Pumping with pneumatics?

[greencactus3]

Originally Posted by Billfred

I was thinking about the operation of the cylinders, and it hit me. If you connect two cylinders at the lower port with one extended, then push on it, the other goes up. So if I were to take, say, two cylinders, connect them at the same ports, stick t-junctions somewhere in between, and put an alternating force on both (as in one is pulled up, the other's pushed down, and it rotates between the two), then I'd have myself a Lego-grade compressor, right?

actually, no. youd need a one way valve before the "t junction" on both sides. only if you do that, you won't be able to pull the cylinder out... well, LEGO leaks so you will eventually, but...
so the easy way out is, make a double acting compressor using a cylinder.
you have one cylinder. connect it as you normally would as an actuating cylinder. now push and pull the piston while turning the valve.
sorry, bad explantion.
ok, ill try another way. have you ever built a pneumatic engine?(they are quite fun)
well, now crank on the supposedly output shaft of a pneumatic engine.
there yougo. you have a nice compressor. same as an electric motor. youcan use a motor as a generator. same principle.
you cannot create or destroy energy. the law of conservation of energy or something of the sort.

oh, heres a nice site on pneumatic lego engines
http://www.nicjasno.com/
some people have actually built radial pneumatic LEGO engines too.
cant seem to find the url though.

Originally Posted by Billfred

(On a tangent, I have found out that the small pump is quite possibly the wimpiest thing in all existence. It took about a pump and a smidge on the large pump to get a large cylinder all the way out--on the small pump, it was more like twelve.)

it may be that you have side loads on the small pump. as puny as it may be, it is a very useful piece. the small pump will leak like no other if you have side loads going on it. eg) too tight of tubing will actually hurt the pump's performance