Hydraulic cylinder use - Page 2
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  1. #21
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    Joe I run a hyd shop and did a job for a guy with a similar project. We took a big bucket truck cyl and modified it to fit a big splitter. The cyl used was 7” bore with a 4” rod.
    We shortened the barrel, plugged off the counterbalance valves and added 1” ORB ports. IIRC he had a big 2-stage pump but had to upgrade to about a 20-25hp engine to keep the engine from stalling. You may run into same circumstance.

    Your 1/2 ports and hoses will definitely be too small for the flow you need, and when considering a new valve you need to size it for the max amount of flow going thru the valve core, the flow will be greater on the return stroke due to displacement ratios in the internals in the cylinder.

    With a 8” bore your are pushing 50.26 sq in of area of displacement, comparing that to a typical 4” bore log splitter it is only 12.56” sq in. So that’s 4 times of everything to be sized up to run like a typical splitter (engine, hoses, valve, reservoir, filters etc)

    I've not needed a log splitter but I’ve always wanted to make one with two 4” hyd cylinders (one mounted above and parallel about 12” above). That way a regular 5 hp engine/pump could be used and a few high pressure ball valves and removable pins for higher cyl would allow the splitter to run normally for 90% of splitting but throw in a pin and unlock two ball valves and now the splitter is twice as powerful and half the speed for bastard wood, plus the higher cyl would give the stability with larger taller wood.

    Heres a pic of that cyl job last winter

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  3. #22
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    75f7720d-1e14-479e-8eb9-4fc0b3183469.jpg

    ......

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  5. #23
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    Too bad a little more design homework didn't go into this project. That huge cylinder with small plumbing could never achieve a respectable extend/retract time without a 400 horsepower pump at a bazillion PSI. Free isn't always the best choice.

    Stuart

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    15 gallons per minute will extend the cylinder in 30 seconds give or take. 30 gpm, 15 seconds. Most log splitter pumps are 2 stage, really 2 pumps in one. One larger and one smaller. Both pump up to say 500 psi, then only the smaller. Keeps unloaded speeds up, and horsepower demands down.

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  9. #25
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    Quote Originally Posted by PocoLoco View Post
    15 gallons per minute will extend the cylinder in 30 seconds give or take. 30 gpm, 15 seconds. Most log splitter pumps are 2 stage, really 2 pumps in one. One larger and one smaller. Both pump up to say 500 psi, then only the smaller. Keeps unloaded speeds up, and horsepower demands down.
    The ballpark figure for a 30 GPM pump at a standard 1500 PSI is 29 HP required. For 15 GPM it's still a whopping 15 HP required. Those are monster motors for simply splitting some firewood, in my opinion. Those extend/retract times are horrible as well.

    On a side note, I didn't realize Kansas had any trees.

    Stuart

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  11. #26
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    Quote Originally Posted by e-fishin-c View Post
    Joe I run a hyd shop and did a job for a guy with a similar project.
    Man, I sure don't want to take this cylinder apart, but I'd have to! I'm afraid of what I'll get into trying to remove the cylinder head... then putting it all back together after the work. Surely I'll mess up a seal, somewhere trying to put the piston back in.

    If I actually drained it and took it all apart, I bet the best method would be to use one of those magnetic base drill with an annular cutter. I'd do like you said and plug off the original manifold and just weld some new ports on...

    I think a friend of mine has a Milwaukee mag-base drill. If I could get ahold of a big annular cutter to use in it...if it has the right chuck to accept them....

    And, I do have two brand new 4" diameter x 40" stroke cylinders I got at an auction. I could always change this up and put those two cylinders on the splitter instead.

  12. #27
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    If you use the mag drill on a round cylinder you can take a piece of 1” flat bar and ratchet strap it to the cylinder so you have a flat surface to work off of. You may need to tack weld some rod onto the bottom of the flat bar parallel to the axis of the cylinder so the mag drill doesn’t torque the whole mess sideways.

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  14. #28
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    Quote Originally Posted by Flail View Post
    If you use the mag drill on a round cylinder you can take a piece of 1” flat bar and ratchet strap it to the cylinder so you have a flat surface to work off of. You may need to tack weld some rod onto the bottom of the flat bar parallel to the axis of the cylinder so the mag drill doesn’t torque the whole mess sideways.
    Better to use a short piece of channel iron. For 8-9" tube OD probably 6 7 or 8" channel, 1 foot long is good. If you do it more than once weld a hook for small chain to one side and a long threaded bolt on the other end of the chain, to stay attached through a heavy washer.
    Channel has a hook on one side and a "washer" on the other. Chain has a long threaded rod on one end for the washer, this tightens, the other end goes in the hook, adjustable for different sizes tubes.

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    yep, To weld up the port on the rod side you’d have to remove the piston/gland assy or you’ll fry the seals.

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    You can speed up the cyl movement to its load position by plumbing the rod end to the piston end through a pressure actuated valve that returns to tank when the set pressure is reached.Look at a bailer schematic they are all plumbed that way.It adds the volume that would normally go to tank to the advancing end to speed it up without requiring a pump speed increase.
    Look on line for American Bailer or Maren,maybe the schematics are available.

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  20. #31
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    Quote Originally Posted by ratbldr427 View Post
    You can speed up the cyl movement to its load position by plumbing the rod end to the piston end through a pressure actuated valve that returns to tank when the set pressure is reached.Look at a bailer schematic they are all plumbed that way.It adds the volume that would normally go to tank to the advancing end to speed it up without requiring a pump speed increase.
    Look on line for American Bailer or Maren,maybe the schematics are available.

    Called a differential valve. The ones I worked with were proprietary so I don't know what's available but I would bet it is and cheaper than 2 stage pumps and all the other fantasies.

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  22. #32
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    I understand what you're talking about. I looked on Baler's site.. those things would be called a "regenerative" valve. I found some on Ebay... for sale in GB, U.K. for $209... 3/4" ports. Not a large variety for sale.


    E-fishin-c: In your opinion, what is the minimum diameter hydraulic line diameter I should aim for to get acceptable piston travel? Acceptable.

    If I went with 1" ports on the cylinder, the 3/4" "work" ports in these control valves I've found would still throttle it down.

  23. #33
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    3/4” would be a good compromise, going with a manual valve with 1” could get pricey when you consider upgrading your other components. Max flow you’d want to see is 30 FPS, 15-20 FPS would ideal with whatever flow you have.

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  25. #34
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    Originally, I wanted to make this new splitter a stand alone unit... self contained. I may have to rethink my stance on that.

    My old unit has plenty of horsepower, with a comparatively low GPM pump. I built it in 1981 and the pump was bought out of the Grainger catalog and I have no idea of the specifics on it anymore. Most of the time, the engine idles when the splitter is in operation.

    Maybe I should just buy a larger GPM pump and mount it on the old machine, plumb in a pair of selector valves so I could power either splitter by opening or closing two valves?

    If I have a pump capable of operating an 8" cylinder at an acceptable rate of travel, would the existing splitters control system be too much of a restriction to the higher flow rate and cause overheating or something like that?

    Maybe I'm overthinking this...

  26. #35
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    Yes overheating and bogging down the motor. In hydraulics if you go from high pressure to low pressure without doing any work you are creating pressure drop (restriction) and heat.

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    here is a pump that will do close to what you need 28 GPM Dynamic 2-Stage Pump | 2 Stage (Log Splitter) Pumps | Hydraulic Pumps | Hydraulics | www.surpluscenter.com , you will just need to up your low-pressure side relief valve to the 900 side I would try it with the 1/2" lines you already have probably create a lot of heat but how long at a time are you actually going to run it for? anything that 30" long that needs 60 tons of push isn't going to quickly be rotated and pushed through again

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  30. #37
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    That would be a good sized pump, but min 16hp

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    You can easily find a pump to move it fast enough but then you need horsepower to drive the pump. That big cylinder will go through anything even if you were using a bicycle tire pump but it will take forever to get there. You've got a serious restriction there to deal with first and that is that manifold tube to the retract side of the cylinder. It looks to me like it is Ø1/2 o.d. tubing at most. That means you are going to get that oil hotter than the hubs of hell if you try to squeeze all that oil through it at the speed you want to. So you can get the cylinder moving slow and safely or fast and maybe blowing that line. I think I would go with your 4" cylinder and try to peddle that big cylinder off to someone who can use it. Bigger ain't always better.

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    The 4" cylinder at maybe 10,000 psi may have enough force. His cylinder is fine, he has a valve rated at 30 gpm, buy that surplus center pump, and a used engine, and get it working.

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    Or use the engine you have, and make some way to throw in or out the pumps as needed. If the oil runs hot, put a cooler in the return line to the tank.

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