Gear pump vs. 2 stage splitter pump?

[SWI Don]

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

 

[George G]

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.

 

[wireedm]

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.

 

[wkpoor]

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.

 

[kevin j]

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.

 

[wireedm]

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.

 

[wireedm]

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.

 

[wkpoor]

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.

 

[wireedm]

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.

5hp and 18hp engines of similar designs likely have similar efficiencies. It's how much of each engines output that is utilized by the log splitter design and how the splitter is worked that determines how much work is done per gallon of fuel used.

It is as possible that an 18hp engine could get more work done per gallon of fuel used than a 5hp engine but the opposite is just as likely.

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.

 

[SWI Don]

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

 

[drmiller100]

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.

 

[sawfun]

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.

 

[muddstopper]

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.

 

[Whitespider]

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...

 

[Whitespider]

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.
*

 

[muddstopper]

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.

 

[ttyR2]

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.

 

[sawfun]

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.

 

[muddstopper]

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.

 

[chads]

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