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My electric splitter - custom hydraulic powerpack

Post in 'The Gear' started by paulm81, Feb 17, 2013.

  1. paulm81

    paulm81 New Member

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    Several years ago when I still lived on my parents farm, I built a beast of a 3PH woodsplitter. DSC05843.JPG
    It worked okay, but the cylinder had only a 15 inch stroke and it weighed a lot! On the farm, I had access to a loader tractor though, so it didn't bother me. I moved the splitter to our new place and rigged up an electric hydraulic pump to run it, but it was such a beast to move around without a tractor and with the short stroke limitations, I ended up selling it. I bought a used Wallenstein WX310 which is meant for a tractor as well, so I just put some legs under it for a comfortable working height. I stuck with electric power though and built this powerpack: DSC06108small.jpg
    A lot of the parts are repurposed (pump, valve, filter, motor starter, wheels) but everything else still added up. The used motor was sold to me as 10 hp, but it's been rewound and the nameplate removed so I'm skeptical because the weight and shaft size are more typical for 7.5 hp. It works well though and in the end, I guess that's what matters. I like the fact that it's a lot quieter than a gas powered unit and there are no fumes. I split right inside my storage shed, although the motor and pump still have quite a whine to them so I would like to put some longer hoses on the splitter and set the powerpack outside the door. I also had to run a 40 amp service to the shed to run this machine, but I wanted power out there anyways, so the cost for that wasn't too bad.
    I also wanted to be able to use it for other purposes if it's ever needed.
    Dune, bioman, ScotO and 3 others like this.

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  2. raybonz

    raybonz Minister of Fire

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    http://www.liteco.ca/Portals/_Rainbow/images/default/Tools/3phmtr_calc.htm

    I like electric splitters, no smoke, quiet and reliable.. If you have an amprobe check your amperage then check that against the link I posted.. It is important to have both short circuit and overload protection on this motor..

    Ray
  3. paulm81

    paulm81 New Member

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    The motor has a built-in thermal overload and there is also an overload in the magnetic starter I am using. If either of those fail to trip, there is always the 40 amp circuit breaker.

    I have found that 95% of the time the motor is barely working, but I haven't split anything too tough with it yet. The motor stalls out at about 1800 psi or so, which is a good way to trip a breaker fast!
    raybonz likes this.
  4. MasterMech

    MasterMech Guest

    No relief valve or is it just set high? I'm guessing it's a single stage pump as well. 1800psi isn't going to make that WX310 a beast. Only gives you about 11.3 tons of force from that 4" cylinder.
  5. bogydave

    bogydave Minister of Fire

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    Very nice.
    40 Amps must make the meter spin ;)
    Quiet would be nice

    Portable to my wood cutting area would take some
    big wire but have thought about it.
    If the engine ever dies, I may put an electric motor on it.:)
    raybonz likes this.
  6. paulm81

    paulm81 New Member

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    The relief valve is just set high, even at 1700 psi the motor is pulling more than 40 amps. The relief valve that I rely on is my ears connected to my brain which is connected to my hand on the lever;)
    The pump is just single stage, something that I "liberated" from my parent's farm. A properly sized two stage pump would be much better suited to the motor. So far 11 tons has split anything I've needed to, but I haven't run into any real tough stuff yet.
    40 amps sure would make the meter spin, but it's rarely working that hard judging by the pressure gauge. Electricity from the grid will likely always be cheaper than gas anyways. Especially since the powerpack doesn't need any time to warm up and is never left running if I stop to move a few pieces away or something.

    As an aside about fuel versus electricity costs, I used to work on diesel generators. Some of the fancier controllers would show instantaneous fuel consumption while we were running load tests. When I worked there, diesel was about $1 per liter and electricity was about $0.10 per kWhr. During our load tests, the fuel cost was about three times the value of electricity produced.
  7. MasterMech

    MasterMech Guest

    Why not set the relief valve approprately so that you're not overloading that motor?
  8. paulm81

    paulm81 New Member

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    Because it's hard to define what "overloading" is for an electric motor. If I simply went by full load current, I would only get maybe 1000 psi (just guessing). This motor can easily take short bursts of 150% load, such as what's needed to crack a tough block. If I get carried away, the overload or breaker will trip.
    My parents have a silo unloader with a similar motor, and it routinely pulls 150 to 200% full load current for short bursts, and even stalls once in a while. Occasionally, the start winding will give it enough torque to get going again after stalling, or the overload will trip. Wait five minutes, reset the overload, try again! It has been doing this for over 20 years.
  9. MasterMech

    MasterMech Guest

    I would set it for say 1700 or something, just so it doesn't stall the motor. Like you said, you are the safety in this case. But overloads and breakers are not supposed to trip "routinely". Sounds like you really need a 2 stage pump. They aren't all that expensive either.

    Any one of these will turn that setup into a beast! I'd say you have more than enough motor to run the 16 gpm unit and you'd probably never trip that thermal overload again.
    http://www.northerntool.com/shop/tools/category_hydraulics pumps 100-250 4294920625

    I've got a little experience with silo unloaders, they are wiley machines at times. ;)
    ScotO likes this.
  10. paulm81

    paulm81 New Member

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    I agree, routine tripping will weaken them over time. I also agree on the two stage pump.
    By my math, I could run something bigger because I only have 1750 rpm, whereas the pumps are all rated for 3600. For example, this one:
    http://www.surpluscenter.com/item.asp?item=9-7971&catname=hydraulic
    0.465 cu. in per rev. x 1750 / 231 = 3.5 GPM x 3000 psi = 6.13 hp according to this site:
    http://www.calcunation.com/calculat...=yes&Calculate=Calculate Hydraulic Horsepower
    On high flow, 1.86 cu. in per rev x 1750 / 231 = 14 GPM
    To stay under say 7.5 hp, I would need the changeover pressure at or below about 900 psi, which is the high end of the range anyways.

    I think the bolt pattern even matches my current pump . . . . hmmm . . . .

    How would a two stage pump handle other applications such as say a press or shear? Is it possible to lock them to low flow?
  11. MasterMech

    MasterMech Guest

    Would up the capacity of both, if they can take the pressure. You could set the unloader fairly low and it wouldn't take much to kick the pump into low flow mode but I don't think you could "lock" it there unless you could shim the unloader valve open somehow.
    ScotO likes this.
  12. raybonz

    raybonz Minister of Fire

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    Well that depends.. Look at the motor service factor (SF) if it is 1.0 you must protect the motor at 100% nameplate rating if you have a SF of 1.15 you can overload protect up to 115% or nameplate rating however I always go to 100%.. I also agree to set the pressure so as to not stall the motor..

    Ray
  13. nate379

    nate379 Guest

    If in needs 40 Amps, it's probably a 10hp or a bit more.

    7Hp would only draw about 25 amps.
  14. paulm81

    paulm81 New Member

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    I don't really know the specs of the motor since the nameplate is missing and it has been rewound. The motor has an overload, so it is protected, but being a thermal device, an overload can take short bursts of higher than rated load before tripping as long as it is running less than rated amps the rest of the time, or running in a cooler than rated temperature. This is no different for the motor.

    Electric motors can take a fair bit of short term abuse, just can't let them get too hot!
  15. SolarAndWood

    SolarAndWood Minister of Fire

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    I run my 5hp electric/16 gpm Haldex all day long without a problem. They seem to be fairly well matched and move a 4.5" cylinder as fast as I can feed it.
    bioman and raybonz like this.
  16. nate379

    nate379 Guest

    Anyone know how to compare gas vs electric in terms of cost?

    If that motor was run at full power, let's say 7hp it would be using about 5 kw/H, or at my electric rate, about $0.80 an/hour.

    SolarAndWood, I have a 16gpm going on my splitter, 2" cylinder. Hoping it moves at a decent speed.
  17. MasterMech

    MasterMech Guest

    It's going to take astronomical electric rates to make $4 a gallon gas attractive from a cost standpoint.

    2" cylinder? If that's right it'll cycle damn quick indeed. 16 gpm extends and retracts a 3.5" cylinder in 8 seconds, my 4.5" cylinder in 12. All that assuming a 2" rod diameter and a 24" stroke.

    Plug your specs into this Nate.
    http://www.calculatoredge.com/mech/speed hydraulic cylinder.htm
  18. paulm81

    paulm81 New Member

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    Is this motor 1750 rpm or 3450? The Haldex pumps are rated for up to 4000 rpm, so at 1750, the flow rate would be much less.
  19. SolarAndWood

    SolarAndWood Minister of Fire

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    3450...its a motor off a rotted air compressor. I wasn't sure how it would do running continuously for hours but haven't had a problem with it and the price was right.
  20. paulm81

    paulm81 New Member

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    That's promising to hear! Looking at the specs on that pump, it's rated 3.5 GPM at 2500 psi which works out 5.1 hp. For my 7.5 hp motor at 1750 rpm, I would have no trouble handling the 28 gpm pump I previously mentioned. Of course, I would only have 14 gpm or so due to the slower motor speed. Based on the speed calculator MasterMech posted, the cycle time for a 4x24 cylinder with 1.5" rod would be just over 10 seconds, obviously more if the high pressure stage is needed.
  21. SolarAndWood

    SolarAndWood Minister of Fire

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    That's about where I am. IMO, more than fast enough for a guy working alone especially when the vast majority of the rounds get short stroked anyway.
  22. Bret Chase

    Bret Chase Minister of Fire

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    16gpm with a 2" cyl? I wouldn't get my hand in front of it!
  23. Dune

    Dune Minister of Fire

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    !0 hp would be 42 amps at 220 volts.
  24. Bret Chase

    Bret Chase Minister of Fire

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    a 2" dia 24" long, 1" rod cylinder would extend in 1.2 secs... and retract in .9.... that would be phenomenally dangerous... and would only give a touch over 4.5 tons pressure with a 3k pump

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