Subject:
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Re: I wish Lego made an "Anti-Backlash Gear"
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Newsgroups:
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lugnet.robotics, lugnet.technic
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Date:
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Thu, 5 Apr 2001 05:16:40 GMT
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Viewed:
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3740 times
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Interesting , but we need one for Lego! I do see what you are saying, and
It is an interesting solution,, although a little hard to visualize...Thanks!
In lugnet.robotics, Thomas D. Fulk, Jr. writes:
>
>
> > Tech question for us: Any body know what an Anti-Backlash gear
> > is? If Lego made one, we would all have super precise Robots and
> > mechanisisms! BERG carries them... Anybody know what I'm talking
> > about?
>
>
>
> I know of 1 type of zero-lash/anti backlash geartrain.
>
>
> It's hard to put it in words but I'll try. My example assumes there
> are only 2 shafts but it can be applied to as many shafts as you
> need.
>
>
> In my example S1 represents our first shaft. Drive or driven, you
> choose. result is the same. S2 represents the other shaft in our
> gear train. G1and G2 are 2 separate gears on S1, and they are both
> in mesh with G3 which is located on S2. G2 is not splined to S1 like
> G1 is, and is only there to act with the spring to remove the lash.
>
> Now.... Our first gear is actually 2 thin gears (G1 and G2)
> together on the same shaft (S1), working as 1 gear... mating to a
> single thicker gear (G3) with a torsional spring force causing G1 and
> G2 to rotate in opposing directions, except the teeth of G3 stop them
> from rotating more than the lash between the G1/G2 pair and G3.
> Really the G1/G2 pair is acting a variable pitch gear that perfectly
> mates to G3 at all times.
>
> If the force required to move the load is more than the spring
> force between G1 and G2 there can be lash in this setup. In the
> real-world application where I have seen this used (Toyota 3.4 V6
> engine, to mate the two camshafts located in each cylinder head) there
> is a way to lock G1 and G2 together before you separate them from G3.
> I assume this is because the spring is so strong that it would be hard
> to rewind in the field.
>
> Thomas
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