# Gear pump vs. 2 stage splitter pump?



## msjanket (Mar 14, 2008)

Is it preferable to have the adequately sized gear pump or the 2 stage pump on a splitter? Some people feel the gear pumps offer certain advantages. OR, does the engine have to be really huge to power through knotty wood? thanks

Mike


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## kevin j (Mar 14, 2008)

Engine hp required to turn a pump is proportional to flow x pressure.

Two stage pumps are simply two gear sections in the same body. At low pressure both sections add together for say 11 or 16 gpm. 
Around 500 to 800 psi, the large section unloads back to the inlet, then the engine can turn the small section to 2500 psi at 3 or 4 gpm

High flow x low pressure = max engine power used.
Low flow x high pressure = max engine power used.

Running a single stage pump means you get only the small stage, say 4 gpm, through the entire cycle. SLOW. Only use the full engine hp for brief time when it went to 2500 psi. Rest of the time, low hp and slow operation.

I would not run a single stage pump even if it was free. You waste time every cycle for the next 20 years.....

k


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## kevin j (Mar 14, 2008)

forgot: powering through big knots requires force, which is pressure times cylinder size. nothing to do with engine size.

of course, bigger cylinder means slower speed, so the reason for bigger engine is to turn a larger pump and get the speed back.

k


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## drmiller100 (Mar 17, 2008)

buy the 2 stage.

run the engine at idle, and pretend you have a gear pump.

when you get bored, run the engine at WOT, and now you have 2 stage speed, and 2 stage power.

optionally. every time you cycle the 2 stage splitter, stop everything and count to 15 and pretend you have gear pump.


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## wkpoor (Mar 17, 2008)

Not all gear pumps the same says grasshopper. 
Simply put gears pumps are absolutely fantastic. Problem is you will need gobs of power to run them. My gear pump allows for a 7sec cycle time on a 26" stroke 4" cylinder. And no matter how tough the wood its always going to move at the same speed, no slowing down to 2nd stage to get through the tough ones. Drawback is the HP it takes to do that is enormous.


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## mga (Mar 18, 2008)

TreeCo said:


> The two stage pumps are gear pumps too, just two in one body. I've been running a 28gpm two stage Barnes pump for almost twenty years.




that's what i thought.

to answer the OP, two-stage pumps are like having two pumps assisting with the work load. these are ideal for splitters and why they're used most often.

also, it's common for them to be gear pumps...i don't think any other type would work for that condition.


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## triptester (Mar 18, 2008)

Two-stage pumps were designed specifically for log splitters as they are the most cost efficient. When a single stage gear pump is used the engine required to power it can cost as much as a complete splitter with a 2-stage pump.

I have only seen one splitter manufacturer that uses a single stage gear pump with a small engine. PowerSplit/TimberDevil use what they call a Drive multiplier producer between the engine and single stage pump. With this setup they claim 28 tons force and 7 second cycle times with 9 hp. engine.


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## Gologit (Mar 18, 2008)

kevin j said:


> Engine hp required to turn a pump is proportional to flow x pressure.
> 
> Two stage pumps are simply two gear sections in the same body. At low pressure both sections add together for say 11 or 16 gpm.
> Around 500 to 800 psi, the large section unloads back to the inlet, then the engine can turn the small section to 2500 psi at 3 or 4 gpm
> ...



Well said.


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## wkpoor (Mar 18, 2008)

> Running a single stage pump means you get only the small stage, say 4 gpm, through the entire cycle. SLOW. Only use the full engine hp for brief time when it went to 2500 psi. Rest of the time, low hp and slow operation.
> 
> I would not run a single stage pump even if it was free. You waste time every cycle for the next 20 years.....


I think you got it backwards. Any single stage pump is whatever the volume is which could be very high. Actually a single stage splitter will be the fastest. My single stage has a 7sec cycle time with a 26" stroke. And it is always that speed since this is no 2nd stage to slow you down. The only reason for 2 stage is purely lack of HP.


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## kevin j (Mar 18, 2008)

but that is the point: the single stage can only be as large as the engine hp will drive to whatever high pressure is selected. A 6 hp will only turn about 3 to 4 gpm at 2500 psi, so the single stage can only be the 4 gpm size.

There is not the option of picking a single stage at say 10 gpm without the engine hp to turn it. 

It is not as though it 'slows down' to the small side, but that it 'speeds up' when it can drive both stages high flow at say only 600 psi.

yes, if you have the hp to turn the single stage at say 10 gpm it will go faster. But it will go faster yet with a larger two stage of say 7-10 gpm at high presure, and still using 20+ gpm at low pressure.

Sounds like that is not an issue for your machine as faster than 7 seconds is probably not desireable. I'd guess you have maybe 20+ hp engine on 20+ gpm??


Theoretical hp is (gpm x psi) / 1714

Factoring in some efficiencies, and the formula is also easier to remember, as
(gpm x psi) / 1500 = engine hp

kcj


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## wkpoor (Mar 18, 2008)

Maybe I don't understand a 2 stage pump but I thought the 1stage was all it had and the 2nd stage was about a tenth of the first not a combined flow rate but a partial of. I at least understand a 2 stage pump is what allows small power to do big work at the price of speed.
I have tested the 2vs1 side beside and that 2nd stage just just kills productivity. Every time it shuttles down the cylinder is creeping along. Unless you have a whole pile of easy wood after a while of splitting that 2nd stage creep starts to add up to alot of wasted time. I personally would rather burn a little more fuel and giterdun than spend time watching a cylinder retract.
On the other hand the slowest splitter in the world is alot faster than an ax.


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## wkpoor (Mar 18, 2008)

I fully understand the value of the 2 stage pump. But it is what allows a small engine to split big or tough wood at the price of speed which has been my point all along here. Yes they were a great advancement in hydraulics for splitters. I'm only trying to point out I have tested the exact same cylinder and beam setup with to different modes of power. Or to say it in another way if you had to identical splitters one single stage and one 2 stage being the only difference ( provided the single stage had some more power) the single stage would out produce the 2 stage.
A friend of mine said yrs ago they had a splitter powered by a c60 International Cub engine. He said that was a fantastic unit. Quite and powerful and sipped fuel. Single stage of course but the 4 cyl engine could do the job, thats why it worked.


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## SWI Don (Mar 18, 2008)

wkpoor,

My splitter with a 28gpm two stage barnes and a 5" cylinder rarely shuttles down to low speed. It has to be a pretty knarly piece to get it to grind down and even then it will speed up once through the hard spot. My cycle times are ~ 5 sec ea way and most pieces are full speed all of the way. I did turn up the transition pressure up a bit. Not much as Cylinder Service said you will shear the input shaft if you go crazy. I run it with an 18 hp engine.

Now if i had a 40-50 hp engine I could single stage it and never kick down but my engine runs about $7-800 and the diesel at Surplus Center is just under $4000 plus radiator. Two stage 28 gpm pump is $479 and the 2.33 cu in single stage is about $315.

Now shopping around would give better deals probably on all things, I only gave $350 for my engine, but you get the general idea. A lot of guys on this board ar looking at TSC splitters, Huskey, Harbor Freight etc that aren't speed demons but they are inexpensive. As long as they don't get the opportunity to run a splitter with a fast cycle time they will not miss it. Unfortunatly they are on this board and have been exposed to several splitters with fast cycle times and some very clever designs.

Don


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## wkpoor (Mar 18, 2008)

Thanks for posting Don. You must be the guy who has been for mentioned a builder of nice fast splitters.
From my own experience I can see the 5" cylinder making the deference over the 4" in amount of shuttle time. And the 28gpm would give good cycle times too. I have posted a couple of times in saying I prefer smaller cylinders and more pressure over big cylinders. 4 1/2-5" seems to be a happy medium. What size hoses do you use on the pressure and return?
I've mentioned that the diesel is thrifty compared to gas even as much as to say my tractor uses no more than the 5.5 Briggs. An 18Vangard (which I've had on mowers...darn good engine) would probably use more.
As for putting time on a big expensive engine.... I use my tractor quite abit throughout the year even splitting wood and I only put a little over 100hrs this past yr on the engine. At that rate it will still last me 40+ yrs.


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## gary A. (Mar 19, 2008)

*I agree with wkpoor*

I have a homemade splitter that is about 12 years old and has split LOTS of wood. Lots of people borrow it and it by now has almost all the bugs worked out of it. It is a single stage pump with a 1954 wisconsin 13 horse motor on it and I will put it up against any splitter you can buy at the local farm store. It has been copied and made by 4 other people that I know of for sure. I don't know the exact pump gallonage but I seem to recall that it is about 16gpm. I have no pressure bypass and have heavy industrial hoses rated at 6000#. Way back when I built it and had a pressure gauge on it, it would easily reach 4500#. You can use all the formulas and theory you want but if I were to build another splitter I would for sure use a single stage pump. It slows down for nothing and the unloaded cycle time is the same as the loaded cycle time and for me it is about 5 seconds each direction. Only one time did I have a piece stuck on the wedge and I needed 2 come-a-longs and a sledge hammer to get the piece off. There is nothing wrong with a single stage pump. Another buddy downsized the same setup and uses a 7 or 8 gpm pump and drives it with an 8 horse briggs and it seems to work pretty well for him. I haven't used it but did help set it up.. It routinely reaches 4000# pressure for him. You cannot use farm equipment hoses rated at 2500# or else you would have hose burst problems and of course that would be way dangerous.. Get somebody that understands Hydraulic sytems to help you set it up and get the correct pump for your engine.. It is not rocket science. I know some people are going to disagree, but I would not have a 2 stage pump, even if I had to get a 4 cylinder car engine to run it because of the speed of a single stage... Just my opinion and my $ .03 worth..... gary


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## triptester (Mar 19, 2008)

Gary A.,

I would like to know the make and model of one of those single stage pumps that you are running off of small engines . I have tried several different gear and vane single stage pumps up to 11 gpm add they have all stalled a 12 hp. engine before building any decent pressure. Also where do you find duoble acting cylinders rated over 3000#. I find single acting cylinders rated to 10,000# but double acting ones rated over 3000# are very rare.


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## wkpoor (Mar 19, 2008)

> I would like to know the make and model of one of those single stage pumps that you are running off of small engines . I have tried several different gear and vane single stage pumps up to 11 gpm add they have all stalled a 12 hp. engine before building any decent pressure. Also where do you find duoble acting cylinders rated over 3000#. I find single acting cylinders rated to 10,000# but double acting ones rated over 3000# are very rare.
> triptester is online now Reply With Quote


I have run splitters like that before. Your engine becomes your relief valve as there is only so much power available for the pressure and volume it is trying to create. I personally wouldn't recommend running without a relief valve. That is the limitation and protection for your system.


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## kevin j (Mar 19, 2008)

These discussions are comparing apples and oranges though!
The key issue that is varying is engine hp.

The size of the section of pump that goes to high pressure is defined by the engine hp. One stage or two stage it does NOT matter! The small section is defined by the engine hp.

A two stage pump simply adds another section in the same body. When less than maximum psi is needed, the larger gearset adds into the flow. You get way more flow to use the entire engine hp.
BTW, I published in an earlier thread topic here I think, but a two stage pump runs the small one always to the outlet. The larger section either adds to the flow from the small one (say 3 + 8 = 11 gpm out) or it unloads back to the inlet at almost no pressure. Then the outlet is just the small one (3 gpm for instance). The pump does not vary its displacement in any way, just loads and unloads the larger section.

Sure, a single stage pump is constant speed, but the two stage is not 'slowing down' from that speed. The single stage pump STAYS on SLOW speed always, as the max size that the engine can pull. The two stage runs at the same speed in low, or speeds up when pressures are low.

My 18 hp Briggs flat twin runs a 28 gpm to 800 psi, then shifts to low for 7 gpm up to 2500 psi. 
Or I could put on a single stage pump and run 7 gpm all day, and use under 10 hp most of the time. SLOW! Or I could put on a 28 gpm single stage pump and a 45 hp engine to turn it….
Do the math and make your own decisions.

Of all the splitters I have used, my main complaint is speed, it is very rarely low force.
The only place I would ever consider using a single stage pump is if there was a free, big engine already there running say a processor or elevator, or farm tractor PTO pump package. Then you have more than enough power, so no reason to use a two stage.

But for building a machine, why would anyone put on a 30 or 40 hp engine to run 11 gpm or so, fixed at this maximum, when an 18 hp can do 28 gpm most of the day, just slowing down to 7 gpm at the tough spots?


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## gary A. (Mar 19, 2008)

triptester, I do not know the make of the cylinder, but it came off of some industrial piece of equipment. I got it from the same place I got my pump. There is a local guy who buys and rebuilds a lot of industrial equipment such as forkifts, big cranes and other stuff I don't even know what it is. The pump came off of a 10,000 pound forklift. My wife has a digital camera but I don't know much about it or I would try to get some pictures of the setup. wkpoor, you are correct that the engine is the relief valve. I didn't say it wouldn't stall the engine. But when I had a gauge on it, it would't stall until pressure was at or above 4500 pounds. The smaller pump that my buddy used got it at a local hydraulic place in Omaha. I don't remember the size exactly but seem to think it was around 6 or 7 gpm. He has a relief valve built into his directional valve and has it cranked up to around 3800-4000. I'm not saying it is the best setup or the best system, I'm just a cheap old bastard who would not buy one for over $1000 dollars back 1994 when I built this one. I already had the engine and an 8 inch beam so I stopped at the place that rebuilds industrial equipment and got the pump and cylinder for $ 200. I had wanted a smaller buzz saw for a while and put the splitter on one end and the buzz saw on the other. Total be said I probably have about $500 in it but uncounted hours of time and setup to build. It has split a ton of wood through the years and still works pretty darn good.... If you want I'll see if I can figure out the digital camera and how to load pictures on here but I am not making any promises as most of this computer stuff kicks my a&&... gary


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## triptester (Mar 19, 2008)

Gary A.,

Pics or any pump info would be great . I would like to have the option to use other pumps if I could get high enough gpm and pressures with a small engine.


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## SWI Don (Mar 19, 2008)

wkpoor,

3/4" pressure 3000 psi rated for the pressure and cylinder connections. 1" hose for the drain to tank connection, and an 1-1/2" hose for the suction. 

So far it seems to work well. I have a pressure gage and is doesn't register hardly any pressure <~100psi when operating at full speed without load. I am told that is a pretty good indicator that the hoses , valve and fittings are reasonably sized for the flow. It has probably split 15-20 cord or so over the last two seasons, maybe more, without issue. 

I need to get it finished with the log lift, hydraulic 4-way and offload table but time seems to stand in my way.

Don


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## George G (Mar 20, 2008)

Gary A must be running with a little vodoo. It would take about 100hp(gas engine) to run a 16gpm single stage pump at 4500psi. As far as a cylinder holding up to that kind of psi, It might. Most cylinders are rated with a 4 to 1 safety factor. To get a cylinder that is rated for that kind of psi is going to cost ya. We had a couple of machines that run at 5200psi. The cylinders were 5"bore and 30" stroke with a 4"dia rod. Somehow they broke the rod on a cylinder one time. The rod caught the rod packing gland and ripped it right out the end of the cylinder. We had to replace the cylinder. The cylinder weighs a little over 1100lbs, new cylinder cost $13000.00 , amount of fun installing .. priceless.


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## wireedm (Mar 20, 2008)

Just get the two stage pump. 

The little time the pump needs to go into the second stage does not justify the gas consumption and cost of the engine that would need to be at least double the hp. When the pump goes into the second stage its usually only for a few seconds. Once the stubborn log is cracked open the pump goes right back into high gear. At the end of a day you may have what, a total of 5-10 minutes in low gear? That's a no brainer. 

How many tanks of gas would a 12hp engine go through a day verses a 5hp, even at no load?

If you want speed, get a 4" cylinder with a 28gpm pump and at least 12hp. Just get out of the way! You'll have a 5-6 second cycle time on a 24" stroke. Then, you could justify the difference in engine size because you'll only be using the engine half of the time, only if you have at least two people loading. One person couldn't keep up with cutting double the wood in the same time.


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## wkpoor (Mar 20, 2008)

wireedm, I agree with your post mostly but I've actually done the test. We ran 2 identical splitters side be side in the same pile of curly red elm ( major tough wood to split) and the single stage unit will outpace the 2stage unit 2-1. More time is spent in 2nd stage than you realize. Now this was 4" cylinders. Obviously bigger cylinder may have totally different results. 

I agree though the best setup for most people is the 28GPM 2 stage with about 12-18 HP twin.


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## kevin j (Mar 20, 2008)

folks, if the pump is sized to the engine, 'low gear' is NOT slowing down, it is the maximum hp the engine can pull. High speed at lower pressure is a SPEEDUP from there, so what you get is a bonus.

a single stage is IN this 'low gear' ALL the time

so with all due respect your identical splitters were not identical. One had a much bigger engine. Or else one had a pump way udnersized from what the engine could pull.

Then, if you have a bigger engine anyway, may as well get even MORE speed with a two stage.


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## wireedm (Mar 20, 2008)

wkpoor said:


> wireedm, I agree with your post mostly but I've actually done the test. We ran 2 identical splitters side be side in the same pile of curly red elm ( major tough wood to split) and the single stage unit will outpace the 2stage unit 2-1. More time is spent in 2nd stage than you realize. Now this was 4" cylinders. Obviously bigger cylinder may have totally different results.
> 
> I agree though the best setup for most people is the 28GPM 2 stage with about 12-18 HP twin.



The bottom line could very well be the type of wood that you split MOST of the time. I am usually splitting oak here in W. North Carolina which splits easily once the knots are cracked open. If there isn't a knot, its much like poplar except for a few fibers that can be a pain.


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## wireedm (Mar 20, 2008)

TreeCo said:


> Is that a typo?



Nope. It's kinda like my big Husky. It'll guzzle a tank of gas in about an hour, whereas my little saw sips much longer. (Although after 45 minutes to an hour with a big saw, you're ready to set it down for a rest.)

Could displacement be the reason a scooter gets 70mpg?

Same thing with a 12hp-18hp verses a 5hp. The little engine WILL get better life out of a tank of fuel.


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## wkpoor (Mar 20, 2008)

> Your single stage/giant engine Vs. 2 stage/smaller engine comparison just does not compute.


I can idle the engine so the ram speed unloaded is the same.
My neighbor commented just the other day how he noticed after running mine and going back to his how much his splitter was in 2nd stage. Its something you wouldn't notice unless you where running them back to back. We have been splitting on the same big pile for over a week now. Sometimes with my unit sometimes with his. And man I thought that diesel was noisy but after a while right next to that screaming Briggs the Diesel wasn't so bad. The quietest power was the Allis CA. It was almost pleasant it was so quite.


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## wireedm (Mar 20, 2008)

TreeCo said:


> Thanks for clarifying.
> 
> I agree with you on the smaller engine (5hp) Vs. and 18 hp engine lasting longer on a tank of fuel but the total amount of work actually being done enters the equation somewhere.
> 
> ...



I certainly agree. It is much harder for one person to load wood twice as fast to keep an 18hp engine under a load. At the end of the day, you're glad you have any size engine and hydraulic cylinder over a go-devil.


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## SWI Don (Mar 20, 2008)

Using a 5" cylinder my splitter will split most anything, red elm, chinese elm, walnut included under 500 psi. Now the nasty crotches will kick it down for a moment but unless I am shearing 8" inches of wood it pops and speeds back up.

Now with a 4" cylinder 12.56 in^2 vs 19.625 in^2 would require 1.56 times the pressure to do the same thing = ~781 psi which is above the kickdown pressure unless it has been adjusted up. So a person running a 4" splitter will see a lot more slow speed in tough wood with a two stage pump. This correlates with wkpoor's observations.

Don


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## drmiller100 (Mar 22, 2008)

my experience with wood is the ram goes really fast into the wood, then kicks down for about 2 inches to "break" the wood, then goes back to high speed the rest of the way in and the rest of the way out.


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## sawfun (Sep 5, 2014)

I have a 4 cylinder 1600cc Pinto engine powered splitter I bought used for $1500 it runs a single stage pump (unknown gpm) 5" cylinder 2" ram 24" stroke and will run that in 5.5 seconds empty or with an easy split, like 15" wood, at 600 rpm. Nice and quiet compared to 1 cylinder air cooled engines. 6 second speed when cutting 24" elm on end through a 6" knot. But that is at 1300 rpm. The hydraulic tank is 7 gallons and the fluid stays plenty cool. Yes it eats fuel but not that much more than a two cylinder Vanguard I suspect.


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## muddstopper (Sep 5, 2014)

It doesnt take anymore hp to run a single stage pump than it does to run a 2 stage pump of the same flow and pressure. How much hp is needed is determined by the actual pressure output. A cylinder just running over a beam under noload will not require tons of pressure and therefore the amount of hp to pull the pump would be very low. Once you put a load on the cylinder, then the pump starts to build pressure and this is where engine size comes into play. I run a 5in cyl, 28gpm 2 stage pump with a 25hp kholer engine. Before purchaseing the 2stage pump, I had a 14gpm single stage vane pump on the splitter. All things equal, the 14gpm single stage pump would product more splits per hr than the 28gpm 2stage pump I now have on the same splitter. Its hard to bog a 25hp engine splitting wood, so I seldom see the engine labor having to pull either pump. The exception is with the big croches and knotty pieces. When before with the single stage pump, I would notice the engine slightly bog or slow down, but the cylinder speed difference was almost unnoticed. With the 2 stage pump, the engine doesnt bog, but there is a noticeable slow down of the cylinder speed. But this is where all things are not so equal any more. With the 2stage pump, as pressure builds, it kicks down to a lower flow rate. Lower flow, lower hp and slower speed. If you dot have the hp to pull a high flow pump at high pressure, its only logical that one would choose a 2 stage pump and suffer thru the reduced splitting speed during the time the pump is in low flow high pressure mode. This slow speed only last for a second or two. If you have the hp to pull a high flow single stage pump, then it will always produce more splits perhr than the same engine on the same splitter using 2 stage pump. It doesnt take as much power to split wood as some folks think. Sure there will always be times when you wish you had more power, but if you are splitting small dia rounds you could probably be just as well off with a 5hp, 3in cyl splitter instead of a 30ton model. My wood is usually large dia, with plenty of knots and i have stuck the 6way wedge being pushed with a 5in cylinder. My next splitter build will have two 5in cylinders and a 60gpm single stage pump.


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## Whitespider (Sep 6, 2014)

I read these splitter threads and am always amazed... what can and can't be done, how big cylinders and engines need to be, etc., etc., etc.
Y'all are thinking inside the box.

My splitter uses a small gear pump (about the size of my fist), driven by a 7 HP Tecumseh. The pressure line running from pump-to-control valve has an outside diameter smaller than my pinky finger. The outside diameter of the cylinder is well under 3 inches. The control valve does not have a pressure bypass... and Log Boss claims 8000 PSI operating pressure. Off-load cycle time for the 25 inch stroke is less than 10 seconds. Ram force is rated at 18 ton (15 ton for the 5 HP model)... but that 18 ton rating is continuous, not "peak" like the box store splitters. Meaning, the 18 ton Log Boss is comparable to a 22-25 ton box store splitter, yet uses much smaller components and weighs under 200 pounds.

Even though it has a gear pump, the thing will still "shift gears"... but it ain't accomplished in the pump. Log Boss uses an (exclusive and patented) "oil to oil piston booster" (whatever that is). The "shifting" is accomplished by a "load sensor" in the control valve... light duty splitting runs at 5 ton, but as the load increases so does the tonnage, up to the full 18 ton. It don't just snap into "second stage" like a two-stage pump, it's a variable thing allowing the ram to run at the fastest speed possible for the current load.

Because the thing has automatic throttle control it always returns to idle when the ram is at rest... meaning you can split most of the day on a couple gallons gas. The fully hands-free auto-cycle means you're never standing there wasting time holding on to a lever. And at something less than 200 pounds, you can roll it around with one hand... you're never moving rounds to the splitter, you move the splitter to the rounds. Heck, my 6-year-old can pick up the wedge end and roll it around.

It's availible with high-speed hub/wheels/tires if a fella' really wants them... but I can load it into a pickup myself (shrug).
And they don't cost any more than a box store splitter does...


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## Whitespider (Sep 6, 2014)

Oh yeah, I forgot...
The stroke length is infinitely adjustable via a simple thumb screw... meaning the auto-cycle only uses the amount of ram required, reducing cycle time even more.
*


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## muddstopper (Sep 6, 2014)

Give you $100 for it. If you werent so far away, I might offer a little bit more. I think that machine would make an excellent addition to my big splitter for doing resplits. It would never make it as my main splitter, but should work great for some of the smaller stuff. The small stuff is actually kind of aggravating on a machine with a 6way blade. Even tho the blade is adjustable, I end up with to many splinters.


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## ttyR2 (Sep 6, 2014)

A good used diesel VW Rabbit engine would be a good candidate for a large splitter engine. 52HP in the non-turbo 1600cc variant, I believe.


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## sawfun (Sep 6, 2014)

That VW diesel has about 25 less horsepower than my Pinto engine but is way, way, better on fuel. Although that Pinto 1600 isn't bad as it splits most stuff at 600 rpm vs 1800 + rpm for the single cylinders.


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## muddstopper (Sep 7, 2014)

I have a 51hp Iszuzu diesel engine I was going to use to build a firewood processor. Would have worked pretty good If i had stuck to original plans. Now I am looking for a 4bt cummins to get the 100 or so hp I will need to make everything work the way I want it to. The 51hp diesel will still work, but I wouldnt be able to run everything at the same time and that would slow down the whole operation.


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## chads (Sep 7, 2014)

If you look at pump specs one thing to keep in mind is rpm.
A PTO pump will run 540 or 1000 rpm depending on what your tractor has unless you use chain or belt drive to speed it up.
Running at 3600 rpm is painful on the ears etc. if your running a small motor.
Think of a generator and how loud they are.
Lets face it no one wants to be around a loud splitter,I would like to have a big electric one no I think of it.

I am working on a tractor and according to plan the new pump puts out 5-7 or so gpm at 1500 rpm, its single stage.
It will take a bit of HP but should be nice for a loader or even a splitter.
I can speed it up to around 2800-3000 rpm to get 12 gpm by using the throttle.
The cost of larger pumps is not much different than the smaller ones as long as you can pull it.

I once bought a splitter that didn't work I had a 13 hp Honda on hand and put it on there and geared it up with larger pulley it so it ran about 1/2 throttle worked great and easy to be around.
Unfortunately I sold it but it was really nice.

The key is to match up desired rpm to desired output to hp available.
Any item can be changed in this equation depending on $ or what you have on hand. 
Chad


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## Justin Erlewine (May 7, 2019)

Hey guys . New in here but have been following your posts. I have an old splitter that needs some love. The cylinder and the pump are shot. I don't know how to go about rebuilding them due to their are no numbers left on either of them. I happen to have a 21 GPM single stage bi directional pump lying around. The problem with that is from what I have gathered you guys say single stage is not the way to go. Still working on getting another Cylinder and was holding off on that until I know what to do with the pump. Is this pump even worth wasting my time?


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## sawfun (May 7, 2019)

Justin Erlewine said:


> Hey guy . New in here but have been following your posts. I have an old splitter that needs some love. The cylinder and the pump are shot. I don't know how to go about rebuilding them due to their are no numbers left on either of them. I happen to have a 21 GPM single stage bi directional pump lying around. The problem with that is from what I have gathered you guys say single stage is not the way to go. Still working on getting another Cylinder and was holding off on that until I know what to do with the pump. Is this pump even worth wasting my time?


If you have enough power single stage requires a lot less oil and stays relatively cool. I have one on my splitter, (not sure of the output) but I'm running a 75 hp 1600cc Pinto engine. It pushes a 5" × 24" cylinder very well. Most splitting is done at 500 rpm with low pressure and 9 seconds. I can gain 3 seconds with more rpm but prefer the quiet low noise of it working at idle.


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## kevin j (May 7, 2019)

two stage. 
unless very unusual circumstances i would not consider single pump even if free

21 gpm at 3000 psi is about 40 hp.


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## Justin Erlewine (May 7, 2019)

The old pump has a pulley system Large drive pulley coming off the motor and small 2.5" on the pump. Why I dont know. Im betting they tried to get more out of the old pump and ended up being its demise. A 21gpm single stage should push about half its potential at about 500-1000rpm shouldnt it? The pulleys basically act like a gear reduction anyway. If I switched the pulleys so the pump is running at lower rpm than the motor puts out do you think it would still be productive?


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## kevin j (May 7, 2019)

gear pumps are in the class of fixed displacement pumps. That means they push out a certain fixed flow volume (not pressure) for every revolution of the shaft. It’s typically rated in cubic inches per revolution. 
cubic inches per revolution, times the number of revolutions per minute, divided by 231 in.³ per gallon will tell you how many gallons per minute of output flow. 

So when it’s 21 gallons pump that has to be specified at some RPM. Then when the RPM and gallons is known the flow is roughly proportional to speed. if you cut the speed in half you’ll have about half of the flow.
the new reduced flow times the pressure will give you a reduced horsepower required to drive pump. 

(psi x gpm) / 1714 = hp

and easier to remember rule of thumb that includes inefficiencies things like that is (psi times gallons per minute )divided by 1500 equals horsepower fairly closely. 

most pumps are not rated for chain or v belt drive because the tension puts a side load on the front bearing. That’s probably what destroyed your pump eventually. Most pumps are designed for torsional only with the shaft coupling only or they have an optional heavy duty bearing in the front section


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## kevin j (May 7, 2019)

also, if you slow the pump down with v belt, the flow drops off. So now you have a 10 gpm (or whatever) pump that still takes 20 hp to drive to full pressure. Way better to have a 28 gpm pump on high speed, then 5 gpm at high pressure, on that same 15-20 hp engine.

might be some issues with driving 20 hp in a v belt, depending on pulley sizexs. Larger pulleys transmit more torque. Might need two belts. then the belt tyension is side overhung load on the bearings again.

If you have to replace cylinder, and pump, I’d look carefully at the engine first, and the beam. Is it worth using the beam and slider, wedge, etc and putting money into it? what size and shape is the engine? What shape and design are the hydr tank, filter, etc?

I would more likely just buy a used 4 inch splitter, typical 5 hp and 11 or 13 gpm pump. Then either run it as is, or if you get impatient with speed, change the cylinder to 3 inch to get serious speed. Search for my post on the 3 inch, 20 stroke, folding splitter. 4.5 hp, 3 seconds out and 3 seconds back.


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