Subject:
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Re: Suspension
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 17 Aug 2004 16:01:03 GMT
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Viewed:
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3710 times
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In lugnet.technic, Andrew G. Meyer wrote:
> In lugnet.technic, Vineet Honkan wrote:
> > Andrew-
> >
> > You have a nice idea, but the problem I see with it is that there is no digital
> > counter to measure the distance of the piston at its starting point. Here's a
> > link to a pretty neat website about air suspension:
> >
> > http://www.air-suspension.co.uk/
> >
> > Are you looking for ground clearance in your vehicle?
> I'm not actually building a vechicle at the moment. I was just wondering how it
> could work, because many sites list pneumatic cylinders as "large shock
> absorbers."
>
> Andrew
With Lego pneumatic parts it would be different from the real thing, since Lego
cylinders are to coarse in operation, with to much friction to be able to stop
accurately at a given position with a given air pressure.
However, the way to do it would be to set a pneumatic valve to switch at the
correct point. I have successfully got a pair of cylinders to stop in the
middle of their travel, the application being pneumatic steering for a JCB.
To do suspension I would probably use a threaded axle to give variable
calibration of the valve set point.
My steering system uses a pair of valves to command the position (left, right or
centre, or for suspension up, down and normal height), with three valves being
connected to the cylinders. I use antennas as stoppers in some tubes, one on
each of the outer valves in a line of 3. The 3 valves have their levers offset
in order to switch at different points.
The idea is to apply pressure to both sides of the cylinders equally at the
correct height, but if the cylinder is displaced either way by a small amount
the pressure to one end will cut off and it will self-centre again. In the
centre the middle valve is in its centre off position, but both outer valves are
just on. Moving either way one of the outer valves cuts off and moving further
the centre valve opens.
For suspension you might need to apply spring power equal to the body weight on
each wheel, in order that equal air pressure at each end of the cylinder will
set the suspension to its normal height. This might be achieved with elastic
bands pulling the suspension to the fully extended position.
The steering system works best when moving from one end to the centre, rather
than from a slight offset to the centre, due to the friction.
Mark
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Message has 1 Reply:
 | | 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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Message is in Reply To:
| | Re: Suspension
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| (...) I'm not actually building a vechicle at the moment. I was just wondering how it could work, because many sites list pneumatic cylinders as "large shock absorbers." Andrew (20 years ago, 17-Aug-04, to lugnet.technic)
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