Pneumatic engines aren’t something we use every day, but they’re compelling things to see working in practice. [Nico71] built an eye-catching example out of LEGO Technic, and it’s remarkably fully-featured.
The build relies on a single pneumatic cylinder driving a flywheel. Flow to the cylinder is determined by camshaft-controlled valves. The valves themselves are custom-built, composed of hose loops that are kinked to shut off flow. In addition to the basic operating components, the engine also features a throttle valve which uses the same kinked-hose principle. The main control valves are installed in a housing that can be rotated relative to the engine’s frame to vary the timing of the valves relative to the flywheel’s rotation. A gear system allows fine adjustment of the timing. The throttle and timing controls are accessible on a tidy control panel complete with a idle-adjust mechanism.
Those wishing to build one themselves can rejoice, for [Nico71] provides instructions for a small fee. We’ve seen other air engines before, too, often of the 3D-printed variety.
Naturally, though, the video saves the best for last. The big transparent sphere is installed in a rig that surrounds it completely. The sphere itself is spun up thanks to wheels installed on two different axes. This allows the sphere to be spun in various directions under command from a PlayStation controller, creating more complicated vortexes and flow patterns. A set of swiveling casters are provided to hold the sphere in place as it rotates in various directions, and are damped with springs and rubber bands to stop the rig shaking itself apart.
