a different log splitter

IanM · Mar 6, 2006

I discovered this forum a few days ago and have been very impressed with the wealth of information. It gave me a crash course on log splitters and now I just have to build one of my own.

The best type for my situation will be 3ph with power coming from the hydraulics of my L2550. It's my vineyard tractor and I love it, but its hydraulic pump only puts out 7.9 gpm and as I want to run at a fast idle with a 4 x 24 or even 4.5 x 24 cylinder I know things will be slow. Maybe very slow. To speed things up I plan on building a splitter that splits on both strokes. Anyone out there built one that way? I've been studying the Case and Spitfire models from photos and have come up with a couple of different possible designs.

One would be to use a 6 foot length of 6x8 tubing, either 3/8 or 1/2 inch and have the cylinder mounted inside like the Spitfire model. I would use a section of modified I or H beam, or possibly tubing, as the carrier and make it longer than 6 inches to lessen binding. Not quite sure what would work best in that situation. The tubing would have to have a 1 inch by 24 inch section cut out right down the middle of the top to one end to facilitate a piece of plate to attach the splitting head to. Also, tubing tends to be expensive and I don't happen to have a 6 foot section of it in my bone pile at the moment.

Another possibility would be to use two 2 x 24 cylinders or something similar mounted as high as possible on each side of a 6x8 or 8x8 H beam with the carrier riding on top like is more common. This would mean a little more plumbing. Would there be significant loss of power this way?
All else being equal, I assume two 2 in cylinders provide approximately the same force as one 4 in.

I have modest welding skills but more importantly a friend who is really good at it to help me out when I'm in over my head.

Any thoughts? Are there other things I should be considering? I want to fix on a final design and start collecting parts. This will be a long process as I'm a grape farmer by trade and my busy season is approaching, but I hope to have a splitter working by this fall.

Ian

D80 · Mar 6, 2006

ACTUALLY THE ONE 4" CYLINDER WILL HAVE ABOUT TWICE AS MUCH FORCE AS TWO 2" CYLINDERS.

MadDog · Mar 6, 2006

D80 is dead-on right, but it might be helpful to you to know why. Splitting force is the product of pressure (psi) times the area over which it is exerted. Because the area of any cylinder is derived by the formula a= Pi times r squared, when r=1 a= approx. 3.1416 and thus the area of two 2" cylinders (each 1" radius) = approx. 6.2832.

However, the radius of a 4" cylinder is 2" and thus the area= 4xPi or 12.566. It is squaring the radius that results in the geometric multiplication of splitting force as cylinder diameter increases.

If you plan to operate at, say, 2500 psi, the difference is between a roughly 8 ton and 16 (31,415#) ton machine. Interestingly, if you went from a 4" to just a 4.5" cylinder, the 1/2" greater diam (a 12.5% increase) would yield an increase to 39,760# or almost a 20 ton ram force (almost a 26.5% increase in force).

BTW, I am presently building a splitter with a 5" cylinder.

Also, you might want to consider using your rear pto to run a separate pump, rather than using the tractor's hydraulics. Near as I can figure your L2250 has between 20 and 22 pto hp (depending on type of transmission) and that is plenty to run a 2 stage pump generating 22 (or even the larger Barnes 2-stage generating 28) gpm. That would give you pretty good cycle times even using a 4", 4.5" or 5" cylinder. ..just a thought.

Hope some of this helps. If you want to know any further details on the splitter I am building (for use with a B7800, putting out 22 pto hp) I started a thread on it, or feel free to PM me.

IanM · Mar 6, 2006

Thanks for the responses. Now that I understand the math a bit better I'll go back and reconsider my design.

Maddog-I have read the thread on your splitter several times and have learned a lot from it. You're going to have a dynamite piece of equipment when your done. As for the pto approach, I just assumed it would cost too much but you've got me thinking and I'll spend this rainy afternoon checking out the prices of pumps and other componets. My L2550GST has a listed pto hp of 23.5. Would it run a two stage pump at an adequate flow to operate a 4.5 or 5 cylinder at relatively low engine rpm? Say 1200 or less?

Ian

cp1969 · Mar 6, 2006

Another thing to consider for a split-both-directions splitter is that the ram is not equally strong in both directions.

I vote for getting a PTO pump and be happy with a fast, single direction splitter.

Defective · Mar 6, 2006

Ian,

Having split much more than my share of firewood over the years, I would strongly recommend against a bi-directional splitter. The only time these actually speed anything up is when you have 2 operators (one feeding each end) and that's just a bad way to hurt someone.

Add to this the simple fact that you should be able to mount an auxiliary pump to your PTO for less than it will cost to make a functional two-way.

Keep in mind that a wood splitter is a high stress machine so you want to keep it as simple as possible so that you can beef it up or repair it easily when something breaks.

MadDog · Mar 6, 2006

The two stage pumps are designed to produce rated flow at about 3500rpm, however it is not difficult to produce that from your pto by ramping the speed up by means of rpm increasing gearbox and pulley wheels.

The point of a two stage pump is that it runs most of the time at higher gpm (up to 750psi + or -) and then switches to about 1/4 the gpm to produce higher pressures when needed. With a 4-5" cylinder you shouldn't need higher pressures except when going through a knot or twist, so you get high speed most of the time and higher pressure (but lower ram speed) only when you need it. At 23.5 pto hp (a bit more than mine) you should have plenty of power to run a 2 stage pump at well less than rated engine speed to produce rated pto hp, provided that you use gearing/pulleys to get pump up to rated output rpm.

My memory is that the 22 gpm Barnes 2-stage runs about $300 and the 28 gpm about $370.

I wouldn't worry too much about running your diesel a bit higher than 1200 rpm; they're made to go all day at full rated pto rpm and if your pto rpm is about 2500-2600, running at 1900-2000 is just loafing. /forums/images/graemlins/grin.gif

IanM · Mar 6, 2006

Gentlemen--thanks for sharing your expertise. You make a lot of sense, and I'm now seriously considering going the pto route.

I have twenty plus doug fir saw logs, 16 and 20 footers, that I'm going to turn into fire wood. Those are the ones on the ground. There are others to fall. They run 3.5 feet in dia. on down. I can't budge a 16 inch slice of one or those and have to move them around with my fel. They are mostly clear but the few knots they have are massive. I've milled up all the lumber I can use and can't get anyone else interested. Apparently too much hassle for people. Would it be better to plan on a lifter for my splitter or one that will work vertically as well as horizontally? I'm renting a comercial horizontal/vertical one this week when the rain stops to see how I like it. I wonder about stability.

MadDog-

The two stage pumps are designed to produce rated flow at about 3500rpm, however it is not difficult to produce that from your pto by ramping the speed up by means of rpm increasing gearbox and pulley wheels. <font color="blue"> </font>

My L2550 has two pto speeds 540 and 1000. Is there any reason not to use the 1000 setting for this application and thereby reduce the amount of gearing necessary to get it up to the optimum speed? In the 12 years I've owned my tractor I've never used the 1000 pto speed. Mower, sprayer, post hole digger, all have specified 540.

Ian

OkieG · Mar 7, 2006

The YardMan splitter I use is a tow-behind that pivots from horizontal to vertical. An hydraulic lift would be very cool. A pivot system is almost certainly less expensive, though, it takes a little elbow grease to manuever a large log section under the vertical ram. In my experience, stability isn't an issue with a vertical ram. The YardMan has a spring loaded mechanism to lock the ram in either horizontal or vertical positions.

OkieG