Motorizied flow control

[ollien]

Originally Posted by mman1506

We had a team pass with something similar at Waterloo, the LRI and I couldn't find anything illegal about it. As long as the pneumatic fitting remain unmodified It should be fine. I would still consult the Q&A as the ruling of inspectors could vary and It could potentially save some time during inspection.

Dare I ask what this was for?

[mman1506]

Originally Posted by ollien

Dare I ask what this was for?

The team wanted to have a 3rd position for their air cylinder. I think the plan was to actuate the cylinder with the solenoid and use the servo to let out air until it was the right height. I don't think they ever got it functioning.

[jspatz1]

As already mentioned the problem with your system is not the flow controls, but the 3-position valve.The question of using a 3-position valve to achieve intermediate cylinder positions has come up many times. If the center valve position is both-ports-closed, this technique is illegal because it creates closed, pressurized lines that are not vented when the system is vented. If the center valve position is both-ports-exhausted, this should be legal, but would have no ability to hold its position on its own.

[FrankJ]

It is a little Rube Golbergish, but there is a way to make a closed center 3 position valve legal under 2016 rules. You use check valves to allow both sides of the cylinder to flow back the working pressure side of the system. They won't do anything when the system is pressurized, but they will vent the cylinder when the system is depressurized.

[FrankJ]

Attached is a sketch on how to use check valves to make using a closed center 3 position valve legal under FRC rules (at least for 2016)

[Levi Madden]

Originally Posted by FrankJ

Attached is a sketch on how to use check valves to make using a closed center 3 position valve legal under FRC rules (at least for 2016)

It is important to note that you connect the check valve to your working pressure, not your stored.

[nuclearnerd]

Originally Posted by FrankJ

Attached is a sketch on how to use check valves to make using a closed center 3 position valve legal under FRC rules (at least for 2016)

Oh very cool, thanks! With a setup like that you could create a pneumatic position control system (like http://www.bimba.com/Products-and-Ca...ntrol-System/). Add a pneumatic rod lock (http://www.bimba.com/Products-and-Ca...Line-Rod-Lock/) and you could move and hold actuators with very few mechanics.

The downside is the limited compressor size means you wouldn't be able to move a cylinder bigger than ~1" more than a few cycles a match.