I just completed my second ever air engine: The Chuffer. With this project I decided that I’d go for complexity, rather than the simplistic approach I took when I built The Wobbler earlier this year.
The Chuffer is a twin-cylinder double acting engine – which means each of its two cylinders both push and pull the piston. This means it operates much more smoothly and can self-start as there’s always a piston on a power stroke, regardless of where the flywheel is.
Unlike its predecessor, the Chuffer has fixed cylinders and airflow is controlled by two spool valves, operated by eccentrics next to the flywheel via some pushrods and a hopelessly over-engineered lever mechanism.
And of course everything was made by yours truly, in the garage, from chunks of brass, steel and aluminium bar and flat stock I bought on eBay. Needless to say, I have learned a lot since I started the project this February!