Video Presentation

Specifications

This engine uses a 3-cylinder configuration with a 3x 120° crankshaft, enabling auto starting. Each cylinder acts on a switch which operate the next cylinder, removing the need of a flywheel (adding one reduce the leaps). It is built with a Scotch Yoke mechanism instead of a classic connecting rod/crank system and direct switch actuation to keep the size small (only 9.6cm in height). It doesn’t require to use any modified parts and runs with only one pump (slowly/jerky) or more faster/smoother with 4 LEGO pumps or other constant source of air.

In 2023, 14 years after the first prototype, I reworked completely the PDF Instructions, as well as updating the design to fit the new LEGO parts (especially the new beam 1×1 which helps a lot for the friction), which results in a better and smoother functioning and easy to follow instructions with clear layout for the hoses. I make a proper video, at this occasion.

How to build ?

Using Genuine LEGO Parts : You can purchase the PDF instructions on this shop and build with your own parts. The instructions contain the partlist at the end, but you can check on Rebrickable or in the preview below.

Please note that you need to have you own source or air (2-3 bars). You can use :

• 4x pump LEGO like this one
• Use a LEGO compressor according to the specs
• Use a electrical compressor like automotive compressor, industrial or electrical pump with ball needle.
• Use a hand pump with ball needle.

If you need to find hose 2/4mm, you can use blokbricks alternative hose.

Using non-Genuine LEGO Parts : This model is available on LesDiy Store in a complete package, including parts (alternative bricks from China) and PDF Instructions.

About this product

Instructions preview