A planetary gearbox is a gearbox with the insight shaft and the result shaft aligned. A planetary gearbox can be 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: Perhaps you have ever wondered how you can get so much power and features in such a little hub? For a three-swiftness hub, a one-stage planetary gear system can be used, for a five-speed hub a 2-stage. Each planet gear program includes 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 significantly less than 3, the sun gear becomes too big against the planet gears. At a ratio greater than 10 sunlight wheel becomes too little 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 simply by Leonardo da Vinci in 1490 and has been used for years and years.