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 ways to get so much power and features in such a little hub? For a three-speed hub, a one-stage planetary equipment system can be used, for a five-rate hub a 2-stage. Each planet gear system includes 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 significantly less than 3, the sun gear becomes too large against the planet gears. At a ratio higher than 10 sunlight 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 simply by Leonardo da Vinci in 1490 and has been used for centuries.