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  1. #1
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    Default Hydraulic motors w/ undersized pump?

    What happens if I have a hydraulic pump that can not source the maximum GPM needed for a hydraulic motor (wheel motor). EX: 12GPM pump w/ a 20GPM motor?
    A) Will work just fine but will not achieve maximum speed.
    B) Will work just fine but will not achieve maximum torque.
    C) Will not work, like a pneumatic impact wrench it needs a certain minimum pressure and flow rate to operate.
    D) None of the above_______________.

    Thank you,

    Boris.

  2. #2
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    Default Re: Hydraulic motors w/ undersized pump?

    The answer is A. It will work just fine but will not achieve maximum speed.

    Aaron Z
    A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
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  3. #3
    Elite Member dfkrug's Avatar
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    Default Re: Hydraulic motors w/ undersized pump?

    You left out the max pressure developed by the pump, and the max pressure that
    the motor can handle. Simply put, the pressure put out by the pump will determine
    the max torque that the motor will put out. Not volume.

    Generally, you want to stay away from your motor's max volume spec due to the
    inefficiency at that operating point. You should look at the motor characteristics
    shown in your manufacturer's catalog. Charlynn, White, etc all publish nice PDF
    catalogs.

    So, running a 20GPM (max) motor at 12GPM should work fine at lower than max
    motor output speed as long as you don't exceed the pressure rating.
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  4. #4
    J_J
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    Super Star Member J_J's Avatar
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    Default Re: Hydraulic motors w/ undersized pump?

    The hyd pump is designed to pump a certain amount of fluid using maximum speed of the pump.

    It also has a certain pressure limit built in that is called max pressure.

    The hyd motor develops the pressure, and will use the available flow to do work. The hyd motor also has limits for pressure before the seals blow.

    If the hyd motor develops more pressure than the pump was designed for, something will burst, be it the pump, hose, valve.
    J.J.

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  5. #5
    Silver Member glastron23's Avatar
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    Default Re: Hydraulic motors w/ undersized pump?

    yes JJ the pump creates the flow , the pressure comes from the resistance to the flow of oil, be it a motor driving a wheel or a cylinder that is moving a load. The thing that you forgot is that the system MUST have a pressure relief valve to protect the hydraulic system.. the motor will not blow the system apart if it is designed properly...

  6. #6
    J_J
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    Default Re: Hydraulic motors w/ undersized pump?

    No, I did not forget about the relief valve as in most hyd system there is one or two relief valves per systems as standard design feature.

    I believe that about 95 % of all lever type hyd valves have a relief valve.
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

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