Those 2 match best the design i had in mind:
http://www.animatedsoftware.com/pumpglos/propelpu.htm
http://www.animatedsoftware.com/pumpglos/progrssv.htm
But in the end, the internal working aren't that important.
I just need a pump that had a cilindrical form so i don't loose too much place, since place is very limited in a shuttle.