Pneumatics not strong

[Alpha_Dream_3]

Hello. I have question for using pneumatics. My team and I installed the vex pneumatics. We installed 1 piston only as of now. We are using double acting cylinders. It does not seem to be strong at all. It extends but not at 12 lbs of force as it says it should. I don’t know if its an air leak. If anyone knows, could you possibly tell me?

[DRow]

I’ve moved this thread to the general tech support channel.

[xRiloKOTBx]

This is kind of hard to respond to since their could so many things that are causing your problem. I will start of by saying that I personally never use pneumatics for lifting and/or suspending things in the air. Pneumatics are not strong enough. However, pneumatics are used to offer actuations under light amounts of stress. For example, in last years game it was fairly common to see a pneumatic claw on robots. These systems worked by offering a quicker way to group up the elements, but could not hold onto the elements for an extended period of time and would require some sort of forklift at the bottom of the claw. What I’m getting at here is that the pneumatic systems for vex are really meant for those really quick actuations under little stress. Now I don’t know what you are planning to use your pneumatics for but I understand that you are having an issue with the piston. This could be due to a leak, although you would probably hear it. Or it could be a more simple matter of just filling your reservoir. This is what I’m thinking is happening, the pneumatic pistons do offer around 12 pounds of force fully pumped and with nothing attached to them. When there is opposition to where the piston wants to move it won’t go at full force. If you are trying to lift something of reasonable weight such as a mobile goal I would tell you to look at using more than one piston. It all depends on what your going to do. Hopefully this helped with your issue and remember if pneumatics don’t work, you can almost always builtd something with motors.

[Tim_Jang]

My team also had a lot of issues with pneumatics last season. I don’t know if your team is having the same problem that we had last year, but this is how we troubleshooted until we assured that our pneumatic system was fully functioning:

1. pump the tank to 100, but don’t take off the air pump off of it, and see if the air pressure decreases using the gauge on the air pump; if it does, then there is a leak in your system.
2. wrap a sufficient amount of teflon (plumbers) tape on all fittings.
3. once you tighten all the joints, use pliers to tighten them again - but not too tight.
4. before you insert the tubing into the fittings, make sure that the ends of them are not crooked - make the cut as straight, and clean as possible.
5. Reduce the length of the tubing from the solenoid to the piston as much as possible.
6. repeat step 1 and if all goes right, the air pressure should remain relatively steady.

I hope this helps!

[kmmohn]

You might find the attached document helpful.
pneumatics information.pdf (313 KB)

[bryanr]

My guess is the only thing you are doing wrong is using the 90 degree white fittings on the pistons. Those restrict air flow unless you loosen them, but when you loosen them, they leak air. The solution is just to use the gold fittings that can also screw into the pistons.

[reflxshn]

We currently have a prototype with 2 “pistons” holding the MB with a small 4 bar lift. There are two positions on the lift low and high. The low position gets it just over 10pt bar. The high clears the large pole. It seems to have just enough pressure for 2 high lifts and 6 low (min needed for skills) but not much more. Were building a second MB lift now with motors and my guess is that we will ultimately go that way. Also… be sure you are not using single activation “pistons”. The internal spring reduces the output of the expansion significantly. I’ve also seen damaged or “sticky” pistons cause problems. Good luck.

[Alpha_Dream_3]

@xRiloKOTBx

What I’m getting at here is that the pneumatic systems for vex are really meant for those really quick actuations under little stress. Now I don’t know what you are planning to use your pneumatics for but I understand that you are having an issue with the piston. This could be due to a leak, although you would probably hear it. Or it could be a more simple matter of just filling your reservoir. This is what I’m thinking is happening, the pneumatic pistons do offer around 12 pounds of force fully pumped and with nothing attached to them. When there is opposition to where the piston wants to move it won’t go at full force. If you are trying to lift something of reasonable weight such as a mobile goal I would tell you to look at using more than one piston. It all depends on what your going to do. Hopefully this helped with your issue and remember if pneumatics don’t work, you can almost always builtd something with motors.

Well, I am using it for my claw which is supposed to pick up the cone, I tried using it without picking up the cone and it didn’t work. I also had my tank up to full,

[Alpha_Dream_3]

@Tim Jang

1. pump the tank to 100, but don’t take off the air pump off of it, and see if the air pressure decreases using the gauge on the air pump; if it does, then there is a leak in your system.
2. wrap a sufficient amount of teflon (plumbers) tape on all fittings.
3. once you tighten all the joints, use pliers to tighten them again - but not too tight.
4. before you insert the tubing into the fittings, make sure that the ends of them are not crooked - make the cut as straight, and clean as possible.
5. Reduce the length of the tubing from the solenoid to the piston as much as possible.
6. repeat step 1 and if all goes right, the air pressure should remain relatively steady.

I hope this helps!

I will try this and see if it works! Thank you!

[Alpha_Dream_3]

@kmmohn

You might find the attached document helpful.

Yes, I read through it and I will go check on a few things. Thank you!