Nico71 - Lego Switchless Pneumatic engine mk2. With stacked 4 valves instead of side by side, one cylinder and two speeds gearbox. Expected to me mounted soon in a two wheels creation
Pneumatic Mine – Nico71's Technic Creations
Instructions Pro - 1 Cylindre Switchless Lego Pneumatic Engine 2500 RP – Green Gecko Workshop