He created an excellent centrifugal pump out of 100% LEGO. While mostly a curiosity, you can definitely get a sense of how the mechanics work. A Power Functions motor turns a 6×6 round plate ...

It has a sluice gate in the lower section to feed water to a turbine for power generation. The gate is moved via a rack and pinion. It’s driven by a LEGO motor on a long shaft to keep it a safe ...