The engine fully performs its educational and cognitive function. Workmanship at a height, the appearance is very, as for me, pleasant. Axes of rotation fasten through miniature bearings. The rotation of all engine nodes is smooth and quiet. The assembly is excellent, everything is clean, no fingerprints, drips of oil, dirt, etc. Just perfect. Basic materials - steel, duralumin flywheels, counterweights
This is a vacuum engine. When properly adjusted it works well On mine the round rod at the top, the one that moves the hole covering leaf type valve, needed to be adjusted. This can be done by holding the levers at the side with thumb and forefinger of one hand while moving the round rod slightly up or down. When moving the flywheel counterclockwise, a cliciking soind should be heard. One needs to play with it by trial and error until the motor runs well. The hole in the front needs to be completely covered when in the lower position.