Subject:
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Re: gear differential
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 18 Nov 1998 21:37:26 GMT
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Viewed:
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2246 times
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I have used rubber bands in some of my models. I have found that the Lego
belts (I call them V-belts) have very different properties from your average
rubber band (and the Lego rubber bands found in for e.g. Mud Masher).
Some things I have seen:
The V-belts quickly loose elasticity after a short elongation -- relative to
a regular rubber band. The stretch is just accommodating enough to fit
multiple applications, and to allow over lap between the different sizes of
V-belts. When stalled, the v-belt quickly becomes a "cord" with little
elasticity. To increase the power that the V-belt can transfer you should
use the pulleys. Pulleys will seat the V-belts and increase the surface
area that the V-belts make with the drive system. Rubber bands are
particularly poor at this because they are square and the seat of the
pulleys are round. Using just a axle or hub to drive a V-belt will provide
much less friction (which maybe is what you want?).
The disadvantage (or advantage depending on application) is the slop of
having the bands contract and elongate when changing direction or coming
under an increased load. Not a big concern in most applications, because
the right size v-belt will minimize the slop.
You might also find that systems using lower rotational speeds will "break
free" less
I have a model that will have 6 knobby balloon tires break free on a
semi-rough surface before the V-belts will. I think this is because of
using pulleys, low speed, and proper sized V-belts (and the model is kinda
light too I guess).
Anyway,
LINC
Matthew Miller wrote in message ...
> Dave Forrest <davef@shmoopie.com> wrote:
> > I saw this picture of a Limited Slip Differential yesterday:
> > http://home.sol.no/~selode/lego/limited.html
>
> I don't understand how people use rubber bands like this in projects --
> they never seem to transmit enough power to move anything reliably.
>
> --
> Matthew Miller ---> mattdm@mattdm.org
> Quotes 'R' Us ---> • http://quotes-r-us.org/
>
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