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Unread 10-09-2004, 01:37
ngreen ngreen is offline
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AKA: Nelson Green
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Re: pic: 6 speed?? Great in theory - lets see how it works!

Depending on how relaxed the pneumatic rules are this year there are three position solenoids that have a stopped position. This would be your best option along with magnectic reed switches to tell your stroke where to stop. A little programming and you have a decent solution.

In the past we have not had the three position solenoid and had to refer to using multiple solenoids(best combo is a single and double) to create a hard stop, aka plugging the exhaust tube when we want it to stop and exhausting when we want it to move. This could be used with the magnectic reed switches to create a solution that works. As with most pneumatic one of the biggest keys to this is shortening all your pneumatic tubing so that there is at least amount of slop as possible.

My use of it was not a precise as shifting gears but I imagine if you implement it right with the reed switches and a little programming it could work fairly reliably.

Just a note: Magnectic reed switchs are generally used to tell if a cyclinder is fully extended or retracted to allow automation of pneumatically controlled process. I have not personally tested the above mentioned using magnectic reed switch at mid strokes but it seems that with programming it would work. Also the above mentioned way of stopping midstroke(the second one) is achieved by equally the force on the two sides of the cyclinder. Force in this case is a pressure per area. On the stroke side of the cyclinder the area is reduced by the area of the stroke, the other side remaining the same, this will cause the pressure stroke side to increase. This has caused discussions whether it would violate the 60psi rule. Take this thought in when designing such a pneumatic system. Safety is important.
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