Home > Lego Steam Engines > Single acting one cylinder

Single acting 2x2 one cylinder lego steam engine

Building a working model of a steam engine out of Lego wasn't easy. I built my first engine when I was 15, (that's been quite a few years ago) and still learning this! Building a solid structure, keeping friction down, and keeping things balanced are important in the design. I found that the engine's rpm improves with a design that allows air to escape during the exhaust stroke.

View from the air input side

Here's a shot of the air inlet. This inlet is configured so that the hole in the side of the cylinder lines up with it at just the right moments to provide the power stroke.

Flywheel side view

Veiwing from the flywheel side of the engine. I didn't have the standard "+" shaped hub for the tire, so I improvised using a freewheeling hub and a 2x2 round from a space lego set which happened to have the "+" hole through the center.

Another air input side view

Here are two side views. Notice how the base of the engine is rather massive. This accomplishes two purposes. It keeps the engine from tipping forward and also dampens vibrations for smoother running. (Believe me, it makes a difference.)

Another thing to note is the position the crank wheel and cylinder are in. This is the starting position. A good hard blast of air into the inlet will set the engine in motion without having to spin the flywheel.

Top view

Finally, top views. I don't know if these photos are enough to go by to build your own engine just like this, but it gives you a sure start.

Front view