Splitter Hydraulics

[niemeyjt]

I have had a quick look with a tape measure

The shaft is 2" - o.d. on cylinder is 3.5".

If i.d. is 3.25", and using http://www.baumhydraulics.com/calculators/cyl_calc.htm then 3200 psi / 220 bar would give 26,500 lbs i.e. the rated 12 tonne.

J

 

[J_J]

What kind of PTO pump so you have. Is it like the Prince PTO valve?

The force depends on the pressure and the cyl in use. If your pump can not produce 3200 psi, then you can not use it in your computation. Use whatever psi the relief valve is set for. The log splutter manufactures, tend to exaggerate the capability.

 

[mmurphy]

you said the proper word here "ASSUMED" NEVER assume anything in hydraulics... what if they built the machine in the cheap and used single wire hose???? what if the they used a valve bank rated at 2500 psi??? what if they built the ram/beam to handle 13 ton???? NEVER ASSUME ANYTHING, get the FACTS then proceed.
just because SOME build them to 2500psi doesn't mean that ALL build to this

Yes you are correct, but this is a forum that most advice is given in context. Because JJ, or anyone else in this forum are not there in person to see exact information. I hope every one would realize when these guys are helping out, the OP has to do a little fact checking of there own.

 

[niemeyjt]

Well, I now have the T-piece and pressure gauge and have tested with and without the filter (which was not blocked anyway).

To recap, the cylinder is about 3.25 inches, the quoted power is 12T and the stated pressure is 220 bar (3200 psi).

I have backed off the relief valve so that it 'blows' at a lower pressure and the engine no longer stalls.

When the relief valve is blowing - at end of stroke - and there is the strange squealing noise I mentioned before, the pressure gauge shows 2200 psi - so 1000 psi too low. If I set the relief valve higher, the engine stalls.

My hypothesis is still that the pump is faulty (or has been swapped for a lower pressure one like JJ describes), it is unable to get up sufficient pressure to blow a relief valve set to 3200 psi, and stops turning stalling the engine. Lowering the relief valve pressure allows the pump to continue turning.

The dealer now says my tractor is underpowered and that is probably why the the pump wont reach 3200 psi. Given that the petrol engined version has a 6.5HP B&S, and given that I am using a 20HP Kubota, I think he does not know what he is talking about.

I am trying to get hold of the one person at the UK importers who might know, before trying to contact the manufacturers (and hoping they speak english or french as I have three words in italian).

However, any thoughts from the experts here would be welcomed.

TIA

J

 

[wvpolekat]

What RPM are you running your tractor at when it is stalling?

 

[niemeyjt]

The marked speed for 540 RPM on the PTO - approx 2700.

J

 

[rus_geek]

My hypothesis is still that the pump is faulty (or has been swapped for a lower pressure one like JJ describes), it is unable to get up sufficient pressure to blow a relief valve set to 3200 psi, and stops turning stalling the engine. Lowering the relief valve pressure allows the pump to continue turning.

The dealer now says my tractor is underpowered and that is probably why the the pump wont reach 3200 psi. Given that the petrol engined version has a 6.5HP B&S, and given that I am using a 20HP Kubota, I think he does not know what he is talking about.

I tend to agree with the dealer on this one. The 6.5HP version probably utilizes a two-stage pump. This is because the HP required to run a pump is combination of the pressure and the flow. If you can identify the specs on the pump enough to get the flow rating, you can calculate the max pressure your tractor will produce, and set the RV to that, assuming the other components will take it.

-rus-

 

[niemeyjt]

The min HP for the splitter in documentation is 12HP - and the Kubota is putting out close to 20HP (it works very well on both my mower and chipper, so I do not think tractor is blown or underpowered).

However, you are correct in saying the petrol engined version comes with a two stage pump - the parts manual shows two different parts for petrol and pto.

J