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  1. #1
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    Default Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Let me preface this post by stating, that yes, I did search this site as well as arborist site and many others on this topic. I just have a few things that I want advice/clarification on before moving forward.

    Our hunting club has passed on the responsibility for me to have a custom splitter built for cabin use, and since I teach with a manufacturing teacher who has happened to build these with his upper level students for the past two years, it only made sense to go this route. The students benefit, the club benefits, and we (hopefully) get a unit that is built to our needs at a price much less than the higher end traditional commercial units.

    Our club wants a splitter than can split 38" logs, but have a 40" log capacity (we can certainly cut our wood to fit our fireplace at 36", but the majority cannot be convinced otherwise). As such, we were initially limited to a few specific heavy duty commercial units in the $8K range, or have one custom built by a manufacturer (also $$). Instead this is our plan.

    I'm specing out the cylinder, engine, hoses, valve, and pump. Everything else will be manufactured mostly in house by the instructor and his students (under supervision of course). It will be basic I-beam frame with a reservoir built into the top of the axle. Based on some calculations, I think a 5" bore/36" stroke/3000PSI cylinder will do the trick on all but the gnarliest 38" pieces (and even 40" pieces). I plan to run a Haldex 22GPM 2 stage pump (based on my calculations), but am unsure of what HP I need to drive the pump, since I can't plug in the numbers in the GPM x PSI x 1714 formula? I know two stage pumps have a high volume/low pressure and high pressure/low volume, but I can't find the specs as to what these are from the pump manufacturer. What GPM figure (once I find it) would I use to calculate the HP requirements? I'm assuming the low volume high pressure side?

    Secondly, what are the calculations for figuring hose diameter for both the supply and the load side? I'm looking at prince 4 way/3 position valve with 3/4" in/out and 1/2" working ports.

  2. #2
    Super Star Member J_J's Avatar
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Last edited by J_J; 10-15-2012 at 04:34 PM.
    J.J.

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  3. #3
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Thanks for the links. Confirms what I was thinking about the pumps. I found a 22GPM 2 stage pump on the link above, and it shows 6.3GPM on the high pressure side. Calculating HP for that gives me ~11HP. Should I assume 10% or 15% loss (90% or 85% efficiency) and factor that into the calculation? I was looking a Kohler Command Pro 14HP for this setup which would give me plenty, but I have also considered a Honda GX390 which is only a little over 11HP.

    As for the hoses, unless I'm reading that wrong, using 8fps for velocity and 22GPM for flow rate, I need a hose with an ID of 1.25"?? Or should I calculate hose diameter for the low flow side (i.e. 6.3GPM)?

  4. #4
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Ok, evidently I didn't read up enough on the subject of hose selection as I found a few good threads on here about the topic, and I re-evaluated that Nomogram you linked to. So here it goes.

    Using a 22GPM pump/5" Bore/14HP engine, it seems I would want about a 1 3/4" for the suction (using 4fps), 1 1/4" for return lines, and around 3/4" for pressure lines. Now, the valve I'm looking at (4 way/3 Position) has 3/4" In/Out and 1/2" working. I'm assuming that the in/out ports need an adapter for pretty much everything running these numbers? 1 3/4" from tank to pump, 3/4" from pump to valve, 3/4" from valve to cylinder, then would I run 1 1/4" from the cylinder back to the valve, and then 1 1/4" back to the tank?

  5. #5
    Veteran Member 6sunset6's Avatar
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    That's correct. How big is your tank? Rule of thumb says 1 gal for 1 gpm . I built one using that number and I think it is a little big. It depends on how long it runs and the outside temperature . You should have a return filter .
    Make sure the outlet of the filter is higher than the oil level in the tank. So when you change a filter you do not have a spill.
    How are you lifting those logs into the splitter. By hand gets old fast. As long as you are building from scratch ,one more valve and cylinder and you can have a lifter. If you use 2 separate valves make sure the first one in line has a power beyond port to feed the second valve. Or you could get a two spool valve but I like to separate the handles a little bit so the lifter does not get pulled by accident. I built one from scratch not quite as big but close. http://www.tractorbynet.com/forums/b...build-2-a.html
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  6. #6
    Super Star Member LD1's Avatar
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Sounds like you mostly got it figured out.

    On the filter, definatally do a filter. If you dont have it higher than the tank, or if it will be in the way, a simple ball valve will work for when you need to change the filter. No need for a high pressure valve either as the return side isnt high pressure. This is what we did on our huskee/speeco unit that has the filter down low and no valve.

    As to the tank size, generally on a 2-stage pump it is 2.5-3x's the high pressure flow. In your case, HP flow is ~6.3GPM, so you want a 15-20gallon tank. Obviously the bigger it is, the cooler the fluid will run, but the more expensive it will be to change.

    On the cylinder, I dont know if you already have one, or are buying used or new, but try to get one with the largest rod possible. Sometimes they are hard to find and when you do they are really expensive, but Ideally, one of those cylinders (like commonly found on some heavy equipment) that has a huge rod. Something like a 3.5 or 4" rod for a 5" cylinder. That will make the return cycle MUCH faster. If you cant find one of them, I think 5x36 cylinders commonly come in 2 or 2.5" rods. I would at least opt for the 2.5
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  7. #7
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Quote Originally Posted by 6sunset6 View Post
    That's correct. How big is your tank? Rule of thumb says 1 gal for 1 gpm . I built one using that number and I think it is a little big. It depends on how long it runs and the outside temperature . You should have a return filter .
    Make sure the outlet of the filter is higher than the oil level in the tank. So when you change a filter you do not have a spill.
    How are you lifting those logs into the splitter. By hand gets old fast. As long as you are building from scratch ,one more valve and cylinder and you can have a lifter. If you use 2 separate valves make sure the first one in line has a power beyond port to feed the second valve. Or you could get a two spool valve but I like to separate the handles a little bit so the lifter does not get pulled by accident. I built one from scratch not quite as big but close. http://www.tractorbynet.com/forums/b...build-2-a.html
    Thanks for the link and information! As for the tank size, I have to talk to the manufacturing instructor as to what size he typically builds (but those are for lower flow/smaller machines). We will definitely be incorporating an inline filter.

    I forgot to mention in the post (can't believe this) that there will be a second cylinder for a log lift, which is why I was looking at the 4way/3 position prince valve (RD523CCAA5A4B1). I see you recommend a second valve inline with this first. I never thought of that. Any other advantages to this setup other than safety vs. a single two handle valve?



    Sounds like you mostly got it figured out.

    On the filter, definatally do a filter. If you dont have it higher than the tank, or if it will be in the way, a simple ball valve will work for when you need to change the filter. No need for a high pressure valve either as the return side isnt high pressure. This is what we did on our huskee/speeco unit that has the filter down low and no valve.

    As to the tank size, generally on a 2-stage pump it is 2.5-3x's the high pressure flow. In your case, HP flow is ~6.3GPM, so you want a 15-20gallon tank. Obviously the bigger it is, the cooler the fluid will run, but the more expensive it will be to change.

    On the cylinder, I dont know if you already have one, or are buying used or new, but try to get one with the largest rod possible. Sometimes they are hard to find and when you do they are really expensive, but Ideally, one of those cylinders (like commonly found on some heavy equipment) that has a huge rod. Something like a 3.5 or 4" rod for a 5" cylinder. That will make the return cycle MUCH faster. If you cant find one of them, I think 5x36 cylinders commonly come in 2 or 2.5" rods. I would at least opt for the 2.5
    Thanks for the tip on tank capacity. As for the rod diameter, I never thought of that. I'll look into that as well.



    Does anyone have a recommendation for a secondary lift cylinder? How should I size that?

  8. #8
    Super Star Member LD1's Avatar
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    Quote Originally Posted by MGH PA View Post



    Does anyone have a recommendation for a secondary lift cylinder? How should I size that?
    That one is going to be a little tougher to answer. It is all going to depend on how it is designed. IE: you can use a long stroke and small bore cylinder or a short stroke large bore cylinder or anything inbetween.

    What you need to do is sketch out some rough dimensions as to how big the log lift is going to be (from pivot to ground), and where you plan on attaching the cylinder to it at. Then you can get a rough Idea of what you need length wise (retracted and extended measurment). This will get you the stroke length you need. And then just depending on where its mounted (leverage), and the angle it is mounted on, and we can figure out the force needed. (bore diameter).

    But it is going to me a MUCH smaller cylinder than the splitting ram. So unless you are wanting to build a firewood catapult, you may need to incorporate an adjustable flow valve in that circuit.
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  9. #9
    Super Star Member J_J's Avatar
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    I am thinking for the tank, it should be about 1.5 times the GPM of the pump. However a lot of commercial log splitter use smaller tanks .

    It seems that modern day hydraulics for mobile hyd is going to smaller tanks and perhaps adding a radiator and fan to help cool the fluid if needed.

    If you are wanting to build a beast, then go for the 5 or 6 in cyl, but I doubt you will ever use the potential that the large cyl will provide.

    If you look at the size cyl that most log splitter have, it is the 4 in cyl.

    At 3000 psi, a 2 in bore cyl 1 in rod, will develop about 8 ton.

    -----------------3 in-----------1.5----------------------------10 ton

    -----------------4 in-----------2.0----------------------------18 ton

    -----------------5 in-----------2.5----------------------------29 ton

    There is a lot of over kill with large cyl, as most splitting is done using the 4 in cyl.

    If you put a hyd gage in the system, you will see the pressure that is developed at each moment. It is usually high pressure briefly, then the pressure falls off as the log is split.


    Larger cyl cost more.

    Speed is mostly determine by the GPM of the pump.

    If you want to get fancy, there is the log splitter auto valve where you set both levers, and the log is split and the rod returns automatically, then the log lift, and the hyd wedge cyl for up/dn.

    Fancy wedges that can split 4 ,6, 8 pieces at one push.

    http://www.tractorbynet.com/forums/p...plitter-3.html

    Go to post #26 and you will see a nice configured log splitter.

    The splitter wedge is stationary, and the wings move .

    http://youtu.be/1edm2kNMYZs

    http://youtu.be/SbYp0bVn4pI
    Last edited by J_J; 10-16-2012 at 02:34 PM.
    J.J.

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    Git er done.

  10. #10
    Super Member crazyal's Avatar
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    Default Re: Log Splitter Question(s)...Two Stage Pump and Situation Specific Questions

    There's a logger thinning a lot not too far from here. I pass it when I walk the dogs. I have talked with him in the pass but just recently I walked into his landing to see his splitter sitting there. Instead of a platform that you roll the log onto and then raise up his had a set of logging tongs on what looks like a engine lift. It swings 360 degrees. I don't know how well it works but looks like it would be very handy as you can just pull logs from a pile. I think it's a commercial unit but I've never seen one like it. Maybe others here have.
    Kubota L4240,Case 580K backhoe, Case 450 Dozer

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