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hydraulic speed control
  • Vote Up0Vote Down
    dorkmodorkmo
     
    February 2012
    heyo, im trying to help thad over at brokensidewalkfarm design a hydraulic system for a lifetrac that can be computer controlled. he's dubbed it "dronetrac."

    anyway so far its going to be based on a system similar to the ceb press. double acting solenoid valves controlled by arduino or another controller.

    since controlling speed isnt important on the ceb press we're having to figure out how to speed up or slow down parts. this can be done by speeding up the power cube but it doesnt have much fine control at idle. also this limits doing two things at the same time at different speeds.

    there are some off the shelf choices like this: https://www.surpluscenter.com/item.asp?item=9-5178&catname=hydraulic

    i proposed using a needle valve with a stepper motor attached. using a basic valve: https://www.surpluscenter.com/item.asp?item=9-7961-8&catname=hydraulic
    kinda based on the needle valve controlling the secondary cylinder. http://www.youtube.com/watch?v=R6JE1l-IO5c
    perhaps interfaced with some sort of 3d printed contraption.

    does that sound like an okay idea? i was sorta dreaming at first about getting rid of the solenoids but then realized it'd be bad to get rid of the full stop ability.

    im not sure how to sense the fully open fully closed positions. can that be detected from the stepper motor driver when it meets resistance? or does there need to be an adjustable switch or something at either end?

    those are just some thoughts and questions im throwing out there. feel free to critique.
     
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  • Vote Up0Vote Down
    dorkmodorkmo
     
    February 2012
    also considered interfacing with one of these: 
    https://www.surpluscenter.com/item.asp?item=9-064-50-A&catname=hydraulic

    dont know much about the mechanics of it but thought it might hold up a little longer than needle valve?
     
  • Vote Up0Vote Down
    dorkmodorkmo
     
    February 2012

    was having that needle valve to control the speed of the secondary cylinder on the press successful? did you have to change to a different type of valve or did that work out?

    We ended up using a flow control valve - which has flow control plus pressure relief. Pressure relief is important so you don't bust a nut. 

    thad is wanting to control hydraulics with a controller, i suggested maybe a stepper motor turning a valve. does that sound achievable?

    That's the concept, to get it to work will be a challenge. Such systems are very expensive, so are worth developing.
     
  • Vote Up0Vote Down
    Matt_Maier
     
    February 2012
    Cool. I've been figuring that as the GVCS vehicles become more modular we'd end up moving to a drive-by-wire system anyway. You can have a cab that moves from vehicle to vehicle, and you can get out of the vehicle while still controlling it wirelessly, and control changes are easier, etc. 
     
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