Limit Switch for use with An Electric Actuator

Discussion in 'The Workshop' started by aidank, Dec 4, 2019 at 11:09 PM.

  1. aidank

    aidank Well-Known Member

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    As part of my off farm day job, I spent some time with an electrician today repairing a servo positioner.

    It got me to thinking of a project.

    Its easy from a mechanical perspective to rig up an electric actuator such as this https://www.ebay.co.uk/itm/12VDC-El...hash=item41e694d833:m:mQG4X6Jdkgw-8qlnDuxkzRg to operate the manual actuation handle on the fertilizer spreader.

    More research would be needed to shoose an actuator the travel speedis too slow on that model.

    The good news is my ebay link even has a controller with it to allow me connect limit switches. (A limit switch is a switch mouted on the mechanism such that when it is made it will cut off the supply to the electric motor in the actuator and it will stop extending.) I

    ts easy using the comtroller to connect a limit switch.

    Its easy install the limit switch such that it is made when the actuator would start pushing against the maximum opening set via the manual control stopper.

    Thus Im looking for a v precise limit switch, a limit switch with a range of +/-1mm isn't much use, otherwise fert spreader won't open the same amount every time.

    any ideas?
     
  2. Arthur

    Arthur Well-Known Member

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    I've an idea, the hydraulic ram and flow restrictors from a scrap Rauch or similar, not being funny but by the time you have all that lot set up will you be saving anything and fert and electric components ???
     
  3. aidank

    aidank Well-Known Member

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    how does the setup work on the Rauch, a flow restrictor implies slow down the flow while still maintaining the same pressure, which will bend everything in a short time.
     
  4. Arthur

    Arthur Well-Known Member

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    Without the flow restrictors the small ram moves too fast which will make shite of the on/off mechanism.
     
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  5. Paw

    Paw Well-Known Member

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    I'm only familiar with an old Vicon with hydraulic. It used a single acting ram which closed the mechanism and a spring to open so the adjuster didn't get wrecked.
     
  6. Bog Man

    Bog Man Well-Known Member

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    My one used a small gas accumulator to close the ram .
     
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  7. fiatagri10090dt

    fiatagri10090dt Well-Known Member

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    How are you going to the move actuator when limit switch has power cut off to actuator when stops it?
     
  8. Paw

    Paw Well-Known Member

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    I’m no sparky so don’t know how they work, they just do. They are fitted on automatic gates and filler doors. They stop power at the end of travel but allow power for the return direction
     
  9. towbar

    towbar Well-Known Member

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    The actuator is too slow for starting and stopping at ends. Instead it should be used to reduce the flow of fertilizer but still have a hydraulic open close. It’s possible the actuator could be used to set a limit for the hydraulic opening especially if the opening was by spring return
     
  10. towbar

    towbar Well-Known Member

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    For accuracy you can use a linear actuator with an integrated potentiometer which will give precise reading of where the arm is
     
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  11. towbar

    towbar Well-Known Member

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    They use diodes across the limit switch to allow current flow in one direction only when limit switch is open. Hardi Sprayer’s use this also
     
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  12. KTM Farmer

    KTM Farmer Well-Known Member

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    You can eliminate the need for accuracy if you have the actuated slide opening fully every time, have a manual slide fitted directly above it for adjusting the spread rate. That’s the way Amazon’s spreader is done, good idea in my view, no issue with damage over long term causing rates to vary etc.
     
  13. towbar

    towbar Well-Known Member

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    Hard to retrofit a second slide though.
     
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  14. scoffcruddle

    scoffcruddle Well-Known Member

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    I’m fairly sure this is what my bogballe spreader has,it opens and closes as you go along,brilliant system I love it.
     

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