BUILDING A LOGSPLITTER

[benkapitanec]

IS IT POSSIBLE TO BUILD A 40+TON LOGSPLITTER USING AN 8HP MOTOR, 16GPM PUMP AND A 7 IN. HYDRAULIC CYLINDER? YOUR THOUGHTS ON THIS.

 

[rdbrumfield]

Sure it is possible, but I don't think 8hp is going to give you that kind of push unless it is a 2stage pump, and it will be fairly slow with that size of ram.

how many blades are you planning to put on it. This one works great with a 5 inch ram. As you can see it only takes two pieces off the bottom as you work the round. Because of the large difference in dia of the wood I cut I found this is the most effiecent way to get it done. this one will do about 2 cord an hour if you can keep the wood to it. It has a 7 sec cycle time, no matter what is in it. One stage pump 33 gpm, 24hp. If I were to split comercially, I would put an oil cooler on it, but for my home splitting it is fine. Just finished up splitting for a few years. Lot of blowdown last winter so it will be dry by the time it hits the stove.

 

[rdbrumfield]

3 way knife

 

[bobodu]

If you've ever watched "Megamovers'......they lift brick buildings with a 5 horse. But I don't think you would want to take all day to split one log.

 

[bassgrinder]

IS IT POSSIBLE TO BUILD A 40+TON LOGSPLITTER USING AN 8HP MOTOR, 16GPM PUMP AND A 7 IN. HYDRAULIC CYLINDER? YOUR THOUGHTS ON THIS.

Here is the math for this (multiply cylinder piston diameter times 3.14 to get the area the hydraulic pressure will push against in square inches, next since your hydraulic pressure is measured in pounds per square inch you would simply multiply the area by your pressure to calculate your total force the cylinder will apply) So a 7 cylinder will give about 32.9 tons with 3000 psi. A 16 GPM pump will move the cylinder at a fairly good speed but like said if the pump is not two stage one the 8HP will die under the max splitting load. Also note that when a cylinder the manufacturer will list a maximum column load (at 3000 psi a 7 cylinder column load is 65940 lbs or 32.9 tons), a safe system will have a system relief that will keep the hydraulic pressure below what will develop a column load in excess of the lowest rating in any working cylinders in the system. Now you can install a special relief in the pressure line feeding a particular cylinder that has max column load that would make you need a lower system pressure than desired for the rest of the system, and more or less be covered, but that is not best manufacturing practice. I would use a machine design with 2 separate systems for a case like that. Of course with simple splitter you would normally only have your one cylinder to worry about, but it is something to keep in mind if you want to add lifting arms or something. I mention all this because you would need to run your system at about 3700psi to get your 40 tons with a 7" cylinder, while not impossible it would mean you should really limit everything in the system to having the 6000 psi rating as opposed to the 3000 or even 4000 (not enough safety factor for me) and that can run into some serious $$$. One last comment is that everyone I have known to take shortcuts in a hydraulic system have always been unhappy with result especially when compared to a system done right and ended up going back and rebuilding it like they should have built it in the first place, that includes a guy 30 years ago, who looked me and had the same name as me, and who was just leaning what I know now. So I will advise to take your time, research all you can, and do it right, with the right parts.
W

 

[chevyzr2s10]

Here is the math for this (multiply cylinder piston diameter times 3.14 to get the area the hydraulic pressure will push against in square inches, next since your hydraulic pressure is measured in pounds per square inch you would simply multiply the area by your pressure to calculate your total force the cylinder will apply) So a 7 cylinder will give about 32.9 tons with 3000 psi. A 16 GPM pump will move the cylinder at a fairly good speed but like said if the pump is not two stage one the 8HP will die under the max splitting load. Also note that when a cylinder the manufacturer will list a maximum column load (at 3000 psi a 7 cylinder column load is 65940 lbs or 32.9 tons), a safe system will have a system relief that will keep the hydraulic pressure below what will develop a column load in excess of the lowest rating in any working cylinders in the system. Now you can install a special relief in the pressure line feeding a particular cylinder that has max column load that would make you need a lower system pressure than desired for the rest of the system, and more or less be covered, but that is not best manufacturing practice. I would use a machine design with 2 separate systems for a case like that. Of course with simple splitter you would normally only have your one cylinder to worry about, but it is something to keep in mind if you want to add lifting arms or something. I mention all this because you would need to run your system at about 3700psi to get your 40 tons with a 7" cylinder, while not impossible it would mean you should really limit everything in the system to having the 6000 psi rating as opposed to the 3000 or even 4000 (not enough safety factor for me) and that can run into some serious $$$. One last comment is that everyone I have known to take shortcuts in a hydraulic system have always been unhappy with result especially when compared to a system done right and ended up going back and rebuilding it like they should have built it in the first place, that includes a guy 30 years ago, who looked me and had the same name as me, and who was just leaning what I know now. So I will advise to take your time, research all you can, and do it right, with the right parts.
W

You may want to recheck your calculations. Area of a cylinder is radius squared times 3.14. You may have mixed up the calculations of area and circumference. A 7in dia cylinder at 3000psi would produce about 57.7 tons of force. You would only need about 2100 psi to achieve 40 tons with a 7in dia cylinder. You would only need about 2100 psi to achieve 40 tons with a 7in dia cylinder.

 

[bassgrinder]

You may want to recheck your calculations. Area of a cylinder is radius squared times 3.14. You may have mixed up the calculations of area and circumference. A 7in dia cylinder at 3000psi would produce about 57.7 tons of force. You would only need about 2100 psi to achieve 40 tons with a 7in dia cylinder. You would only need about 2100 psi to achieve 40 tons with a 7in dia cylinder.

Yes thanks Pi R squared is what I should have used to find area, you are right I mixed it up with circumference. I though it seemed a bit compared to the last calc I did for a 5" cylinder The rest of course still applies and yes at 57.7 Ton / 3000 PSI it puts breaking 40 ton with 7" easily obtainable.