Subject:
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Re: Pneumatic steering (was Re: Suspension)
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Newsgroups:
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lugnet.technic
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Date:
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Sun, 3 Apr 2005 19:47:16 GMT
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Viewed:
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4542 times
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In lugnet.technic, Maarten Steurbaut wrote:
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I am currently trying to build a vehicle with pneumatic steering.
Pneumatic steering:
* If you move the lever on your control-unit slightly to the left/right, the
vehicle will make a wide turn left/right.
* If you move the lever on your
control-unit completely to the left/right, the vehicle will make a short turn
left/right.
* If you release the lever (bring it back in center position),
the vehicle moves straight forward again.
This doesn’t happen with Lego
models (e.g. the distance guided vehicle from set 8082). If you want this
vehicle to move straight forward again, you have to move the lever in the
opposite direction first (and bring it back in neutral at the correct
moment).
I accidentally ran into this LUGNET-post:
SNIP
If you
move the lever on the control-unit to the left/right, the pumps will go
left/right until the second valve is actuated. As long as you keep the lever
to the left/right, the pumps will stay in this position. Once you bring the
lever back in neutral position the pumps will move right/left until the
second valve is also back in neutral position (it doesn’t stop exactly in the
middle, but it comes pretty close).
But this does not solve my problem: I
want the pumps to stop in any possible position (the further the lever goes,
the further the pumps go).
And then I came up with this:
Moving
the first one to the left will cause the second one to move to the left too.
It works well with short hoses, but it gets tricky if you use longer hoses (I
want to hold my control-unit at least at 1.5m distance).
Because LEGO
doesn’t have one-way-valves (yet), I need two seperate input-lines to prevent
air from flowing from one line to the other (with a no-pressure situation as
a result). This would require two “pressure valves” (as seen in Jennifer
Clarke’s control-unit) and a very big control-unit.
However, there’s another
problem: every now and then I hear a “PFWT” (air escapes through one of the
valves) and both cylinders are no longer aligned. Re-aligning is done best if
both cylinders are in outer position, so I have to pick up the vehicle every
time this happens (and it happens too often in my opinion...).
Anyone out
there working on something similar but with better results so far??
Maarten
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The ways to get round your last issues are:
Use flex tubing for most of the long tubes - this eliminates the balloon effect.
You can get one-way valves from Big Ben Bricks:
http://www.bigbenbricks.com/pneumatics/pneumatics.html
With sudden movements you will still get air escaping though.
Mark
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Message is in Reply To:
 | | Pneumatic steering (was Re: Suspension)
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| I am currently trying to build a vehicle with pneumatic steering. Pneumatic steering: If you move the lever on your control-unit slightly to the left/right, the vehicle will make a wide turn left/right. * If you move the lever on your control-unit (...) (20 years ago, 3-Apr-05, to lugnet.technic, FTX)
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