Build this air driven motor with my son to demonstrate how steam engines work. I was explaining how the 90 degree phase offset between valve and piston determined the direction of rotation. He sat for a few seconds with a thoughtfull expression and then stated “oh so if I suck in stead of blowing it runs the other way?!” … I didn’t see that comming and yes it does 🙂
Air motor, a set on Flickr.