Re: Solution: Variable position of cylinder in compliance with <R74>
 

I think that is a rather liberal way of reading the rule:
and
Good luck to you when you play. I just hope you have a "plan B" ready before you pack up for your regional, however.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

Actually, we didn't end up using this system at either the San Diego or the Los Angeles regional. We brought the system along with us, as a "Plan C," in case neither of our new gearboxes would lift the arm. Come to think of it, I should have had an inspector look at the system to determine its legality. I'll have to see about doing that at St. Louis.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

Yes, vacuum systems are exempt but you are talking about a hybrid pneumatic/vacuum system. Therefore, the system would almost certainly be considered pneumatic by an inspector.

Also, check valves are not legal this year.

JMHO,

Mike

Re: Solution: Variable position of cylinder in compliance with <R74>
 

Still, it's not generating any positive pressure, which is generally what "pressure" is considered. If I were to hook up gauges, such as the ones from the KOP, to each cylinder supply line, both would read 0 psi, since they only measures on a positive scale. The mere fact that a pneumatic system is a "hybrid" in a certain configuration does not necessarily mean that it is illegal. It would be considered a vacuum-generating device when pressure is released, and a pneumatic device when pressurized. In a week, after my spring break is over, I'll create a video to better demonstrate my point.

Also, since the "check valves" that I'm using are technically flow-control valves, they are legal, as I stated previously.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

I know what you have stated and I'm not going to argue with you as it seems that you have made up your mind.

However, for the sake of other readers, the GDC has stated that if a component contains a check valve, it is illegal.

I do not need to like their ruling and I will not defend it... However, if it walks like a duck and sounds like a duck...

JMHO,

Mike

Re: Solution: Variable position of cylinder in compliance with <R74>
 

The post you are linking to is from 2010. Also, flow control valves with built-in check valves are included in the KOP.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

My apologies on the 2010 link... I hate when I do that...

I don't know of any flow control valves in the KOP this year but I'll not press it...

Good Luck...

Re: Solution: Variable position of cylinder in compliance with <R74>
 

<R73> The pressure vent plug valve must be connected to the pneumatic circuit such that, when manually operated, it will vent to the atmosphere to relieve all stored pressure.

Doesn't indicate positive or negative pressure, simply all stored pressure.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

True, but negative pressure is a vacuum, and vacuums are not subject to the rules.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

If you use 5 port 4 way 3 position valve with presure center it will hold cylinder in any position and drain all air when you open your dump valve you may have to use regulator on non shaft side of cylinder to make up for area differance of shaft to avoid drift

Re: Solution: Variable position of cylinder in compliance with <R74>
 

If you use a valve in which the center position applies pressure to both ports, the cylinder rod will center itself. This may be desirable in certain cases, but it will not easily allow variable positioning.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

Originally Posted by cjwmam
If you use 5 port 4 way 3 position valve with presure center it will hold cylinder in any position and drain all air when you open your dump valve you may have to use regulator on non shaft side of cylinder to make up for area differance of shaft to avoid drift

If you use a valve in which the center position applies pressure to both ports, the cylinder rod will center itself. This may be desirable in certain cases, but it will not easily allow variable positioning.
__________________
BE A NERD!

We have a 30" cylinder on the center lift of our robot we can stop & start any where we want going up or down works great with the above valve when you open drain valve air exits both sides cylnder

Re: Solution: Variable position of cylinder in compliance with <R74>
 

Are you sure? That seems highly illogical, to me.

Re: Solution: Variable position of cylinder in compliance with <R74>
 

It would most certainly not center itself!

No matter where in the stroke it is, if the pressure on the 2 sides is equal, then the side with the larger surface area would be the side that "wins". The cylinder would extend. If a regulator were used on the other hand, then the valve would stop wherever it was.

Re: Solution: Variable position of cylinder in compliance with <R74>