Pumping with pneumatics?

[Billfred]

I checked out that site--if I can figure out how to make that four-cylinder engine into a three (a lego geo metro--who knew?), then I bet I'll be hot to proverbially trot.

And I don't think that there were any side loads on my small pump. I could be wrong, though.

[Alex Pelan]

Yeah...we used two cylinders to create a vacuum as well. Originally, it was going to power three suction cups on our arm so that we could handle all 3 2X balls, however, we ended up having to take our arm off due to center of gravity issues/driver inexperience with this arm. So, we were left with the vacuum only powering the shifter.

[greencactus3]

Originally Posted by Billfred

if I can figure out how to make that four-cylinder engine into a three (a lego geo metro--who knew?), then I bet I'll be hot to proverbially trot.

a 3 cylinder may be a little harder because a 90 degree angle is more often used in LEGO pieces than a 60 degree. of course there are propellers, and rotors, pulleys and wheels, angle beams and universal joints...etc,, using lego, a 4 cylinder pneumatic engine may actually be more compact than a 3 cylinder. definitly easier to make. also the timing of the valves would be a little harder. with a 2 or 4 or 8 cylinder, the valve timing just needs to be half rotation, quarter rotation, eighth rotation off. i think thats easier than a one third off.

[Billfred]

Touché. This is why I don't design engines for a living.

Anyone got a spare large cylinder? (grin)