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Gearbox Problems

  1. Aug 29, 2006 #1
    Hallo all!!

    Anyone have any legitible info about gearbox? It's theory, it's ratio, it's calculation, everything about gearbox?
  2. jcsd
  3. Aug 29, 2006 #2


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    Welcome to PF, ecid. I'm afraid that your post doesn't quite conform to the way we do things here. What you are essentially asking is for someone to write a very big book for you (illustrated, no less). Gearboxes are in fact an extremely complex subject. What you need to do is ask specific questions, one or two at a time, and we can deal with them as they arise. It would help if you tell us how much you know already, and what level of education you're at. :smile:
  4. Aug 30, 2006 #3

    My mistake.... :bugeye:

    I need info about gear calculation in a gearbox, the ratio calculation, if i'm not mistaken, and just a simple n short theory of a gearbox, if it's possible.

    Now i'm in my last year of my electrotechnik diplom study, i'm doing my final now, and i know null about gearbox, and unfortunately i occupied my self with it. :redface:

    i've browsed it, but only found about gear, not it with the box.

    oh yeah, i'm working on a 12V stepper motor with a gearbox.

    so.. how is it?
  5. Aug 31, 2006 #4


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    I'm a bit confused about your problem. You say that you found 'gears', but not 'gearboxes'. That's all you need for calculation. A gearbox is just some gears... in a box. Your ratios work the same way: compare the number of teeth on each gear. The end result is the cumulative interaction. For instance, a gear with 100 teeth driving another with 50 gives a ratio of 2:1. If it's turning at 20 rpm, the driven gear will turn at 40... in the opposite direction. (The torque will essentially be cut in half as well.) Now say the second gear shares a shaft with another 100 tooth piece, which in turn drives another 50 tooth one. Since the ones on the same shaft are turning at the same speed, the final gear will be driven at 80 rpm, with approximately 1/4 of the original torque, and will be turning the same way as the first one. No matter how many gears there are in series, you just keep adding them up like that. The torque doesn't follow the exact ratio because of efficiency losses such as friction, but it's close.
    The only other things to worry about in a boxed set of gears are heat control, lubrication, and shifting mechanism (if any).
  6. Aug 31, 2006 #5
    okay... thanks a lot.. i think that's what i need....
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