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What is a gear and what does it do?

  1. Jun 18, 2005 #1
    What is a gear and what does it do?
  2. jcsd
  3. Jun 18, 2005 #2
    A Quote from Wiki:

    A gear is a toothed wheel designed to transmit torque to another gear or toothed component. The teeth of a gear are shaped to minimize wear, vibration and noise, and to maximize the efficiency of power transmission.

  4. Jun 21, 2005 #3
    Thanks for the info.
  5. Jun 22, 2005 #4


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    To add to what NewScientist said, Gears are also many times used to increase torque (also lowering output RPM) or increase output RPM (also lowering output torque). Gears can also be used simply to reverse the direction of a rotation.
  6. Jun 23, 2005 #5


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    There are also many types of gear designs intended for different applications. They range from straight-cut types such as in a clock, up to exotic things like hypoids (car differentials) and double-herringbone (heavy industrial use). Each has advantages under certain circumstances.
  7. Jun 23, 2005 #6
    Sometimes Gears are used to do super cool things! CHECK IT OUT!


    (OK IM SORRY, THIS LOOKS TOO GOOD TO BE TRUE, I think its computer generated, Ive never seen a tire roll like that before, it seems roll up that inlcine tooooo easily.)

    Ok now for the good stuff, check this guys machines out, simply AMAZING!


    I cant pick a favorite, but they are incredible! Click on the first one, the paper birds, its full of great gears and cams.


    cyrus :-)
  8. Jun 23, 2005 #7


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    I heard that that clip is actually 100% real. Those tires made me think whoooooooooooa wait a second but i was thinken about it and there may be a curve or ramp type thing that the tires are on instead of a straight board like it seems to be. That would mean the slightest bump would make it fall down an incline and go forward. Or it could have been a spring or something that is holding it.

    The very very first wheel to fall in the entire clip is suspcious too! Why is it turning like that????

    First time i found out how gears work and how they can convert torque... i went nuts. I wanted to build like a million things.
  9. Jun 23, 2005 #8
    I have an accord, and I had to change a flat, and im telling you, those things dont roll up inclines like that. The weardest part is, if you notice the 2nd wheel on the incline, it hits the third and final wheel, rolls back, but then rolls up again! How in the heck did it do that without backspin!?
  10. Jun 24, 2005 #9
    Those wheels were weighted at the top to make them inherantly unstable. Only a slight nudge would be needed to destabilize the system(the wheels) causing the wheels to roll. Make the weights big enough and the wheels will exen roll up a hill. Kind of like balancing a stick on a finger. The stick/finger system is inherently unstable and if not controller will collapse in most situations but if controlled the stick can be held in an unstable position for a long period of time. The animation is real though.
  11. Jun 24, 2005 #10


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    I read a story on that clip "cog". It took 602 takes. Each time set back up from the beginning and tried again. It was all caught in one shot.
  12. Jun 24, 2005 #11


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    Yeah, there was no animation involved, it's 100% real! It's my favourite advert of all time, with Honda's recent "hate something, change something..." ad coming second.
  13. Jun 29, 2005 #12


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    I was actually working for Honda in Market Quality when that clip came out. We got to see if before anyone and its definately 100% real.
  14. Jun 30, 2005 #13
    One question about gears. Is it absolutely vital like in RPMs of 3-4E5 for the teeth to have the same dimensions and thus fit perfectly into each other or if one teeth is short and has small width and the other is long and has wider width, can the gear survive under extreme conditions?
  15. Jul 1, 2005 #14


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    We use gear boxes that routinely go over 50 krpm in our testing. Right now I have 3 tests either going or in the works that are in the ranges of 38 krpm and 56 krpm. The gear design is crucial for the power and speed range. To get a set to mesh is the biggest factor that will set the geometry of the two tooth profiles (obvioulsy). Because of that, there will not be a whole lot of variation between the two sets. The higher in speeds and power you go, the higher up the AGMA grade scale you'll go. That is where the tolerances on the profiles become much tighter and the backlash between them becomes much more controlled.

    Lubrication becomes very cruicial as well at those speeds. One can have too much lubrication, so it is not a matter of simply throwing as much as you can at the gears.
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