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Unread 26-02-2011, 20:48
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Re: Solution: Variable position of cylinder in compliance with <R74>

Quote:
Originally Posted by GearsOfFury View Post
May I pose a practical question? Why do we think the GDC has this rule in place? Why not allow the use of additional pressure relief valves in line with the cylinder rod/head supply lines, mounted on your bot right next to the "main" relief valve? You could use quick-release toggle valves (e.g. http://www.mcmaster.com/#pneumatic-t...valves/=b7a2dk) to make it super-easy to relieve pressure in an emergency... One could even devise some kind of mechanical toggle that connects to the valves and flips all the connected reliefs at once.

So, is it a safety / emergency thing for use at the end of the match or in an emergency situation, or does the ability to trap air at mid-stroke during normal use pose some other safety concern?? I can't imagine the latter, or there wouldn't be much market for closed-center solenoids...!
Based on what I have read, they want all pressure to be released with a single action, the opening of the plug valve. I don't think the relief valve is involved in that much. The desire to release all the air with this single action stems from concern about people working around potential energy, in this case in the form of air pressure differential.

A secondary concern might be teams using isolating air from the rest of the system and compressing it to dangerous levels (in excess of 120 (or even 240) psi, if one designs the system "properly") and releasing the potential energy in a highly energetic manner that could be destructive and dangerous, even if the system survives long enough for the release to occur on command, in the desired manner. Additionally, it could be possible to design similar, though not quite as extreme, systems accidentally, even if the team tries to stay within the rules. In most applications, the system would be designed with this in mind thus making the use of center blocking solenoids practical.

Quote:
Originally Posted by Roboman01 View Post
That was the point. I was trying to describe a simpler system of controlling the cylinder.
I understand, and always have understood, that you were describing a different system. I just didn't want people to perceive either system as being more complex (or confusing) than it really was by trying to match the system I proposed to the system you provided a diagram of, since that is impossible due to the fact the systems are far from similar.

Also, 'simpler' is a matter of opinion, I consider mine to be simpler due to the fact that it doesn't require very much attention in the code, all you need to do is set the regulator and let it fine equilibrium with the spring on its own. Also, it isn't very complex physically either. I will draw a diagram and post it for clarity.
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