Planetary Gear Assembly

myminifactory

The planetary gear assembly or epicyclic gear train is a system that revolves around one or more outer gears, known as planet gears, which orbit a central, sun gear. The Greeks were the first to employ this device, naming it after its original application in modeling planetary movements in the heavens. By inventing epicycles, circles traveling on circular orbits at around 500 BCE, the Greeks were able to approximate the moon's elliptical path through the heavens with remarkable accuracy.