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  1. #1
    150+ Forum Groupie flatlandpilot's Avatar
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    hydraulic actuator

    hello,

    I've a question,
    making an actuator from a hydraulic pump, cylinder and
    36V 20 A direct current motor.

    I added a NormallyClosed manual valve to get rid of the air in the system

    Has anybody tried this before ?


    Do you think this a good plan ?

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  3. #2
    500+ This must be a daytime job autocadplease's Avatar
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    Re: hydraulic actuator

    I believe it is just like "bleeding" brake lines. Add fluid until you get a constant flow out of the top of the system. I would think your diagram is fine.
    Grant D.
    Nelson,B.C. Canada
    Win7 32bit, FSX, PM Boeing, TH2GO, GEX, VoxATC

  4. #3
    150+ Forum Groupie verticallimit's Avatar
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    Re: hydraulic actuator

    My first concern is whether the pump is powerful enough.
    36x20 = 720 Watt
    Is there enough force, is it quick enough.
    Some pumps allow much pressure, while others are much flow.
    I can not see that you not have a valve to control the up and down direction, this is normal.

    If you must use it to motion platform, I think it will come to make an incredible number of starts and stops, the motor has a higher starting currents and could easily become too hot.

    Normally, the hydraulic pump runs continuously, and then it is the valves that determine the movements.

    I have my knowledge of hydraulic from the lift industry.
    I have not yet reached the point to build a motion platform.

    Hope it helped a little.
    Sincerely,

    Claus


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  6. #4
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    Re: hydraulic actuator

    Hi,
    Please don`t use hydraulics if you don`t have the knowledge about high flows or pressure.
    To be save and working, you have to calculate so many parameters and variables , it`s not for the amateurs.
    Did you work out how much actuators you need for your platform, do you know the total weight, the amount of Kn or kgF the actuator has to have at a certain rate off movement and these are the easiest questions.
    I`m working in the winch and capstanindustry, and we use hydraulics a lot.
    I have seen a 3ton winch being catapulted from a secured testrig , because a setting was not corrected.
    Even I will use an electric actuatorsystem despite I have the knowledge and means of calculating and purchasing hydraulic-parts.
    greetz

  7. #5
    150+ Forum Groupie flatlandpilot's Avatar
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    Re: hydraulic actuator

    how much actuators you need for your platform, do you know the total weight
    2DOF, 2 cilinders, 2 motors
    the cockpit wil be in balance and weight neutral over +-20 gr. X and Y
    and weights 200 kg.

    720W in (thats what the driver can take) motor eff 80% mech 90%
    so I hope to have approx 500W mech. power to move my pit
    (I already feel lucky liking the heavy metals )


    When once you have tasted flight,
    you will forever walk the earth with your eyes turned skyward

  8. #6
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    Re: hydraulic actuator

    And as you know as soon as your cockpit is moving the central gravity is moving also.
    You have to calculate weight x momentum arm x 0.5 ,
    thats the force you need to move your platform.
    Do you know the pulling and lifting force( kilonewton or kgF for the oldies) of the actuator and flow.
    The flow will be critical it regulates the speed and change of movement, you dont want to be in a roll or banking when the plane on your screen is already starts to go in the opposite direction and the acuator has to build the pressure for movement.
    the 500 watt is probably the powerconsumption of that motor but doesn`t tell you anything about the force/speed the actuator can/will produce.
    You have actuators that moves millimeter a second up to metres a second
    I don`t want to put you off on your project, but you have to know what your doing.
    A high presured hose can slice off an arm or worse if something burst because off wrong calculations and/or setting.
    Maybe I see too black but I can`t warn people enough when playing with forces.
    Remember force can put a 40 ton plane on a carrier in to the air in seconds
    greetz

  9. #7
    150+ Forum Groupie verticallimit's Avatar
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    Re: hydraulic actuator

    If I had to make the same project, I would use motors with gears and drives, 3 phase motor with electric fans for cooling.
    Hydraulics is a mess (leaking oil) and does smell.
    You can very easily get someone to configure the motors and gear, you need, so you only receive the necessary force.
    And the price I think in the long run is cheaper.
    Sincerely,

    Claus


  10. #8
    25+ Posting Member Skylane's Avatar
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    Re: hydraulic actuator

    Hi there,
    I'm new to this forum but want to give you some suggestions if you insist in hydraulics.

    Several years ago a motion cockpit was build using hydraulics (as far as I remember HCC Haagse Computer Club build it mid 90's). For the hydraulics they used a power stear unit from a Ford car, pump and actuator.
    On the other hand a very simple, reliable and cheap solution is the use of Citroen hydraulic parts from a BX or XM car. The valveblock is electrically driven and the high pressure pump is a pully type that could be driven by a normal AC electric motor using a standard V-belt.

    Hope to have given a contribution to your quest,
    Nico.

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