A planetary gearbox is a gearbox with the insight shaft and the result shaft aligned. A planetary gearbox can be used to transfer the largest torque in the many compact form (referred to as torque density).
The bicycle’s acceleration hub is a superb example of a planet-wheel mechanism: Have you ever wondered ways to get so much power and features in such a little hub? For a three-acceleration hub, a one-stage planetary gear system can be used, for a five-swiftness hub a 2-stage. Each planet gear system has a reduction state, a primary coupling and an acceleration setting.
In mathematical terms, the tiniest reduction ratio is 3: 1, the biggest is 10: 1. At a ratio of less than 3, sunlight gear becomes too big against the planet gears. At a ratio higher than 10 sunlight wheel becomes too small and the torque will drop. The ratios are usually absolute i.e. 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 centuries.