Subject:
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Re: pneumatics & mindstorms?
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 28 Jul 1999 20:20:47 GMT
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Viewed:
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1241 times
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> In lugnet.robotics, Joel Shafer writes:
> > I built a compressor with the large pump with the spring removed. It
> > worked but it was too slow . It took 3-4 minutes before enough pressure
> > was available to open a big piston just once. The compressor had to be
> > geared very slow to provide enough torque to operate.
After the big piston operates once, how long does it take to recharge the
pressure?
In lugnet.robotics, Mario Ferrari writes:
> I had exactly the same experience. I used that kind of compressor on my S5
> robot many months ago, it's slow and unefficient.
> The small pumps work much better. Ralph Hempel has a very good double action
> compressor in his page:
I did not build a compressor using the large pumps before, only the small
pumps, so I believe in your findings. Still I wonder why.
The larger pump takes more force to move than the smaller pump, but the larger
pump also pushes in more air per stroke than the smaller pump. There must
something other than the sizes that causes the difference in efficiency.
(Friction?)
The tank pressure is not constant. Maybe we need an automatic transmission: We
switch to the lower gears when the pressure is built up. (I think this is too
complicated for being practical. Still, an interesting thought.)
Maybe we should use something like a balloon as the tank. The volume of the
Lego tank is not expandable, therefore within one or two operations, the
pressure goes down quickly while there are still lots of air in the tank. As
the result, the actual usable volume of the Lego tank is only a fraction of
its total volume.
Just some random, untested thoughts.
Cheers,
Hao-yang Wang
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Message has 1 Reply:
 | | Re: pneumatics & mindstorms?
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| (...) Yes, I guess friction is the answer. 1) The difference in the surface of the pistons between the two kind of pumps is important. I didn't compute the ratio, but imagine can easily be 1:10 or even more. To get that ratio you need to gear down (...) (25 years ago, 29-Jul-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: pneumatics & mindstorms?
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| (...) I had exactly the same experience. I used that kind of compressor on my S5 robot many months ago, it's slow and unefficient. The small pumps work much better. Ralph Hempel has a very good double action compressor in his page: (URL) like his (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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