Retracting a cylinder?

[greatman05]

Hello. I was thinking about this for a while, and I'm still kind of stuck as to how it works. I've heard that it's possible to retract a cylinder without using some kind of motor "rewind" mechanism; is this true? Also, how does the programming for this work? This might not be the right forum for that last question, but does this mean that the button I program it to will have to be held down for the cylinder to fully extend, and then once it's let go, the cylinder automatically retracts?

[EricH]

It is. You fire the other side of the solenoid valve, which sends air into the other end of the connected cylinder. Programming depends on whether a single or double solenoid is used.

[greatman05]

We planned on using double solenoids for the two cylinders we're going to use. Does the last question I asked earlier work for those, or is there something special I need to do?

[Daniel_LaFleur]

Originally Posted by greatman05

We planned on using double solenoids for the two cylinders we're going to use. Does the last question I asked earlier work for those, or is there something special I need to do?

The Festo solenoid that you recieved in the KOP is not a 'double solenoid'. It is a 4 way solenoid designed to control both the extension and retraction of a cylinder. While it can be used to control the extension of 2 cylinders (firing opposite) it won't be able to retract them.

[greatman05]

We're using the SMC solenoids.

[Racer26]

Originally Posted by greatman05

We planned on using double solenoids for the two cylinders we're going to use. Does the last question I asked earlier work for those, or is there something special I need to do?

Look at the attached picture:

Pressure goes in at P.

If you energize one side of the double solenoid, pressure flows from P to A, through the cylinder actuating the cylinder in one direction, then from B to EB.

If you energize the other side of the double solenoid, pressure flows from P to B, actuating the cylinder in the opposite direction, and then from A to EA.