RPM question

Discussion in 'General Electronics Chat' started by C44play, Nov 8, 2013.

  1. C44play

    Thread Starter New Member

    Oct 8, 2013
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    If you have a gear motor with an rpm of 100 and a ratio of 25:1 what does that mean?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It means the motor must run at 2500 rpm to attain the 100rpm out.
    Max.
     
  3. Stuntman

    Active Member

    Mar 28, 2011
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    Additionally, realize this reduction in RPM's means the same ratio of increase in effective torque, which is often desirable.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Minus losses, those cheap little 100:1 gearboxes might be as poor as 40-50% efficient. So it gives;
    torque *100 *0.50
    :)
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    How do you figure that? Why are you multiplying the torque by 100 when the gear ratio is 25:1?
     
  6. killivolt

    Active Member

    Jan 10, 2010
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    I think you mis-read his post?

    Edit: Maybe I'm the one mis-reading yours:confused:
     
    Last edited: Nov 9, 2013
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Temporary stupidity. :)

    It should have been *25 as I mixed up the 100 RPM and 25:1 gearbox.
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    I didn't even spot that you specified a 100:1 box in your post because I was expecting it to be 100rpm, so your post was consistent with the box you were talking about.

    We all tend to see what we expect to see, don't we? I guess it's a tendency that often serves us well in lots of situations. But when details count, it's a pain in the ass.
     
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