Hydraulic Log Splitter-concept question

[muddstopper]

I didnt get to see the video, but I am pretty certain he's not dumping the oil back into the rod end of the cyl. That would be like trying regen in reverse. It wont work because of the surface area of the piston. The bore side having the larger surface area would extend the cyl if you have equal pressure on both the rod side and the non rod side. Most likely is the dump valve is dumping oil back to tank and bypassing returning thru the valve. I dont see whats so hard about building a splitter with a 5sec cycle time. Use a bigger rod and more flow and you have it.

 

[triptester]

A hydraulic splitter with a 5 second cycle time for $1200. Nearly impossible. The least complicated method would be 4"bore x24" stroke with 2" rod cylinder ,14 hp engine, 28 gpm 2-stage pump. These 3 parts alone would eat up most of that $1200.

 

[logeeland]

Here is the link I just got about this machine.

Take a look

The video does not work

 

[logeeland]

I would buy one! I would have to see it in action also. If it was in the stores for $1200, it would have to be made for $500 for the manufacturer to make a profit. Then comes the shipping cost to the dealer, then the dealer markup. 25-50% each time. I doubt it could be made for $500. That is a $2000 machine.

 

[muddstopper]

A hydraulic splitter with a 5 second cycle time for $1200. Nearly impossible. The least complicated method would be 4"bore x24" stroke with 2" rod cylinder ,14 hp engine, 28 gpm 2-stage pump. These 3 parts alone would eat up most of that $1200.

I will agree that as a individual buying one cyl, one pump and one engine, it could get pricey. Heck, its almost impossible to build your own and beat the price of a factory machine. Manufacturers are not building one off splitters and they dont buy parts one at a time. The different in cost to manufactor a 4x24x2 in cyl is only marginable than building a 4x24x3 in cyl, if you are building hundreds of those cyl for a production line. To build a one off cyl it could easily double the cost between the two. I could build a splitter with a 2 sec cycle time, but I dont think its practical and wouldnt want to pay the price. The control valve alone for a splitter with that kind of speed would probably eat up most of the $1200 allotted for the project.

 

[Mike Van]

like to see the video

 

[muddstopper]

To get to the 22-27 tons he's seeking he would need a 4.5 bore cyl which would give him 23.5tons @ 3000psi. To get the speed down to 5sec, he would need a 28gpm pump and a 3.5in rod and 24in stroke. This would give him a cycle time of 4.9 sec. 28gpm @3000psi will need a 54hp engine to pull the pump. To keep the engine size down to something reasonable, he would have to use a 2 stage 28gpm pump and a 16hp engine. The amount of time the pump stayed in the high pressure/low flow mode would increase the cycle time above his 5 sec goal. His 4.5x24x3.5 cyl would have to have a minimum of a 1in return port and be plumbed into a dump valve back to tank and completely bypass the control valve. I havent done the math on oil return flow, but suspect somewhere in the neighborhood of 70gpm. Because of the increased velocity of the oil on return, he would need a hyd tank with a capacity of at minimum of 50gal, other wise oil foaming and then pump cavitation would start becoming an issue.

Even as a manfacturer buying material in bulk, the $1200 price tag would be hard target to hit.

 

[JeffHK454]

To get to the 22-27 tons he's seeking he would need a 4.5 bore cyl which would give him 23.5tons @ 3000psi. To get the speed down to 5sec, he would need a 28gpm pump and a 3.5in rod and 24in stroke. This would give him a cycle time of 4.9 sec. 28gpm @3000psi will need a 54hp engine to pull the pump. To keep the engine size down to something reasonable, he would have to use a 2 stage 28gpm pump and a 16hp engine. The amount of time the pump stayed in the high pressure/low flow mode would increase the cycle time above his 5 sec goal. His 4.5x24x3.5 cyl would have to have a minimum of a 1in return port and be plumbed into a dump valve back to tank and completely bypass the control valve. I havent done the math on oil return flow, but suspect somewhere in the neighborhood of 70gpm. Because of the increased velocity of the oil on return, he would need a hyd tank with a capacity of at minimum of 50gal, other wise oil foaming and then pump cavitation would start becoming an issue.

Even as a manfacturer buying material in bulk, the $1200 price tag would be hard target to hit.

You're over thinking this...it just takes a special cylinder.

 

[muddstopper]

You're over thinking this...it just takes a special cylinder.

Well, a 4.5 bore cyl with a 3.5 in rod would be a special cylinder.

There are a few things one can do to decrease cycle time, the easiest being throw more oil at it. You can also use regen to increase the extend speed, but it would decrease splitting force. Even that can be worked around, but not really efficient or practical, and is costly. for those that dont know, regen is a method to reuse the oil from the rod end port to help increase the extend speed of the cyl. It works by allowing the pressure to equalize in both ends of the cyl which will result in the cyl extending at a faster rate. It will not work as a method to retract a cylinders as the base side of the piston will have more surface area than the rod side of the piston. Regen will only extend the cyl, not retract. Since you would have the oil from the pump going to extend, as well as the oil from the rod end returning to the base, you can expect 2-3 times the actual oil flow going to the base of the cyl and a increase of 2-3 times in extend speed. The down side is you also reduce the available force to split your wood. Since you would have the rod side of the piston working against the base end of the piston, so you reduce force by whater ever the difference s are in the two surface areas. You will see this a lot on tractors loaders. The plumbing for this method is usually made into the control valve. Nothing saying you cant use check valves and unloader valves to rig up your own regeneration system. I would think to get the full benefit of using regen and still have the force necessary to split wood, you would have to use a unloader valve to direct oil flow to the base end of the cyl and then at a preset pressure, the oil would have to dump to tank. Pressure would have to be metered at the base end of the cyl and have a check valve to prevent pump oil from dumping into the return. This would allow the regen mode to be use for fast extention and full pressure to build full force. It would take some thinking on the plumbing because you would still need pump pressure to retract the cyl. Most likely need another unloader valve and check to make this happen. I would have to think about it a bit to come up with something that would work. Also, all that extra plumbing is just going to drive up the price of the splitter.

 

[Mike B.]

here is the video. sorry for the delay

 

[Mike B.]

I would buy one! I would have to see it in action also. If it was in the stores for $1200, it would have to be made for $500 for the manufacturer to make a profit. Then comes the shipping cost to the dealer, then the dealer markup. 25-50% each time. I doubt it could be made for $500. That is a $2000 machine.

would like to mark the machine more expensive than 1200. Not sure if the general public will accept that though.

 

[GM_Grimmy]

I'd like to know the specs of the cylinder and the pump. It looks like a 4" cylinder, 2" rod, and maybe a high gpm pump, appears to be 2 stages, as once it was in the wood, it slowed to a crawl. The wood looked like it was soft wood as well. There were many pieces that he forced apart by hand, defeating the purpose of the splitter, effectively making it look faster than what it really is. It appeared to have a studder in the stroke as well, maybe from changing stages or something. I'd like to know more about what makes the cylinder special. Appears to be simple hydraulics to me.

 

[logeeland]

would like to mark the machine more expensive than 1200. Not sure if the general public will accept that though.

People pay $6000 for a timber wolf.

 

[Mike Van]

To answer your original question, i'm going to have to see more than a one minute video splitting some short crappy tulip - Show the whole machine - What it's made of - Ram speed is nothing if it won't split a maple crotch without destroying itself.

 

[logeeland]

Mike hit the nail on the head. How does it split?

 

[Mike B.]

I'd like to know the specs of the cylinder and the pump. It looks like a 4" cylinder, 2" rod, and maybe a high gpm pump, appears to be 2 stages, as once it was in the wood, it slowed to a crawl. The wood looked like it was soft wood as well. There were many pieces that he forced apart by hand, defeating the purpose of the splitter, effectively making it look faster than what it really is. It appeared to have a studder in the stroke as well, maybe from changing stages or something. I'd like to know more about what makes the cylinder special. Appears to be simple hydraulics to me.

it's a 4" cylinder and 11GPM pump. All the machines state the cycle time is on empty run. when it hits some pressure, it will slow down. Sorry, I can't say more special details about the cylinder. They want to protect the technology until it's ready to launch.

 

[Mike B.]

To answer your original question, i'm going to have to see more than a one minute video splitting some short crappy tulip - Show the whole machine - What it's made of - Ram speed is nothing if it won't split a maple crotch without destroying itself.

I will. I just want to show some quick video first. More details will come soon. Thanks