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Vertical movement turning a gear

  1. Dec 17, 2013 #1
    i am still newbie , i dont even know if this question should go here or not , but i will ask it anyway.
    I have a rod that moves vertically , i need use this rod to make a shaft turn. So i had an idea, what if i made this rod toothed and make it move a gear as it goes up , will that work?
    if no , why?
  2. jcsd
  3. Dec 17, 2013 #2


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    A straight rod with gear teeth is called a rack. It could drive a gear wheel on a shaft but would need to be held in contact with the gear.
    Depending on the rotation angle required an alternative could be to use a crank.
    Also consider a tape or cord on a drum. Maybe with an idler.
    I would consider a stepped rubber belt running over a stepped pulley on the shaft, with an idler gear.
  4. Dec 17, 2013 #3
    I am still in high school , so if you can give a site or a book or something so I can know what's an idler , crank and all those things , that would be appreciated
  5. Dec 17, 2013 #4
    I checked what a crank means , I don't think I need it , I just need to make the shaft turn , later it will turn a wheel , another thing , if the rod moves up the gear will turn anti-clockwise if it moves downwards, the gear will turn clockwise , is there anything I could to make the shaft turn in one direction in both cases ( the shaft doesn't have to be connected to the main gear )
  6. Dec 17, 2013 #5


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    If you have two parallel racks joined and driven from one end, but with the racks on different sides of the gear, then the direction of rotation will be decided by which rack you engage with the gear. To travel continuously in one direction you must alternate between racks as they reciprocate.
  7. Dec 17, 2013 #6
    A ratchet. Movement in one direction, but only in a single stroke. Would be notchy, but could be butchered from an old bicycle.


    Sprag clutch. Movement in one direction, again only on one stroke, and you can keep a rack constantly engaged.
  8. Dec 18, 2013 #7
    @baluncore, your idea could work, but i can't use more than one rack
    @xxchrisxx, what i meant is not that i want the gear to move in only one way , i meant if you know a combination of gears or something that can make a shaft turn in same direction despite of the movement of the rack, like a motor piston ( i know it works differently than a rack ) i moves up and down , but the wheel turns in one direction
  9. Dec 18, 2013 #8
    I'm fairly sure you can do it with a series of clutches, but it'll be a total nightmare to set up so it doesn't jam.

    But if you really want a smooth input, with the linear input driving in both directions.


    You'll need a crank.

    This mechanism is basically a crank slider.
    The problem with a crank is, you need to start it spinning the way you want and keep the momentum up. If not it'll jam at the top or the bottom, or go the wrong way.

    Think a Railway Handcar.
  10. Dec 18, 2013 #9
    I am gonna connect a generator to the shaft, maybe if this gonna be complicated , maybe it wont matter , the generator produces AC anyway , right ?
  11. Dec 23, 2013 #10
    Last edited by a moderator: May 6, 2017
  12. Dec 23, 2013 #11
    thanks, if you know any other book about mechanical design please tell me it's name ( preferred to be a book for newbies and not advanced )
    Last edited by a moderator: May 6, 2017
  13. Feb 14, 2014 #12


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    this cute animated picture I enjoyed this thread so much that I want to add the first thing that came to my mind: Hey, these early steam engine fellows had the same problem !

    Also a little bit because I wondered how it could be that this thread went off to pretty complicated stuff (lots of wear, etc.)

    Re the AC generator: yes they produce AC (DC with a commutator or with a rectifier circuit). But they like some constant driving. A rack up and down might not be ideal, if the up and down is a sine.
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