Subject:
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Re: micro motor jam
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Newsgroups:
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lugnet.technic
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Date:
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Sun, 16 Apr 2000 19:28:14 GMT
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Viewed:
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864 times
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> When I took a jammed micromotor apart... What I did find was that the internal • gears
> use very small teeth, but there was enough freeplay in the gears'
> rotational axis that it was easy to get the gears misaligned (therefore
> jamming them).
> Cheers,
> Henry C.
I haven't taken my micromotor all the way apart, just popped the face off. But
from my cursory investigation it appears that the micromotors use an unusual
arrangement of gears, which I think is called a planetary gear. As far as I
know, the freeplay is actually intentional. The white gear that is closest to
the face of the motor is attached by an axle to a gear nearly the same size,
but with perhaps one or two more teeth. The two coaxial gears both mesh with
separate "inside-out" gears like the one attached to the face of the micro
motor housing. The axis of these two gears is actually a little bit off
center, and the motor itself moves that axis around in small circles by way of
a little off-center pin. The two coaxial gears "walk" around the inside of
their respective inside-out gears, and because they have slightly different
numbers of teeth, the two inside out gears have to rotate with respect to each
other. If the coaxial gears differ by one tooth, then every rotation of the
motor causes the face to turn one tooth's distance.
It's really groovy, but the small teeth do tend to jam. Maybe a bit of
lubrication would help the gears not to catch. I'd be really psyched if Lego
would start making more different kinds of gears so we could play with unusual
arrangements like this. Some inside-out gears would be neat, maybe some clutch
and dog mechanisms. Then I might figure out what all those gears are really
called.
-Phil
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Message has 1 Reply:
 | | Re: micro motor jam
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| (...) Yeah, I think they should be called planetary gears too, but I am just about as sure as you are... The gears are supposed to move in a certain fashion, but their fit is so loose that it is easy for the teeth of the gears to step on top of each (...) (25 years ago, 16-Apr-00, to lugnet.technic)
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Message is in Reply To:
| | Re: micro motor jam
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| (...) When I took a jammed micromotor apart, I could not find any thermal cutoff circuitry at all. What I did find was that the internal gears use very small teeth, but there was enough freeplay in the gears' rotational axis that it was easy to get (...) (25 years ago, 13-Apr-00, to lugnet.technic)
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