 | | Pneumatic Questions —Andrew Meyer
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| | | I am comtemplating the purchase of one of those one-way valves from the old pneumatic sets. I was wondering, if you set up a system in which one tank was pressure and one was vacuum, and applied both to a 2-cyl engine, would it turn with more power (...) (19 years ago, 17-Nov-05, to lugnet.technic)
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| | | | | Re: Pneumatic Questions —Kevin L. Clague
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| | | | | (...) This is a good question. When using traditional pressure only, the force producde by the air pressure on the faces of the pistons is enough to flip a switch. Just yesterday someone asked me "If instead of using pressure, you used vaccume" (...) (19 years ago, 17-Nov-05, to lugnet.technic)
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| | | | | | | Re: Pneumatic Questions —Nathan Bell
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| | | | | | | (...) Just out of curiosity, how would one go about creating a continuous vaccume? A temporary one can be created inside a piston by clogging one end, but how could one create a continuous vaccume? Would this need to be done in, say, an accumulator (...) (19 years ago, 17-Nov-05, to lugnet.technic)
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| | | | | | | | | Re: Pneumatic Questions —Nathan Bell
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| | | | | | | | | (...) Never mind. I just figured out the answer to my own question. It was an easy one. (19 years ago, 17-Nov-05, to lugnet.technic)
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| | | | | | | | | | | Re: Pneumatic Questions —Chio Siong Soh
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| | | | | | | | | | (...) Did you? Was it? Haha, I recall there was a long discussion on vacuum not a long time ago. CSSoh (19 years ago, 18-Nov-05, to lugnet.technic)
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| | | | | | | | | | | | Re: Pneumatic Questions —Kevin L. Clague
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| | | | | | | | | | (...) Hi Dr. Soh, Nice to hear from you. I've never actually built with the original pneumatics, but my understanding is that the way to use switches in the old pneumatics is different than the way you use them with dual ported pistons. Don't you (...) (19 years ago, 18-Nov-05, to lugnet.technic)
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| | | | | | | | | | | | Re: Pneumatic Questions —Chio Siong Soh
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| | | | | | | | | | (...) Thanks, Kevin. Had to break-in as matters seem to be getting outta hand. It appears we're getting a new generation of pneumatic fans. Great! (...) No, you use them the same way. The pneumatic switch is basically a directional control valve. It (...) (19 years ago, 19-Nov-05, to lugnet.technic)
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| | | | | | | | | Re: Pneumatic Questions —Steve Dunn
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| | | | | | | | (...) The older style pumps didn't have a built in waist valve. (URL) If you connect an older pump to your compressor, then a hose from the pump to the centre port of the 2x4 "distribution block", (URL) one of the other ports (i can't remember which (...) (19 years ago, 18-Nov-05, to lugnet.technic, FTX)
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| | | | | | | Re: Pneumatic Questions —Chio Siong Soh
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| | | | | | (...) Just so. (...) No, it wouldn't walk backwards. To make it work, you'd only have to interchange the hoses at the switches. That's because a suction force acts in the opposite direction to the traditional compressed air. Your walker will then (...) (19 years ago, 19-Nov-05, to lugnet.technic, FTX)
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| | | | | Re: Pneumatic Questions —Chio Siong Soh
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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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| | | | | | Re: Pneumatic Questions —Andrew Meyer
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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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| | | | | | Re: Pneumatic Questions —Chio Siong Soh
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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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| | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | | Re: Pneumatic Questions —Chio Siong Soh
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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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| | | | | | | | Re: Pneumatic Questions —Billy Bauman
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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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| | | | | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | | | | | Re: Pneumatic Questions —Geoffrey Hyde
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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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| | | | | | | | | | Re: Pneumatic Questions —Chio Siong Soh
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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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| | | | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | | Re: Pneumatic Questions —Chio Siong Soh
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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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| | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | Re: Pneumatic Questions —Chio Siong Soh
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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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| | | | | | Re: Pneumatic Questions —Kevin L. Clague
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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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| | | | | | Re: Pneumatic Questions —Technex
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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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| | | | | | Re: Pneumatic Questions —Mark Bellis
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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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| | | | | | Re: Pneumatic Questions —Ignacio Martinez Vazquez
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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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