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Unread 23-03-2004, 15:39
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Mark Ivey
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Re: Mulit-postioning with pnuematics this year?

Unfortunately the multi-positioning solenoids are illegal accoring to the flow chart. But to ngreen's posts on the pressures equalizing, or one pressure overcomming the other and the piston continuing to move, depending on how you do it, I guess, this doesn't happen. The way you described is that you are connecting the exhaust of one double solenoid to the ouputs of another, and locking the exaust depending on what point you want it. The issue causing the creep in the piston is that you are not giving a "total cutoff", nor are you regulating pressure at all positions. The creep comming from not being able to cut everything off is because you are not switching the exaust to something that is pysically cut off, the pressure in port on a solenoid can sometimes allow exaust, that's why you may have the creep. The way to stop DEAD is by completly blocking all air through the exaust of one side of a solenoid. But even then you will have some drag, like a car slamming on breaks. The key is to eliminate as much of this drag as possible. That's what Leo and I did last night. We decided we would take the task on one more time. We used all legal parts, and we have reduced the drag to less than a half inch. But there is a down to every good thing, while reducing the drag, we have to slow the throw rate of the piston, so it moves somewhat slow. It's a way of running this that we had not expected, and in doing so we found two new ways from using 3 solenoids. Thus we have cut weight in the overall function. The first method requirments 2 double action solenoids, or 1 double action and 1 single and a piloted check valve, while the second requires 2 double solenoids and 2 check valves. I won't give a long drawn out explination, but I will include diagrams, showing the two ways.
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