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A question about gear

  1. Sep 4, 2005 #1
    Hi all!
    I have a problem about the gears used in a winder as hown in the picture.
    You can see right in the front view of the picture, there is a counter, which is a pair of worm gear. The engineering drawing of this pair of draw is as shown in another picture.

    My question is, in the prespective of the mechanism of the winder, it seems that the winder will still work if only one worm gear with great thickness instead of a pair of worm gears is used. So what is the reasons for using a pair of worm gears instead of one only?

    Second, the pair of worm gears are of different number of teeths (one with 100 teeth, and one with 102 teeth). What is the reason for this? And it seems to me that when the pair of worm gears are glued togather. And when the pinion rotate, there may be a mismatch of gears' teeth...(one with 102 teeth, one with 100 teeth) Could you address me the problem?

    Thridly, the pair of gears are designed a bit different from ordinary spur gear, right? There is some inclination of the gears so that when they are glued togather, the entire gear looks like a "turbine" as showed in the last figure.
    What is the reason for this?

    Sorry that I am really an idiot in the stuff. Thanks for your nice help!

    Attached Files:

    Last edited: Sep 4, 2005
  2. jcsd
  3. Sep 5, 2005 #2
    can anyone help?
    Is that I decsribed the probelm too badly?
    If yes, please point out where you think the problem is vague, and I would clarify them.
    Please kindly help.
  4. Sep 5, 2005 #3


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    Hi Stephen, The first time I looked at this post, only the first drawing showed up. The last two didn't show up, perhaps you added them with the edit. But in any case, it seems a bit more clear with those pictures.

    The last picture you have shows some kind of counting or indicating mechanism. I suspect the two gears, though on the same axis, are able to rotate at different speeds such that the one with 102 teeth rotates a counter or indicator at a rate 2/100% more quickly or 2% faster than the slightly smaller gear. Note that for a very small difference in the number of teeth such as this, the gears must be 'sloppy' enough to allow for that small difference such that they turn at different speeds.

    What is the indicator on the side of the mechanism shown in your third picture for? I would guess that has everything to do with why the two gears are different.

    Note that I'm assuming the two gears rotate at different rates, so you can't "glue" them together. But the reason these gears have a slight angle cut to each tooth (they look like turbine blades) is so they can match the worm gear that's rotating them. This angle allows the gears to contact over an area as opposed to at a point which would be what would happen if the gears had a straight cut.
  5. Sep 5, 2005 #4


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    Without seeing the mechanism itself, it's hard to say. Since you've cut off half of the drawing that identifies all of the BOM components, I am assuming that the two gears in question are located directly behind the counter face? It's not very clear.

    If you have any other prints, please post them.
  6. Sep 5, 2005 #5

    yes. The two gears are directly located behinr the counter face.
    Please refer to the new thread I've created.
  7. Sep 5, 2005 #6
    yes. I see what you say now. Thanks.
    But could you refer to the new thread created? It is a follow up of this.
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