# Pneumatics

I have 2 questions

1. how do i fill up a resivour with a bike pump without it leaking out at the end?

2.i have a pressure gauge that shows lbs can i check if im at 100 psi with that?

kk im sry i tottally forgot

1. On the Tire Pump Fitting, there is a nut that is screwed down all the way on the place where you put the pump nozzle. Unscrew the nut and take it off.

2. PSI = Pounds per Square Inch. If something pneumatic measures in “lbs,” it means PSI.

1.it fills up fine it just at the end when i pull the lever down to unhook the pump it comes out

1. how do i check that with this pressure gauge
1. Yes, some comes out. However, it is a trivial amount and doesn’t really matter (if you unplug it fast enough).

2. Oh. That won’t work with the nozzle as far as I know. Most bike pumps have a meter built in…

kk thanks so much for your help and my bike pump has a gauge but i just wanted to be sure and how do the judges test the air level at worlds

Actually, they don’t test it at Worlds. (At least, I’ve never seen them do so.)

However, if a question ever arises about the amount of air you’ve pumped into the system, I would think that they would just have you release all the air, and pump it back with them watching.

I have another question how much weight can i put on the pneumatics double acting cylinder in its outward position and how much can it pull
(weight in sacks would be helpful)

This will depend on the weight of your lift assembly and where the cylinder is mounted in reference to it’s distance from the mounting point of the arm. If you think of your lift as a simple lever such as a teeter totter you can see what I am trying to get at. If you provide an estimated weight of the assembly, the length of the arm you are lifting, and then the size and mounting location of the cylinder you will be more likely to get an accurate answer.

it is mounted on our intake so it is flat when we are collecting sacks and it raises to score them

Are you using one cylinder or two? Are they mounted directly to the intake cylinder and not with any type of scissor lift assembly or other type of device that will effect leverage? Also what is the weight of your intake?

Here is the information from the instructions for your cylinder;

The equation for calculating the Output Force for a specific pressure is given as:
(Cross Sectional Area of Cylinder) x (Internal Air Pressure) = Force
The cylinders bore of the VEX Pneumatic Cylinders is .39 in (10 mm).

From this we can calculate the cross sectional area of the cylinder by using the equation for the area of a circle: (Diameter / 2)² x Pi = Area

As we are given the cylinder bore (inside diameter) and we know that Pi ≈ 3.14, we can calculate the area to be:
(.39 in / 2)² x 3.14 = .12 in²

We can now plug this number into our original equation and calculate the cylinder output force:
.12 in² x 100 psi = 12 Pounds of Force (at 100 psi)

You should be able to initially lift 12 bags less the weight of your intake, but this will diminish over the rated 45 cycles of the cylinder before the pressure reaches 25psi.

it is 2 cylinders with a direct connect so it should lift 24 sacks right and the intake weighs nothing

and is it fine if i have that kind of weight on the cylinder in its open position

I would be careful of any sudden stoppage, with the cylinder fully extended, you need to worry about bending the shaft on the cylinder with that kind of weight. It’s kind of like putting a bowling ball on a broom stick and stopping suddenly. If my memory and my math serve me correctly 10kg 8.25" from the base of the cylinder works out to about 40kg. (88lbs) of force not considering velocity which is a consideration.

The last pneumatic cylinder I used was a 4" bore over 20 years ago, so maybe somebody who has experience with these cylinders can share some experience with you. I do think it will work for you since it would take more than 88lbs of force to bend the shaft, you just need to exercise a bit of caution.

I also need help on programming the pneumatics itself. I have very little experience with pneumatics

Is the air from the pneumatics controller supposed to come out fairly quickly

Almost instantly.

is it supposed to happen

Do you use Easyc or RobotC.