PTO Wood Splitter Questions

[OC455]

Looking at the stump grinder thread just recently, I thought about a wood splitter I saw recently and now can't find it to link the picture of it.....bah

Anyway, looking at what requirements are needed to power a splitter and I am not finding a lot of information. So, this is what I am finding with a bit of research I have been doing.

Most splitters (gas) are running between a 9 to13 GPM hydraulic pump for 20 to 30 ton rated splitters.

Most run a 4inch or 4.5inch cylinder at 24inches. 6.5 HP to 10 HP gas motors.

OK, so now here comes the fun part. The BX I have has 17.7HP at the rear PTO. The one PTO pup I found that was rated high enough (11.9 GPM) needs 27HP to get the max flow rate (2500psi) or it will only have about 1600psi with the 17.7 HP PTO. I don't know if that would be enough to push the cylinder with enough force to split any wood of a decent size.

This is the only PTO pump I have found that may have the best specs for a PTO pump: https://www.surpluscenter.com/Hydra...rince-HC-PTO-2A-PTO-Pump-540-RPM-9-1047-2.axd

Bit expensive to start out. It requires 18.1 HP to get the max 2250 psi....so it would be a bit lower on the pressure rating.

Enough to give you a headache.

 

[Nicfin36]

Have you considered a stand alone splitter instead of a tractor mounted one? I have a stand alone and it does everything I want it to. I bought it before I had either tractor, so it wasn't necessarily a choice for me on stand alone or tractor mounted.

However, I would do the same thing again. It is my understanding that a tractor splitter is a bit slower. You're putting hours on a more expensive tractor that could be put on the stand alone.

Here's a video you might find useful:

https://www.youtube.com/watch?v=jObB6caU5J4

 

[bernhardine]

Most splitters (gas) are running between a 9 to13 GPM hydraulic pump for 20 to 30 ton rated splitters.

Most run a 4inch or 4.5inch cylinder at 24inches. 6.5 HP to 10 HP gas motors.

A 4" Cylinder (inner dia), operated with max pressure of 2500 psi, has a maximum splitting power of 13,98 ton.

If you want to run it with a cycle speed of let's say 6"/s (fast midrange) in splitt direction, you need 19,54 GPM and 25 kW (34 HP) at max pressure and flow.

The speed is a very important factor. You can operate a 50 ton splitter with 1HP or less, but the coffee will be out after the first stroke

So you first should figure out, how many tons splittingpower you need, then how fast you want to work. Out of that you know how many GPM you'll need and after that you get the Power value which is necessary.

Or the other way round:
- how much PTO-power do you have at the considered PTO-speed?
- what is this speed?
- what is the minimum splitting power you need
- what is the minimum cycling speed (split direction) you want?
Out of that I can tell you if it is possible and if, which cylinder- and pump-size you'll need.

Remember, the maximum splitting power and therefore the max. PTO-HP is only needed at maximum pressure, so not very often. The output volume/speed is nearly independent of the pressure.

 

[Greg8352]

A additional consideration is the wood. We have a large number of ash trees killed by the bore. If you are in good shape you can run production with a splitting mail. Old knotty hickory requires a more serious approach.

 

[OC455]

Have you considered a stand alone splitter instead of a tractor mounted one? I have a stand alone and it does everything I want it to. I bought it before I had either tractor, so it wasn't necessarily a choice for me on stand alone or tractor mounted.

However, I would do the same thing again. It is my understanding that a tractor splitter is a bit slower. You're putting hours on a more expensive tractor that could be put on the stand alone.

Here's a video you might find useful:

https://www.youtube.com/watch?v=jObB6caU5J4

I have been using a regular old 22 ton Brave wood splitter. Most of the blocks of wood I still have on the ground are large and difficult to handle. These logs that were dropped off were from the local county and were free, so I didn't really have a choice in how big the wood was that got dropped off.

I've quartered the wood with my chainsaw (a lot of wear and tear on my saws....) or used my splitting maul to get them down to a size that is easier to handle, which still isn't easy. Aside from moving the wood I have, I am running my BX anyway to use the front end loader.

The picture I saw of the of a 3 pt splitter unit, appears that you could lift the whole unit over a piece of wood and then lower it, to split it.

 

[OC455]

A 4" Cylinder (inner dia), operated with max pressure of 2500 psi, has a maximum splitting power of 13,98 ton.

If you want to run it with a cycle speed of let's say 6"/s (fast midrange) in splitt direction, you need 19,54 GPM and 25 kW (34 HP) at max pressure and flow.

The speed is a very important factor. You can operate a 50 ton splitter with 1HP or less, but the coffee will be out after the first stroke

So you first should figure out, how many tons splittingpower you need, then how fast you want to work. Out of that you know how many GPM you'll need and after that you get the Power value which is necessary.

Or the other way round:
- how much PTO-power do you have at the considered PTO-speed?
- what is this speed?
- what is the minimum splitting power you need
- what is the minimum cycling speed (split direction) you want?
Out of that I can tell you if it is possible and if, which cylinder- and pump-size you'll need.

Remember, the maximum splitting power and therefore the max. PTO-HP is only needed at maximum pressure, so not very often. The output volume/speed is nearly independent of the pressure.

So, pretty much, the rear PTO does not have enough speed even with a correctly sized PTO hydraulic pump/HP rating to run with enough pressure to push a cylinder to split wood with enough force?

From what I can find out, most splitters are operating at or between 3000 to 3500psi. So a properly sized PTO hydraulic pump wouldn't have enough pressure to run a four inch cylinder....

I found this little calculator for log splitter speed but I don't think it would apply here: https://internationalhydraulicsus.com/logsplitter-speed-calculator

My tractor has 17.7 HP at 540 RPM at the rear PTO. I would think 22 ton would be sufficient enough to do enough of what I was thinking of. Split direction wouldn't have to be fast...10 or 15 seconds?

 

[bernhardine]

My tractor has 17.7 HP at 540 RPM at the rear PTO. I would think 22 ton would be sufficient enough to do enough of what I was thinking of. Split direction wouldn't have to be fast...10 or 15 seconds?

Ok, all we need ...

Let's say, working pressure shall be 3000 psi (207 bar). I wouldn't go higher with a DIY build.
With this, you are nearest to the 22 ton with a 4.5" Cylinder:
(sorry, I have to do it in the metric system)
4.5" are 114.3 mm dia and 57.15 mm radius
Formular is: r²*pi*p(pressure)=force
3266.12mm²*3.14*207bar= 21.22 ton

square measure of the 4.5" cyl. is 10256 mm²
As I understood you want 10 to 15 seconds for the hole stroke of 24 inches, right? Let's say 13 seconds:

24" * 25.4 mm = 609.6 mm (0.61m)
===> 10256 mm² * 609.6 mm = 6252058 mm³ (= 6.252 liter or 1.65 gal)
So, if you want these 1.65 gal in 13 seconds, the pump must deliver 7.615 GPM (28.8 liter/min)

Formular for the needed power is:

P= pressure*Volume / 510
P= 207 (bar) * 28.8 (l/min) / 510 (600*0.85) = 11.69 kW or 15.9 HP

To get that volume of 7.615 GPM at 540 rpm PTO speed you need a pump that delivers 0.05926 l/rev or 3.6 cui/rev.

 

[Nicfin36]

The picture I saw of the of a 3 pt splitter unit, appears that you could lift the whole unit over a piece of wood and then lower it, to split it.

That would be nifty. I hate dealing with giant pieces of wood. I used to fight each piece into the splitter in the vertical setting, but it is a lot of work. I usually resort to noodling them like you say you do. I have a Husqvarna 372XP that makes short work of it. But, I try to stick to smaller trees if possible. I don't burn as much wood down south, so it is easier to pick and choose my firewood.

 

[OC455]

Let's say, working pressure shall be 3000 psi (207 bar). I wouldn't go higher with a DIY build.
With this, you are nearest to the 22 ton with a 4.5" Cylinder:

So a minimum of a 7.6 GPM pump would be required. OK. What would happen if you went to a 4 inch or 101.6mm cylinder? So the radius would be 50.8mm

So: 50.8 squared x 3.14 x 207

2580.64x3.14x207=18.84 tons? Or did I screw up my math?

Looks right. So, if you went with a smaller sized cylinder, could you possibly go up from a 7.6 GPM to a higher GPM pump to compensate for the difference in the force? I don't think it works like that, but not sure.

Bernard, thanks for the insight here. Gives me a lot to think about.

 

[OC455]

That would be nifty. I hate dealing with giant pieces of wood. I used to fight each piece into the splitter in the vertical setting, but it is a lot of work. I usually resort to noodling them like you say you do. I have a Husqvarna 372XP that makes short work of it. But, I try to stick to smaller trees if possible. I don't burn as much wood down south, so it is easier to pick and choose my firewood.

Yeah, the upper end of NY, we tend to get the snow and below zero a lot, and I find that the wood furnace I have (just replaced and new double wall SS chimney) does a lot better job at keeping the house warmer than the oil furnace.

I have a Stihl 660 and 391, both saw are awesome, but trying to hog through wood length wise tends to dull out my chains and run times are longer in the end wasting gas & bar oil for me. As you've said, running a splitter verticle still takes a lot of effort to move the blocks to get split.

 

[bernhardine]

So a minimum of a 7.6 GPM pump would be required. OK. What would happen if you went to a 4 inch or 101.6mm cylinder? So the radius would be 50.8mm

So: 50.8 squared x 3.14 x 207
2580.64x3.14x207=18.84 tons?

It's 16.77 tons

If you go to a 4" cylinder, the splitting power goes down but the speed increases .

So, if you went with a smaller sized cylinder, could you possibly go up from a 7.6 GPM to a higher GPM pump to compensate for the difference in the force?

No. The force only depends on the square measureof the cylinder and the pressure.
The Volume (GPM) only has influence to the cycling speed.

 

[OC455]

It's 16.77 tons

If you go to a 4" cylinder, the splitting power goes down but the speed increases .





No. The force only depends on the square measureof the cylinder and the pressure.
The Volume (GPM) only has influence to the cycling speed.

Never been good at math....even with a calculator.

So, seeing how there is not a specific PTO pump that has the 7.6 GPM flow rate, I would either have to go up or down with the flow rate?

https://www.surpluscenter.com/Hydra...P-PTO-A-3-6-S-Hydraulic-PTO-Pump-9-8902-3.axd

https://www.surpluscenter.com/Hydra...rince-HC-PTO-7A-PTO-Pump-540-RPM-9-1047-7.axd

https://www.surpluscenter.com/Hydra...rince-HC-PTO-2A-PTO-Pump-540-RPM-9-1047-2.axd

The last pump, it would take 18.1 HP to run the pump, which would eat up power from the tractor, so it probably wouldn't be a good option.

So, a lower volume (GPM) would be a bit slower, 7.1 GPM or 7.4 GPM, instead of 7.6 GPM. Not enough to make a huge difference. The 7.4 GPM pump listed, they said it requires at least 17 HP to make it run at max psi.

 

[OC455]

Again, @bernardine thank you for the assistance. Give me a lot to go in the direction I want.

 

[North Idaho Wolfman]

You're looking at the wrong pumps...

You would run this style of pump off of a gearbox to increase RPM's.

https://www.surpluscenter.com/Hydraulics/Hydraulic-Pumps/2-Stage-Log-Splitter-Pumps/

 

[OC455]

You're looking at the wrong pumps...

You would run this style of pump off of a gearbox to increase RPM's.

https://www.surpluscenter.com/Hydraulics/Hydraulic-Pumps/2-Stage-Log-Splitter-Pumps/

Now I'm confused....

So running a PTO pump off the rear into one of these? Or running a gear box off the rear PTO into one of these?

 

[North Idaho Wolfman]

Run the pto to a 1 to 5 ratio (540 RPM in, 2700 RPM out) gearbox, or a 1 to 6 ratio (540 RPM in - 3240 RPM out) gearbox and back the throttle off so the PTO spins slower.

Then to a 2 stage Log splitter pump.

That will give you speed and power!

But I think you'll find that getting that gearbox is probably more than you could just buy a really good quality self powered portable log splitter for.

The perfect scenario is to use that pump on the mid PTO, it's the right speed for it.

 

[bernhardine]

https://www.surpluscenter.com/Hydra...P-PTO-A-3-6-S-Hydraulic-PTO-Pump-9-8902-3.axd

https://www.surpluscenter.com/Hydra...rince-HC-PTO-7A-PTO-Pump-540-RPM-9-1047-7.axd

https://www.surpluscenter.com/Hydra...rince-HC-PTO-2A-PTO-Pump-540-RPM-9-1047-2.axd

The last pump, it would take 18.1 HP to run the pump, which would eat up power from the tractor, so it probably wouldn't be a good option.

So, a lower volume (GPM) would be a bit slower, 7.1 GPM or 7.4 GPM, instead of 7.6 GPM. Not enough to make a huge difference.

These pumps are nice, because easy to install, just plugnplay. You can use them directly on the PTO-shaft of the tractor or mount them on the splitter as they are. Simple.

But have a look at the max. pressure of these pumps. It's only 2250 or 2500 psi. - So, to get up to the splitting power you want, you would need a bigger Cylinder.

The version with a 2 stage pump like NIW suggested is much more comfortable but requires more parts and a little more construction effort. A gearbox and perhaps a adaptor flange is needed and normaly you can't use it directly on the PTO-shaft of the tractor. And all together the costs are a bit higher, I guess.

So it's your choice, which pump system you want. Both will work with your tractor and no problem to calculate the size of the components you need.

There's one more point to think about: if you run the engine with perhaps only half speed, because of the use of a gearbox/2stage-pump, you won't have 17.7 HP any more. Something like 20-25% less I would guess.

 

[BAP]

Many moons ago, we had a 4 foot w tow behind wood splitter built for us by a friend who was a great welder. Originally we ran it off the remotes of one of our larger farm tractors. Then, we converted to a PTO driven pump with a reservoir tank on the splitter. We ran it with a Farmall H with no problems at all. Most of the time it was run with 1/3-1/2 throttle. The Farmall has 23-24 HP. I don’t think you will have any problems running it with your tractor. The only time you might run short would be that piece that is knotty, knarly, almost impossible to split.

 

[GreensvilleJay]

As much as I'm all for 'building and bodging', I'd buy a 20T log splitter and USE it. Life's too short to waste time making 4 trips to get the right hose, another fitting, box of bandaids, etc. Yes, I've built them, 6" bore x 24" stroke and fast. Took a LOT of pencil and paper time to get it 'right'.
Nice setup I saw was a custom, low trailer ( 4" dropped axle) with splitter mounted on the longer tongue. 'Guards' kept the splits from falling , so you just pushed then tossed them into the trailer bed. 2 jacks up front kept it stable, if tractor was needed elsewhere.

 

[RyanG]

Any reason to not just run one with a power beyond kit (Backhoe hydro)? Or if you want to mount something to the loader the 3rd function would work as well...?

I ran the Tractor supply 3pt splitter with my B3030 for a long time and loved it.

Something like this from HD
https://www.homedepot.com/p/Boss-Industrial-3Pt-22-Ton-Horizontal-Vertical-Log-Splitter-3PT22T25/304845095?mtc=Shopping-B-F_Brand-G-Multi-NA-Multi-NA-Feed-PLA-NA-NA-Catchall_PLA&cm_mmc=Shopping-B-F_Brand-G-Multi-NA-Multi-NA-Feed-PLA-NA-NA-Catchall_PLA-71700000014585962-58700001236285396-92700010802552439&gclid=Cj0KCQjw0pfzBRCOARIsANi0g0vXGrNQWiKd5Z0DgoD4oalyA3gb7z1_um_o2fdOUcUVth3_IVbewZUaAltWEALw_wcB&gclsrc=aw.ds