Re: permanent magnet motor

In sci.physics, Sam Wormley
<swormley1@xxxxxxxxx>
wrote
on Sun, 18 Feb 2007 14:23:26 GMT
<yjZBh.2164$PD2.1866@attbi_s22>:
gdewilde@xxxxxxxxx wrote:

So far you guys quoted me the laws of physics over and over again.



Don't you know the laws of physics?


State the laws mathematically as they apply to your device, Gaby!
Wethinks you can't.


It would help if he more completely specified his device.
I see two discs and 5 magnets thereon; there's no
indications as to whether they are geared or not (it's dead
either way so it doesn't matter all that much). Nor is
it clear whether the one wheel is positioned exactly in
the plane of the other's axis, or if there's an offset.

None of this matters, though; Stevin's Principle applies
throughout if they're 1:1 geared, no matter what the
positioning. If they're geared to some other ratio
it probably won't work even in gdewilde's thinking.
If they're not geared at all the moment in the one wheel
will be smaller than the other (a *lot* smaller if the
actual wheels are thin and lightweight, relative to the
magnets) and it will spin to an equilibrium position,
producing a tiny amount of work until everything gets stuck
in an attract-attract position. If the discs are carefully
weighted so that they have exactly the same moment (by
using identically-weighted lumps of non-magnetized metal
in the appropriate places on both discs), it might stand
a chance of working -- for a very short while.

Hero's toy engine might have looked sillier but at least it
worked, and had a very readily identifiable power source --
namely, the fire underneath it.

http://en.wikipedia.org/wiki/Aeolipile

(The modern classrom variant looks even sillier. :-) )

It is barely possible that this is not a PPM but a
transference problem; the green disc might be spun by an
external power source, and the blue disc would extract
power therefrom. Such would be a rather odd form of
magnetic clutch; better coupling would probably be had
by simply using two wheels, one smaller than the other,
both with four magnets pointing north-south (from axis
to circumference).

It might even work better with electromagnets, where the
current can be cut off to allow the device to freespin
to a stop.

Whether these are more practical than the current
mechanical or fluid clutch designs is far from clear; since
we're using fluid clutches now (in automatic transmissions)
I'd say no.

It's worth noting that strong but tiny magnets are
easily available, at least from the pages Google
coughs up. The tiny spheres can easily lift a 15 inch
metal spanner/wrench, plus an assortment of other tools.
The author then gets into a (apparently rather messy but)
interesting description of ferrofluid and ferrofilm.

http://www.dansdata.com/magnets.htm

Building a model would not be a problem, though I don't
know what kind of glue would be required to keep the
magnets from flying off what presumably would be
a wooden disc.

--
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Windows. When it absolutely, positively, has to crash.

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.

Relevant Pages

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