This is our pretty much our first time working with pneumatics so I’m not sure if this is normal. The double-acting pistons extend very quickly but then retract super slowly and difficultly. (If we switch the connectors on the pistons then the fast/slow directions reverse). Is this the way it’s supposed to be and is there any way to make them go fast in both directions?
there are two kinds of connectors that are used un double acting cinders.
the one that has the 90degre bend in it has a limiter on the flow that it let’s out.
Tis can be adjusted with a standard screwdriver by turning the adjuster that is on the inside of the pocket thing (metal part).
im going to assume 2 thing one is that you have the piston not attached to your robot besides the tube going to the solenoid
second im going to assume that you have the 90 degree attachment to the piston with the straight attachment. what you would need to do is get a small set of pliers or a small flat head screwdriver and turn the flow control to allow more air to flow through.
Pictures always help. 
It sounds like it is a solenoid issue. Have you tried a different solenoid?
That fixed it. Thanks guys!
Is there any advantage to keeping it turned down? Or should we just leave it all the way open?
They have that option so that you can choose to make the piston retract slowly or quickly, depending on your needs. But I just have it all the way open yeah, it makes them work the same as the brass colored connecters.
This changes everything…