoc ... /forums/images/graemlins/shocked.gif

I plan on using a heavy 6" x 8" I-beam so hopefully that will reduce the chances of something like that happening.

( I think based on your pump I'd go with the 5" cylinder to handle to the added pressure on the full stroke.
)

A bigger cylinder will actually equal more force generated (but it should have a slower operating speed due to the greater volume of fluid required to move the piston)

( Also: I expect the valve warning on Northern is probably a....I don't want to be responsible for....statement when someone treats the detent as an un-attended splitter and have something go wrong and an injury ensue. )

In otherwords a "CYA" statement.

rswyan · Jul 20, 2004

BigEddy,

I was looking at the performance data on the pump last night (they have charts tying the gpm output to the input HP) trying to figure out what they meant. You are correct - they show 47 HP required to achieve the rated flow and pressure of the pump.

Not having a ton of experience with hydraulics I was trying to figure out what all that meant. In my mind, it seemed to me that if the pump is supposed to produce X (pressure and output) at a specific RPM then it should produce it at that speed - regardless of whatever size tractor it was attached to. I guess the bottomline is that given a 540 RPM PTO speed there's no way one of these pumps is ever going to require the max HP - because they would never turn that fast.

( Assuming this is a fixed displacement pump, if you're running it at 540 on the PTO - you're only going to see 4.5GPM, but you'll still get 3000psi if the log is tough.
)

It is a fixed displacement pump. One thing that I think I got a little confused about was the RPM - since the pump is rated for 2750 RPM - which is the same as the max engine RPM rating on my Kubota - I erroneously assumed that the tractor engine RPM rating is what Eaton was referring to - apparently it's not - they are referring to 2750 as the pump shaft RPM. In order to get full performance from the pump it would require (in addition to a tractor with more horsepower) a transmission on the PTO shaft which took the output RPM of 540 (at PTO engine speed) and multiplied up to 2750 RPM on the pump. Is this thinking correct ?

If that's the case, I could potentially get better performance just from the tractor's own hydraulics, since their output is 6+ GPM. If all this is correct (and I think it might be) then that's kind of a bummer - and it makes me wonder why Kubota bothers to supply a PTO pump with their backhoes - probably all of the tractors they make this 'hoe for have more than adequate hydraulic specs to run it. Seems like it would be an unnecessary cost.

An 18 second extension time is way slower than what I'm looking for - I'd prefer to be under 10 seconds.

Great info - thanks.

rswyan · Jul 20, 2004

Spiker,

Thanks on the homier data - I'll scope it out.

rswyan · Jul 21, 2004

Ok, I just found this today on Surplus Center's website:

Hydraulic Cylinder

It seems to be in the size and price range (at the top) I was considering - anyone have any comments on whether there is anything about it that would make it unsuitable for use as a splitter cylinder ?

I'm unfamiliar with the SAE 6 ports, but I see I can get adapter fittings to 1/2" NPT on Surplus Center's website ....

What about the pilot load checks ?