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Need Info on Single Axle Dump, and Hydraulics!

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  • Need Info on Single Axle Dump, and Hydraulics!

    Hello, i was looking through the search function for some info on hydrualics and dump trailers etc but still need some help. What would be the difference between these two Power Packs.

    The first is from Princess Auto in Vancouver, it is
    Flow rating @ 0 PSI - A Single acting
    Flow rating @ 2,500 PSI - 2.8 GPM
    Relief setting (PSI) 1.3 GPM 2,500
    Relief range (PSI) 500-3,000
    Reservoir size (gal.) 0.75
    Ports #6 ORB
    PRICE 449.99 Canadian, (on sale for $400)

    THe Second is from Dalton Hydraulics from ? (somewhere in the US)
    Operation: Single-Acting
    Power: 12 VDC
    Capacity: 2.0 Gal
    Pressure: 3000 PSI
    Flow: 2.0 GPM @ 1000 PSI
    Ports: #6 JIC Male Connection
    * Power Up / Gravity Down
    * 2.0 GPM @ 1000 PSI
    * Single solenoid operated holding valve
    * 3000 PSI factory preset relief
    * Made in USA (this one is $365 US)

    So the questions would be, is the 2nd way better? Whats the difference between the two and are these prices good or where i can find something better/cheaper etc?

    I need something that will be able to pick up about 2000-3000 pounds and if any info on who sells hydrualic cylinders (maybe a 4" 40/30) cheap would be appreciated too. Thanks.
    Last edited by droptopgt; 09-12-2008, 12:26 PM. Reason: correction

  • #2
    The first one operates faster than the second. However, this means it draws more power.

    The first one has a very small reservoir. you wont be using it on a very big cylinder. In fact, it will exhaust its reservoir after 16 seconds of pumping. You can fix this by building a separate oil tank.

    How many tons of effort you need depends entirely on where you place the hydraulic cylinder. If you attach the business end near the middle of the bed at a 15 degree angle, it will require over 11,000 lb to lift an evenly distributed 3,000lb load. This translates into a minimum cylinder ID of 2.65". [Note: this is where the mistake was-radius somehow got divided by 2 instead of multiplied by 2, giving .66" min ID] Assume you'll need a 3" cylinder. Actual operating pressure at 11,000lb force... pressure =force/area=11,000lb/(pi*1.5^2)=1,560PSI.

    Figure the minimum capacity of your pump system to be at least the stroke volume of your cylinder ([3.14*[ID/2]^2*stroke length]/231cu in per gallon)

    Assume you have a 3"ID cylinder with 48" stroke
    r=1.5 pi*r^2*l =3.142*2.25*48=339cu in/231= 1.47 gallons

    You're already beyond the reservoir capacity of the first pump.

    Time to dump= 1.46gal/2GPM=.73min*60sec/min=44 seconds with the second pump - with a half gallon of oil left in the tank. This is assuming it runs 2gpm at 1500psi, althogh it is rated at 1000psi. In reality, it will probably bog down a little bit and take a full minute to dump this load.

    Just be aware that the eye brackets you fabricate may see up to 22,000lb depending on where the load is. Make sure the frame can tolerate this!

    Getting hydraulics to work right requires either engineering ahead of time, or trial and error (which usually consumes a lot of time and money). Note how badly a single incorrect keystroke (multiply vs. divide) messed up the original answer. It's better to catch mistakes on paper than cut them off and weld on the correction.
    Last edited by Bodybagger; 09-13-2008, 02:57 PM. Reason: a single incorrect keystroke of a calculator.

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