What is a pneumatic
A pneumatic cylinder is essentially an industrial air ram. A sealed
piston and rod contained within a tube, a pneumatic cylinder uses
compressed gas to move the rod back and forth. There are two main
types, single acting cylinders and double acting cylinders.
What is a double-acting
A double acting cylinder can be moved in both directions (that is, the
rod can both extend and retract depending on which side of the piston
pressure is applied). A double acting cylinder internally looks like:
As you can see, a double-acting cylinder has two air ports. Depending
which port is used, the piston will be pushed to one side or the other,
therefore extending/retracting the cylinder. To run a double acting
cylinder, you need a 4-way valve. If the
cylinder is to move in one direction, the air behind the piston must be
exhausted or else it will act as a buffer.
What is a single-acting
A single acting cylinder has only 1 port, and can therefore only be
controlled in 1 direction. That is, you can have single acting
cylinders that have the rod normally retracted and when pressure is
applied it will extend and vice versa. Most have an internal return
spring, so the rod will return to its original position when there is
no pressure applied. A single acting cylinder typically looks like:
To run a single-acting cylinder you need a 3-way valve.
Where can I buy one?
eBay has some good deals most of the
time, and Surplus Center is
always good. Shipping is decent at Surplus Center, and their usually
selection of cylinders and valves makes it an indispensable source for
So what can you do with these things?
I use them for bolt action uses like on the CylBolt and ChewyCyl. I've
got some cannons in the works that will use them for barrel elevation
like on modern artillery. I'm eager to see other people begin using
Email me if you have any questions: John@NeoSpud.com
all images, text, and other content copyright 2006
John Shell, John@NeoSpud.com