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 Technic / 14882
14881  |  14883
Subject: 
Re: Random Pneumatic idea/question
Newsgroups: 
lugnet.technic
Date: 
Tue, 22 Nov 2005 20:52:52 GMT
Viewed: 
9902 times
  
In lugnet.technic, Billy Bauman wrote:
> In lugnet.technic, Billy Bauman wrote:
> > In lugnet.technic, Kevin L. Clague wrote:
> > > In lugnet.technic, Billy Bauman wrote:
> > > > 
> > > >   Speaking of liquids, Is it possible to replace the air in the pneumatic system
> > > > to make a hydraulic system. I mean by using something like, oh say, 10 WT
> > > > silicone oil?
> > > > 
> > > >   http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX3297&P=7
> > > > 
> > > >   I guess not since you can't complete the circuit because of the inability to
> > > > access the exhaust port on the valves or the intake on the pumps.
> > > 
> > > Yes, the fourth port is an issue.  It is possible to hook multiple switches to
> > > give you access to the fourth port though.
> > 
> >   Is it now? Hmmmmmm. How would one go about hooking these switches to access
> > the
> > fourth port? Is there a website that I can visit that would give a good
> > explanation to this?
> > 
> >  With thanks,
> >   Billy.
> 
>   An interesting thing has happened. after asking about how one sets up the
> switches to access the fourth port, I decided to sit down and figure out how to
> do it myself. Initial progress was slow and I don't have any pictures of it,
> however, I was able to figure out how to do it. Afterwards, I went on the posts
> to see if anything came up, and I found this.
> http://news.lugnet.com/technic/?n=14861
>   Turns out that my findings were similar to Kevin's schematic. Like his, I
> used 4 Switches, and 4 T pieces. In order to pump the fluid in the system
> without loosing or adding any fluid, I decided to use a pneumatic ram as my
> pump, by using the two ports on the cylinder as the intake and output. When two
> of the switches are open and two are closed, and I push the ram, the fluid in
> the system cycles through in a clockwise direction. The problem comes in, that
> if I pull the ram back up, it draws the fluid back through the system in a
> counterclockwise direction. So the valves are set up such that when I close the
> first two valves, and I open the second two valves, the connections of the
> ram/pump are essentially reversed, and thus pulling the ram pushes the fluid
> through the system in a clockwise direction while also containing the fluid in
> the system and without letting any extra fluid in, which is the key, I believe
> to hydraulics. The really strange things is that, having figured out how this
> works, I'm amazed at how simple it actually is.
>   I assume then, that the load on the system would work in much the same manner,
> as a way of keeping the fluid in the system while also reversing the direction
> of the system. (That is, reversing the direction of the load, wile maintaing the
> constand direction of the main system.)
>   The main reason for the post is that, having constructed the system, it
> appears to be valid, however, I wouldn't mind having a confirmation on my
> findings.
> 
>  Sorry if I'm a bother,
>       Billy.

Hi Billy,
  Well, my recollection of a composite five port switch was faulty.  When I
tried to create a two piston timing circuit (precursor to motor), it would leak
because all four switches would be on, letting pressure directly through to
exhaust.

  I realised the safest way to achieve something hydraulic, and pressure+vacuum
capable was to make sure the composite switch had an off position.

  http://news.lugnet.com/technic/?n=14881

  The pressure vacuum mechanism works, and should give a pneumatic device more
power.

  I have not tried to use the composite switch for hydraulics though.

  If I were to implement something hydraulic, I would want hose clamps.  While
LEGO doesn't make these specifically, a piston port with hose over it is about
the same diameter as a technic pin hole.  Others have suggested using those as
hole clamps.

  I have another idea for a smaller composite switch, using a lever arm with a
gear, twisting a differential.  The two outputs of the differential would flip
switches.  There would be a mechanical stop to prevent the switches from using
both outside ports.  Also rubber bands would be used to tension the switches in
a way where the differential would move first one switch, and then the other.
If you get my meaning, go ahead and give it a try.

  Keep us informed on your building progress.

Kev



Message is in Reply To:
  Re: Random Pneumatic idea/question
 
(...) An interesting thing has happened. after asking about how one sets up the switches to access the fourth port, I decided to sit down and figure out how to do it myself. Initial progress was slow and I don't have any pictures of it, however, I (...) (21 years ago, 21-Nov-05, to lugnet.technic)

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