Steam/air engine

I finally built something like a steam engine. This one runs on compressed air, but it’s the same idea. It uses a single cylinder, a flywheel, and a valve arrangement that looks like a cylinder.

The blue parts are all 3D printed, including the flywheel, the crank, and the collars/caps on the brass tubing (which serves as the cylinders for the piston and valve).

The valve works by moving 90 degrees out of phase with the piston and alternately trapping the supplied compressed air and admitting it to the cylinder. When the air is admitted the piston pushes on the crank, and when the air is trapped, the piston pushes the spent (exhaust) air out of the cylinder, back through the airway, and out through the bottom of the valve’s brass tube.

The valve is like a two-headed piston with an air chamber between the heads.

Below is a picture of the air supply system I rigged up. It allows the user to pump air into a soda bottle and then open the blue butterfly valve to allow the air into the engine. This is all just PVC, plastic tubing, and a brass airtank fill valve.

Finally, here’s a video of the engine in action. Future improvements include a more compact air system and actual piston rings that should help the piston and valve seal better inside the brass tubes.