Re: Two pressures?
 

I was shooting for something like this

edit:
bah stupid formating

edit 2x:
this doesn't look right at all... must mean it's time for sleep

Re: Two pressures?
 

I understand your intent now... your clarification got sandwiched in between my read and my write. I don't know what your mechanism actually looks like, but would it be possible to leave one side of your pneumatic vented and just use a bit of surgical tubing for the extension?
I'm not sure what the technical term is, but I know I've played with cylinders that had a spring loaded extension and a pneumatic retraction. I couldn't tell you if those components are FIRST-legal, but you might be able to cobble a reasonable facimile together. Then again it might not be worth the added complexity.

Re: Two pressures?
 

that should work, but i dont know how fast the regs bleed off pressure when the air flows backward thriygh them. by puuting them before a solenoid (which requires 2 soleniods) you get a quick dump of rpessure and a MUCh quicker acting piston

But i have never tested this, the flow of air back through the reg may be suffecient for your applicatrion!

Re: Two pressures?
 

There is a way to retract the cylinder using no air at all - leave the other end of the cylinder open - no connection, and use a small spring or the surgical tubing to retract the cylinder

then you only need a single valve to pressurize the business end, and when you close the valve it will vent the air, and the surgical tubing will retract the cylinder.

Re: Two pressures?
 

I think using the single solenoid off a secondary regulator would work best. Just shorten all your tubing so it will regenerate pressure quicker. You don't need to worry about flow controls all that will do will slow down your cyclinder and not reduce amount of air used.

I think he wants to extend and then retract Ken.

edit: But I imagine it would work the other way too

Re: Two pressures?
 

GREAT POINT!!

this might be exactly what your are looking for because one way uses no gas consumption.

Re: Two pressures?
 

Yes, but unfortunately the surgical tubing doesn't provide the retracting force we need. We are trying to save air on the extend. If you look at the picture you may see more clearly why we want to save air

http://www.chiefdelphi.com/forums/sh...ad.php?t=25130

24 '' stroke if I remember right

Re: Two pressures?
 

[quote=KenWittlief]There is a way to retract the cylinder using no air at all - leave the other end of the cylinder open - no connection, and use a small spring or the surgical tubing to retract the cylinder [\QUOTE]

Gentlemen, I think we should all take a big step back from this forum for the night. I've never seen a room full of guys who were all to tightly on the same wavelength!

That or we all need to learn to type faster.

Looking at your robot, getting an elastic extension does look like a pretty hairy engineering problem. It could be done... but I'd hate to tac anything onto such a simple mechanism.

Re: Two pressures?
 

Yeah you can switch ken's model to extend with no air and then retract.
It's hard to explain well though.

Yeah tough, how does your mechanism set when it is extended or is the 24"cyclinder the bulk of the extension.

Re: Two pressures?
 

The bottom piston retracts to lift the bulk of the arm vertical. Then the 24'' piston extends to hook on. Then retracts to lift off the ground, currently this takes about 1 - 1.5 min with one accumulator.

Re: Two pressures?
 

If you can find a place that the latex tubing will pull enough that it will extend the cyclinder when it is pointing down and using the non-pneumatic air extension you can make Ken's spring way work. If not, route all exhaust from you cyclinder to a single solenoid with a stop on one of the output and block so you can control the stroke length of the cyclinder. You look like you could have the cyclinder partially extended to begin with and a least cut down on the wait for it to lift. Or you could lengthen your arm and purchase a shorter cyclinder. A 16" would do the job or even a 12" or 8" and would reduce the air needed. You lose height gained but an inch or 2 feet both get you 50 points. The one just works faster. I would add the second accumulator and make sure to reduce all tubing lengths. PM me and I'll give you more info about the single solenoid.

Re: Two pressures?
 

how about another idea. i can't see exactly how well this'll fit, but how about starting with your cylinder half extended. (use the double w/t single solenoid) from the angle of your photo, it seems like you may be able to do this. maybe.