A planetary gearbox is a gearbox with the input shaft and the result shaft aligned. A planetary gearbox is used to transfer the biggest torque in the many compact form (known as torque density).
The bicycle’s acceleration hub is an excellent exemplory case of a planet-wheel mechanism: Have you ever wondered ways to get so much power and capabilities in such a little hub? For a three-velocity hub, a one-stage planetary equipment system is used, for a five-speed hub a 2-stage. Each planet gear system has a reduction state, a primary 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, sunlight gear becomes too big against the planet gears. At a ratio higher than 10 the sun wheel becomes too small and the torque will drop. The ratios are often absolute i.electronic. an integer number.
Whoever invented the planetary gearbox is not known, but was functionally described simply by Leonardo da Vinci in 1490 and has been used for centuries.