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Subject: 
Re: Pneumatics: the old and the new
Newsgroups: 
lugnet.technic, lugnet.robotics
Date: 
Sat, 2 Mar 2002 06:52:18 GMT
Viewed: 
171 times
  
Hi there, Rob

That thread led to an extensive discussion into the depths of "vacuum
storage". It would appear that storing compressed air is no problem but
'the whole concept of "storing vacuum" is a little disturbing.'

Well, you can certainly pump air into a blue air tank (using the
recommended 30-35 strokes of the new hand pump) and power your pneumatic
device from off the compressed air for say 5-6 cycles before you need to
charge up the air tank again. As a matter of fact, Mario Ferrari has
used the compressed air stored in 7 of the blue air tanks to drive
"Eolo" his Sumo robot to victory.

Now try to *store* vacuum in one or more of the blue air tanks. Stop
your pump and try to work your pneumatic device from off the "stored
vacuum". How many cycles do you think your old pneumatic based device
would work before you have to regenerate the vacuum?

It is in this context that Christophe and I said that the air tank would
not work with the old style pneumatics.

I note that your window walker has an umbilical that leads to one of the
old hand pump which I figure has to be worked continuously. So you are
not really relying on stored vacuum but have to generate it
continuously. In which case an air tank to *store vacuum* would not be
needed. I wonder if the creature may work better without the air
tanks...

Cheers!

Rob Stehlik wrote:

Hello pneumatics fans,
I have been working a lot with pneumatics lately, and have made some
interesting discoveries. I think the most notable is a method of using the
old style red cylinders with the new pneumatics system. I came across this
as I was working on a recent robot, and I wanted to minimize the amount of
air required. There was a thread not too long ago about pneumatic check
valves, creating a vacuum, etc. When I read this post:
http://news.lugnet.com/robotics/?n=16764
It jumped out at me. C.S. Soh was saying you can't use the old single acting
cylinders with air tanks. Not true! I wanted to reply, but I didn't have any
pictures up on my site at the time, so I have waited until now. Anyway, have
a look:
http://www.ecf.utoronto.ca/~stehlik/ideas.html
On the pneumatics page, you will also see some unusual compressor designs
and a valve switching unit that controls two valves with one motor.
Eventually I would like to make Ldraw instructions for this unit, as it is
very useful and reliable. You can see an application of the single acting
cylinder here:
http://www.ecf.utoronto.ca/~stehlik/projX.html
Oh yeah, this is old news, but if you want to see an application of vacuum
tanks, see my window walker:
http://www.ecf.utoronto.ca/~stehlik/wwpics.html
Enjoy,
Rob

--
C S Soh

CSSoh's Lego Pneumatics
http://www.geocities.com/cssoh1
... where air is power!



Message has 2 Replies:
  Re: Pneumatics: the old and the new
 
(...) Now things get a little philosophical :) The air tank itself has no idea about vacuum or pressure. The only thing the tank stores is a pressure difference. The difference between the outer pressure and the inner presure. This difference might (...) (23 years ago, 2-Mar-02, to lugnet.technic, lugnet.robotics)
  Re: Pneumatics: the old and the new
 
"c s soh" <cssoh@singnet.com.sg> wrote in message news:3C8076A2.E27D98....com.sg... (...) You most certainly can store vacuum. How would a TV set work, otherwise? When the tube is finally smashed or broken at the end of it's life, the vacuum (...) (23 years ago, 3-Mar-02, to lugnet.technic, lugnet.robotics)

Message is in Reply To:
  Pneumatics: the old and the new
 
Hello pneumatics fans, I have been working a lot with pneumatics lately, and have made some interesting discoveries. I think the most notable is a method of using the old style red cylinders with the new pneumatics system. I came across this as I (...) (23 years ago, 1-Mar-02, to lugnet.technic, lugnet.robotics)

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