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(...) Sort of like a DPDT reversing switch arrangement? However, if you study how the LEGO pneumatic valve is built you know it's not going to work. Namely, it has a fourth exhaust port that's inaccessible. You'll have to plug up this port for your (...) (19 years ago, 18-Nov-05, to lugnet.technic, FTX)
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In lugnet.technic, Andrew Meyer wrote: "...if you set up a system in which one tank was pressure and one was vacuum, and applied both to a... 90d phase shift 2 cyl engine... so that when one side of a cylinder had pressure applied, the other would (...) (19 years ago, 18-Nov-05, to lugnet.technic, FTX)
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(...) I'm glad if I saved you some bucks. The fourth exhaust port is a necessity (for the cylinders to work) and a nuisance (being inaccessible). I first learned about it from Erik Brok's site. In real-life pneumatics, this port would be brought out (...) (19 years ago, 19-Nov-05, to lugnet.technic)
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(...) It is possible to combine multiple switches into a release-free switch, but they would probably be more load than a single switch used on dual ported piston. Kevin (...) (19 years ago, 19-Nov-05, to lugnet.technic, FTX)
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(...) Ahhh, I would love to see it done :-) CS (19 years ago, 20-Nov-05, to lugnet.technic, FTX)
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(...) I know this sounds a little naive, but what is a release-free switch, and what would it be used for? Billy. (19 years ago, 20-Nov-05, to lugnet.technic, FTX)
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(...) Hi Billy, A LEGO pneumatic switch has four ports. You are probably familiar with the obvious three: left, center and right. The fourth port is not obvious. When you've got pressure on one port of the piston, and you switch the switch so you (...) (19 years ago, 20-Nov-05, to lugnet.technic, FTX)
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(...) I'm not at home, so I can't lookup the history on this in my LEGO notebooks. I think Doug Carlson invented this. I rederived it today, because I knew it wasn't too complicated. It involves four switches and four T's. The four switches form two (...) (19 years ago, 20-Nov-05, to lugnet.technic)
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(...) I found this picture on my brickshelf account. It shows the lego geometry needed to implement the four port switch. The hoses are not right, but the switch positions and lever linkages are correct. (URL) (19 years ago, 20-Nov-05, to lugnet.technic)
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(...) Hi Andrew, Here is a schematic for an engine that combines pressure and vaccume on both piston faces. (URL) uses the four port switch I described in this thread: (URL) The image shows a compressor and air tanks for having pressure and vaccume (...) (19 years ago, 20-Nov-05, to lugnet.technic, FTX)
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"Kevin L. Clague" <kevin_clague@yahoo.com> wrote in message news:Iq9H1s.2Ao@lugnet.com... (...) Has anyone tried to open up the pneumatic switch (old and new ones) to see if there is a way this 4th port could be vented into a tube and thus (...) (19 years ago, 21-Nov-05, to lugnet.technic)
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(...) Great! Let's see how the engine runs. CSSoh (19 years ago, 21-Nov-05, to lugnet.technic, FTX)
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(...) Been done here: ((URL) look like it's gonna be easy to modify. (...) Wish they would! BTW, I made a bummer in calling the hidden exhaust port the 'fourth port'. It should actually be port 3. In pneumatics nomenclature, the ports are designated (...) (19 years ago, 21-Nov-05, to lugnet.technic)
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(...) Andrew, It is so interesting that you broached the topic of vaacume/pressure pressure at the same time as the hydraulic question. In many ways they are the same problem. Containment. With vaccume/pressure you need a switch with containable (...) (19 years ago, 21-Nov-05, to lugnet.technic, FTX)
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(...) No - exhaust! (...) You need to eventually discharge the compressed air (or vacuum) in a pneumatic system. Interestingly enough, this is the first time I heard of a pneumatic system using compressed air and vacuum at the same time. Usually (...) (19 years ago, 21-Nov-05, to lugnet.technic)
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(...) I don't understand this statement. (...) In this compressor/engine schematic I drew yesterday, vaccume is the exhaust for pressure, and pressure is the exhaust for vaccume inside the engine. The part of the compressor that creates vaccume (...) (19 years ago, 21-Nov-05, to lugnet.technic)
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Well, I would love to have an exhaust port for my lego engines, I love messing around with the exhaust system, making different noises and so on. I've tried modding about 6 of the old valves, and no luck. Is there any other way of making a valve do (...) (18 years ago, 18-Jun-06, to lugnet.technic)
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(...) To get an exhaust that doesn't leak away the whole pressure of the system, use a small cylinder or two that pushes against some rubber bands to open a valve: (URL) the pressure leaks away, the rubber bands overcome the reducing pressure in the (...) (18 years ago, 18-Jun-06, to lugnet.technic)
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(...) (URL) guess you'll have to build them yourself. (18 years ago, 24-Jun-06, to lugnet.technic)
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