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Hi all.
For all those who, like me, have many pneumatic cylinders, but only a
limited supply of pumps, I believe I have come up with a way to get a
source of air pressure, using a cylinder and two switches. I've knocked
a quick circuit diagram up in Paint.
<http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2114017>
The following sequence should be followed. Compress the cylinder, then
flip the switches, then extend the piston, then flip the switches. Then
repeat.
Of course, the mechanisms required to make this work may well make this
too big to be useful, but you could hook up many cylinders in parallel
to increase ariflow, and if it's the only source of air that you have... :-)
I haven't yet had the chance to actually build this, as all my
pneumatics are currently engaged in other projects, but I can't see any
reason why it wouldn't work. The only thing that's bothering me is that
it seems so simple, yet I've never seen it before.
If someone knows of any reason for this not to work, please let me know.
Play on.
Owen.
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In lugnet.technic, Owen Dive wrote:
> Hi all.
> For all those who, like me, have many pneumatic cylinders, but only a
> limited supply of pumps, I believe I have come up with a way to get a
> source of air pressure, using a cylinder and two switches.
I think a much better solution would be to combine an old red "low friction"
cylinder with the old one way air brick.
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In lugnet.technic, Owen Dive wrote:
> Hi all.
> For all those who, like me, have many pneumatic cylinders, but only a
> limited supply of pumps, • [...]
> If someone knows of any reason for this not to work, please let me know.
> Play on.
> Owen.
Pumps are cheap- way cheaper than cylinders. Just buy a few. You could get three
for the cost of a case of bottled water. The price of dinner in a nice
restaurant will get you a half dozen or more (depending on where you eat).
And/or get some little pumps and a motor, and build yourself a Hempel
compressor, so you don't have to mess around with pumps.
Just Sayin',
Tim
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Tim (Smith) wrote:
> And/or get some little pumps and a motor, and build yourself a Hempel
> compressor, so you don't have to mess around with pumps.
OMG. Is that what they are calling it now?
Cheers, Ralph Hempel
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In lugnet.technic, Ralph Hempel wrote:
> Tim (Smith) wrote:
>
> > And/or get some little pumps and a motor, and build yourself a Hempel
> > compressor, so you don't have to mess around with pumps.
>
> OMG. Is that what they are calling it now?
>
> Cheers, Ralph Hempel
Hehehe.
I built one a couple years ago and have never taken it apart because it works so
well -- the design is great. I keep it on hand as my pure-LEGO compressor.
Once in a while I forget this and try to find my "missing" 9V motor. :)
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In lugnet.technic, Ralph Hempel wrote:
> Tim (Smith) wrote:
>
> > And/or get some little pumps and a motor, and build yourself a Hempel
> > compressor, so you don't have to mess around with pumps.
>
> OMG. Is that what they are calling it now?
>
> Cheers, Ralph Hempel
You didn't know?!?
It's a famous thing, man! Even Dr. Soh calls his variant a 'modified Hempel'.
There's also a four-pump version, the Quad Hempel. It's all over the web- you're
worldwide, baby!
And, while you're reading this, let me say thanks. Your compressor and limit
switch design have saved me hours of work. I use it all the time.
Tim
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In lugnet.technic, Timothy P. Smith wrote:
> In lugnet.technic, Ralph Hempel wrote:
> > Tim (Smith) wrote:
> >
> > > And/or get some little pumps and a motor, and build yourself a Hempel
> > > compressor, so you don't have to mess around with pumps.
> >
> > OMG. Is that what they are calling it now?
> >
> > Cheers, Ralph Hempel
>
> You didn't know?!?
> It's a famous thing, man! Even Dr. Soh calls his variant a 'modified Hempel'.
> There's also a four-pump version, the Quad Hempel. It's all over the web- you're
> worldwide, baby!
>
> And, while you're reading this, let me say thanks. Your compressor and limit
> switch design have saved me hours of work. I use it all the time.
>
> Tim
I also have one Hempel compressor around i never put apart. I must say is the
only one lego model i never put apart. Thanks Ralph!
Patrick
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Well I've just built this, and I can say that with a minor modification
the pump works fine.
You need to join the outputs from the two switches depicted through a
third switch to prevent pressure being lost through the exhaust port.
However, since there is no one-way valve anywhere in the system, pumping
becomes harder and harder as the air pressure builds up.
It actually pumps about the same air as a hand pump for a given number
of cycles, even though the cylinder is pumping on the up-stroke as well
as the down-stroke, but the extra effort required to flip 3 switches
would make it less efficient.
In short, while a cylinder, 3 switches and the required lengths of
tubing would be more expensive than a pump, (or possibly even a couple
of pumps), it's nice to know that I've got something that I can use,
even if all my pumps break.
Play on.
Owen.
Owen Dive wrote:
> Hi all.
> For all those who, like me, have many pneumatic cylinders, but only a
> limited supply of pumps, I believe I have come up with a way to get a
> source of air pressure, using a cylinder and two switches. I've knocked
> a quick circuit diagram up in Paint.
>
> <http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2114017>
>
> The following sequence should be followed. Compress the cylinder, then
> flip the switches, then extend the piston, then flip the switches. Then
> repeat.
>
> Of course, the mechanisms required to make this work may well make this
> too big to be useful, but you could hook up many cylinders in parallel
> to increase ariflow, and if it's the only source of air that you have...
> :-)
>
> I haven't yet had the chance to actually build this, as all my
> pneumatics are currently engaged in other projects, but I can't see any
> reason why it wouldn't work. The only thing that's bothering me is that
> it seems so simple, yet I've never seen it before.
>
> If someone knows of any reason for this not to work, please let me know.
> Play on.
> Owen.
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