Subject:
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Re: My Lego planetary gear
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Newsgroups:
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lugnet.technic
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Date:
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Wed, 4 Oct 2000 04:19:43 GMT
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Viewed:
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1067 times
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You can actually get very similar behaviour using a standard differential.
If you hold one "output" shaft, and turn the other, the crown wheel turns at
half the input speed. The advantage of planetary gears is the output shaft
is in line with the input shaft, making it easier to chain them together. A
lot of old cars used this technique - the output of the first was connected
to the outer ring of the second, and so on. Locking the last one in the
chain gives you low gear, locking the next gives you a higher gear (by
"reducing the reduction") and so on. Big advantage of this technique is
there's no real need for a clutch.
Regards,
ROSCO
Amnon Silverstein <amnon@best.com> wrote in message
news:G1vopu.J1C@lugnet.com...
> By locking the outer ring, in acts as a 2:1 or 1:2 gear (depending on • which
> shaft you use as input and which as output. If you lock the planets, it • turns
> into a 1:1. If you let everything loose, it is a neutral gear. If you lock • the
> output shaftand tap off of the ring somehow, it could act as a reverse, • but in
> practice this has a few problems. The planets and the sun gear tend to jam • and
> the gear drag is pretty bad.
> Yeah, if Lego made some real parts for this, it would be much easier to • rig up
> a multi-speed transmission with reverse.
> This works well enough to demonstrate the principles of a planitary gear
> system, at least.
>
> In lugnet.technic, Geoffrey Hyde writes:
> > That is certainly compact. Do you have any ideas how it might be used in • an
> > actual model? I suppose locking either the top half or the bottom half, • or
> > both, would change the way the output shaft differs from the input shaft?
> >
> > Although what I would really like to see is an inner gear ring which is a
> > lot larger than the current gears are. I'm not sure if it's technically
> > feasible to make, though!
> >
> > Cheers ...
> >
> > Geoffrey Hyde
> >
> >
> > Amnon Silverstein <amnon@best.com> wrote in message
> > news:G1u5JH.BMp@lugnet.com...
> > > I was working on transmission ideas, and I came up with a cute • planetary.
> > It
> > > can produce several different types of output, and it is typically used • in
> > > transmissions. My implementation is compact, and doesn't use too many • parts.
> > > I'm not sure that it is useful for anything, but it might be cool in a
> > > gearhead-nerd way.
> > >
> > > http://www.best.com/~amnon/Homepage/Games/PlanetMiddle.jpg
> > > http://www.best.com/~amnon/Homepage/Games/PlanetTop.jpg
> > > http://www.best.com/~amnon/Homepage/Games/PlanetBottom.jpg
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Message has 1 Reply:
 | | Re: My Lego planetary gear
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| Ah. Hm, I wonder if it could be used for a lego transmission. I cleaned up my first planetary gear, and I came up with a second implementation. It is bigger, and it is not obviously a planetary system, but I think it is topologically equivalent. It (...) (24 years ago, 4-Oct-00, to lugnet.technic)
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Message is in Reply To:
| | Re: My Lego planetary gear
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| By locking the outer ring, in acts as a 2:1 or 1:2 gear (depending on which shaft you use as input and which as output. If you lock the planets, it turns into a 1:1. If you let everything loose, it is a neutral gear. If you lock the output shaftand (...) (24 years ago, 3-Oct-00, to lugnet.technic)
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