Quote:
Originally Posted by Kevin Sevcik
It will work. They will not extend at the same time, most likely. Water, air, and electricity all take the path of least resistance, so the piston with the least load/friction will extend faster and/or before the second piston. This would be a problem even with seperate solenoids, though not quite as big.
The only sure fire solution is basically to seperate the two solenoids with check vales and things so they're operating from different pressure sources.
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Actually, you'd STILL get the above problem with that method. Think about it. Nothing has changed WRT the loads themselves.
Off the top of the head, I can only think of two ways to insure they move together
perfectly in sync:
A) Mechanically tie the pistons together via some mechanism. (But heck, if you did that, why bother with two cylinders in the first place???)
B) Use closed loop controls, position monitoring, and more complex valves than are supplied, to monitor and "throttle back" the faster cylinder based on its motion. (This is MUCH more complicated, and rarely if
ever worth the effort!)
Honestly, if you REALLY need two things to go EXACTLY together, figure out a way to mechanically couple them, and drive them both with one cylinder simultaneously.
One example might be to use a differential bell crank. With servos, you simply use opposing ends of the "X" horn on the top of the servo, and run links out both ways.
With a cylinder, you "float" the "X" - two opposing ends go to your two devices, and a third end runs over to your cylinder. When the cylinder pushes or pulls on the crank, the two devices switch together.
(Warning - With ANY bell crank system, be sure to use a spring loaded "servo saver" ends to prevent over-run freeze-up. Otherwise, the load that switches first and hits ITS stop will freeze the crank. This could prevent the other load from fully switching!)
Does this make sense?
- Keith