Hydraulic pump type and size.

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Guv

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For a proposed log splitter on the lines of a Rex 600 or similar I have a Deutz engine that produces 33hp at 1500rpm or 38hp at 1800 rpm and intend to use a ram Cylinder of 5” dia with 3.5” shaft with a stroke of 24” so the question is what type and size of pump will I need for fast cycle times with good splitting power, the only other hydraulic device would be a lifter.
 
I’ve used Bailey’s also, I liked them. Many years ago I had a Bliss splitter that ran off the tractor PTO, they recommended a minimum of 40 HP. I had a JD 2010 diesel that ran it well. I also used my neighbors Ford 641 which was a little bigger than the flat head N series. The Bliss had its own single stage pump, blade cut both ways. It was the base of many processers back in the 80’s. I went on a job at a flat rate of $40 @ cord, stacked between trees. A cord sold for $100 then. The home owner said all the wood had been cut to length and I didn’t need a saw, so I didn’t take one. Got there and found limbs 10” diameter 15’ long. I didn’t know what to do, so I tried cutting them to length with the splitter. It snipped them off like tooth picks. Running something like you want, build it tough, then double it. Lots of webbing and gussets. I like the type of machine you want to build.
 
Guv Welcome to the forum. Another good supplier of hyd components is Surplus center in Lincoln Ne. Look them up on line they have a hyd calculator in there tech section you can you can plug some numbers into and see what GPM single stage pump that size motor will run. That size motor will make a five inch cylinder run real nice.
 
I could only wish I had your problem!! With a engine like that.... wow.
a 5 inch cylinder (if you have 3/4" ports) fed with a 22 gpm pump makes a nice combination. Lots of tonnage and good speed of very close to 8 sec cycle time on a shorter stroke. Now.... to get that at 1800 rpm, means sizing the pump correctly. With a large diesel like that I would actually consider skipping the 2 stage pump. You have the torque to use, but be warned... blocks can explode when split that fast and hard.
 
A 5in bore cyl is still a little slow, even with a 28 gpm 2 stage pump. Your 3.5 in shaft will help some. Your diesel engine is only going to pull about 20gpm at 3000psi and 1800 rpms. The good news is it will pull 40gpm at 1500 psi. With 40gpm, you can get some serious speed out of your 5in bore cyl. How fast and how many tons you need your splitter to be is up to you. Just remember you can always throttle down the engine if the splitter is to fast, but you cant speed it up unless you have engine throttle to do so. A lot of good things can be said about using two stage pumps, but when building a high capacity machine, I think I would want the simple gear pump setup. Reason being is a simple gear pump will run forever as long as it runs clean oil. not a lot can go wrong with it like a 2 stage pump with its built-in unloader valve. This doesn't mean you cant have a two stage pump setup. You just need two separate pumps with a unloader valve mounted externally. You want speed, use 2 20gpm piggy back pumps and run one pump thru a separate unloader valve set at 1500psi, Set the main relief on the control valve at 3000psi. You machine will then flow 40gpm at 1500psi and once the pressure hits the 1500psi setting the pump connected to the unloader valve will dump back to tank and allow the second pump to produce 20gpm@3000psi. You have speed and power. About a 4.5sec cycle time. With the 5in bore cyl, I would guess a lot of your wood would split without ever unloading the first pump. you would have about 15tons of splitting force at 1500psi and almost 30 tons at 3000psi. You can also plumb in a dump valve for the return oil flow, but you will need a control valve that will handle at least 40gpm and a lot more gpm if a dump valve isn't used.
 
Hi Muddstopper, Thanks for the information, the engine is rated 40hp at 2000rpm, I can reduce the ram diameter but also have a 4ft section of driven rollers that needs to run full time so any advice would be appreciated
 
With 40hp, I think you will have more than enough power to do about anything you want. You are only limited to what you want and how much money you have to spend. You mention a 4 foot roller, I am guessing you are referring to a off feed conveyor to carry the splits away from the splitter. This type conveyor is usually low flow, and low pressure. Flow can be controlled with a restricted hose fitting or a simple flow control with its own relief valve. Finding a control valve might require a special custom job which means big bucks. You would need a three spool control valve, one for splitting, one for the log lift and one for the conveyor. You can buy single spool control valves and put them together as long as they are all power beyond which might save a few bucks, but might require a little creative plumbing to make it all work together. One thing to remember is just because you are using a second pump with unloader valve doesn't mean you don't have to account for residual hp requirement while the second pump is unloading. While this residual hp requirement is minimal, when you start adding other options such as a log lift and conveyor, you will increase the hp needed to run the entire operation. This will probably not be a problem since I suspect you wont be splitting while loading logs with the lift or conveying splits when you are not splitting.

Off the top of my head, without thinking it all the way thru or doing any calculation, I would suggest to power the log lift and conveyor off one pump and the splitter by itself off the other pump. You could use a two spool control valve rated for the flow of the one pump, which would be much cheaper than buying a 3spool valve that would flow the combined flow of both pumps. The 2 spool valve would have to be power beyond capable. The relief on that valve would have to be set higher than the unloader valve setting. From the power beyond, you would then plumb thru the unloader valve and then tee into the supply side of the second, single spool valve that powers the splitter cyl. The splitter valve would need to be sized for maximum oil flow of the combined two pumps. You will need a bunch of inline check valves and lots of hoses for return to tank. You can buy unloader valves that have the check valves already built in, which makes plumbing a lot cheaper and neater. You can also buy 2 spool control valves with built in flow controls and separate reliefs for each spool.

There is also the option to keep it simple, and cheaper, and use a 28gpm two stage pump, but pressure and flow fluctuations as the 2 stage pump kicks up and down while splitting might get on your nerves by the end of the day.
 
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