With air pressure becoming a much more important resource to teams using pneumatic systems as they add more cylinders, I’ve decided to share my strategy to save as much pressure as possible.
Normally you fill up your reservoir(s) using the Schrader valve (bike pump fitting pictured above) with a combination of an air compressor or bike pump. The issue with this technique though is as you remove your compressor from the Schrader valve, you still push in the core, leaking extra pressure out of your reservoir(s).
Instead of using this technique for my own robot, I instead use this system pictured here.
How this system works is by first connecting your two reservoirs together to have equal pressure, and have a main line, with multiple T fittings connected on the main line to accommodate the amount of cylinders you have on you robot. In this example there is only one extra T fitting to accommodate 1 double acting cylinder but in theory you could connect an infinite number of T fittings for how ever many cylinder you use.
The next part of the system is the pneumatic switch on the end of the main line. By switching the direction of the switch, you allow the pressure to stay in the system without it venting out of the switch.
The last and most important part of the system is the fitting pictured above. For a pneumatic system to be legal, you have to use only the parts VEX sells or identical SMC parts. The fitting used here is not listed on VEX website or rule book and IS NOT LEGAL WHEN ON YOUR ROBOT. However, you can still use it to fill up your reservoirs. The fitting, which is a Schrader valve connected to a 4mm tube fitting, has a little bit of tubing connected to the end. You put that into the pneumatic switch, open the valve, and pressurize to 100 psi like normal. You then close the valve with the switch and only lose the air between the fitting and the compressor.
The two biggest advantages to this technique is the ability to place your reservoirs anywhere on your robot and losing the smallest amount of pressure possible. For example, right now on my robot, to aid balancing, I need all of my weight to be at the bottom of my drive base. With the technique I explained above, I am able to place my reservoirs in a really tight space all the way on the bottom like shown in the picture bellow.
Also, by filling my reservoirs with the normal valve, I would lose 10-15 psi. With the technique described above, I only drop to 1-3 psi. The link to where we got the Schrader valve to 4mm tube fitting is here. Let me know if you have any questions about the system and how to use it or if you have your own technique to hold more pressure.