On Wed, 27 Aug 2008 21:14:45 -0500, Lloyd E. Sponenburgh wrote:
....
I emailed one to you, and put it in the dropbox, as well.

"Sock Actuator.jpg"

Ie, http://metalworking.com/dropbox/Sock_actuator.jpg

As you've drawn it, it looks like pulling a vacuum would tend
to collapse the membrane. Conversely, it looks like a proper
setup for pneumatic operation.

If the push rod and vacuum inlet had their positions swapped,
pulling a vacuum would pull the membrane out against the cylinder,
improving the seal. Conversely, pneumatic operation would tend
to collapse the membrane.

In short, from your earlier description I had envisioned the
membrane being on the other side of the vacuum, ie, with the
vacuum inlet on the left and push rod entering on the right.
So, have I got things backwards, or maybe the direction doesn't
matter?

-jiw