A planetary gearbox is a gearbox with the insight shaft and the 
result shaft aligned. A planetary gearbox is used to transfer the biggest torque in the the majority of compact form (known as torque density).
The bicycle’s acceleration hub is a good exemplory case of a planet-wheel mechanism: Have you ever wondered how you can get so much power and capabilities in such a small hub? For a three-rate hub, a one-stage planetary equipment system is used, for a five-rate hub a 2-stage. Each planet gear system has a reduction state, a direct coupling and an acceleration mode.
In mathematical terms, the tiniest reduction ratio is 3: 1, the largest is 10: 1. At a ratio of less than 3, the sun gear becomes too large against the earth gears. At a ratio greater than 10 the sun wheel becomes too little and the torque will drop. The ratios are usually absolute i.electronic. an integer number.
Whoever invented the planetary gearbox is not known, but was functionally described by Leonardo da Vinci in 1490 and has been used for years and years.
