Pneumatics Questions

VEX V5 Technical Support UNOFFICIAL Tech Support
1

So our team recently got a pneumatics kit and we are using the double acting pistons. We have a few lot of questions:

  1. There is air leaking out from the two uncovered input holes in the solenoid, and this causes air to be lost very quickly. Is this supposed to happen, and if it’s not, is there any way to fix this?? Do we just cover them with teflon tape?

  2. Currently, I have the solenoid programmed with 1 and 0. For the double acting pistons, I expected both retraction and protraction to be quick, but only protraction (is that even the right word) goes fast. The piston still moves both ways, its just that it shoots out but retracts slowly. Is this in the coding or the tubing? This isn’t a huge problem, but it would be nice to have it fixed.

  3. How many reservoirs would be recommended/psi we should pump to for each piston if we want at least 20-30 retractions/protractions?

  4. We are planning on doing the US Open in Iowa. Would flying on a plane with a reservoir be a smart idea? Or is ground shipping a better idea?

  5. I don’t see any way to mount the reservoirs onto the robot, is it legal to just tape them onto the robot??

  6. Is there a limit to the amount of reservoirs we can have on a robot?

  7. When you connect reservoirs together and pump one of them, do they both pump up? Or do we have to pump both reservoirs separately?

  8. Are there any tips and tricks that was not asked that we should know of?

I know that’s a lot of questions, but we would really appreciate it if they could be answered. Thanks!

2
  1. the valves are removeable. Take them off and it’s depressurized. Do this after u drain all the air
  2. 2
  3. only if they are joined before a solenoid or otherwise isolated system. Essentially you are filling up the, and the closed area before the solenoid.
3
  1. Flying should be fine; just remember to release all the air
  2. Zip ties
  3. 2 reservoirs
  4. They should both pump up at the same time
  5. Try to keep the solenoid as close to the piston as possible
4

The pneumatics kits are provided with two different cylinder fittings: one is a simple straight connector, and the other is an exhaust flow control valve. The exhaust flow control valve allow you to adjust the speed of the cylinder by restricting the exhaust as the piston moves inside the cylinder housing (there is no restriction on the input, just the exhaust). If you want to control speed of the cylinder in both directions, then use two exhaust flow control valves. If you don’t want any speed control, then use straight connectors on both ends of the cylinder.

Best tip: get a small plastic squirt bottle, and fill it with water and a bit of dishwashing soap. Use it to detect leaks at the fittings.
Second best tip: Use a small hex key wrench inside the various fitting to tighten them.

5

I’ll answer what I know, as I haven’t dealt with pneumatics before.

  1. Make sure all your connections are secure. If it persists, get new parts.

  2. Don’t know.

  3. My friends usually pumped their reservoir to 100 PSi

  4. As long as you depressurize it and keep the valves open, you shouldn’t have a problem.

  5. Use 90 degree angle channels and ziptie the reservoirs to that. This setup is best to place lower on the robot, because it has an added bonus of acting as an as an anti tip counterweight.

  6. 2 Reservoirs.

  7. They both get filled, assuming you have it connected properly.

  8. For tips, you should ask teams that use pneumatics in their robots.

6

  1. defiantly use Teflon tape, unscrew all threaded fittings, wrap a layer of the tape around the thread, and screw it back in, if possible, use pliers to tighten

  2. there are two types of fittings that screw into pistons, a small brass one, and a larger white plastic one. The white plastic one restricts air flow. Don’t use the white ones, they sometimes keep pistons from retracting all the way. Buy more pneumatic kits, or buy the brass fittings directly to get more of them.

  3. two reservoirs, and 100 psi

  4. it should be fine to fly on a plane with it

  5. use the large zip ties

  6. yes, two

  7. they both pump up

  8. use as little tubing as possible between the solinoid and piston.

Please mark this thread as solved

7

These little M3 fittings seal with a small gasket. Use tape if it makes you feel better, but it is the gasket that actually seals the fitting. Don’t get any tape where it will interfere. All the solenoid and cylinder fittings have a hex-key recess inside the fitting. Get a set of metric hex key wrenches. The manufacturer’s specification is to tighten them finger tight, then turn 1/3 additional turn with a hex-key wrench for the gasket to properly seal.