A planetary gearbox is a gearbox with the input shaft and the output shaft aligned. A planetary gearbox is utilized to transfer the largest torque in the most compact form (known as torque density).
The bicycle’s acceleration hub is a good example of a planet-wheel mechanism: Have you 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 equipment system is used, for a five-quickness hub a 2-stage. Each planet gear system includes a reduction state, a direct coupling and an acceleration setting.
In mathematical terms, the smallest reduction ratio is 3: 1, the largest is 10: 1. At a ratio of less than 3, the sun gear becomes too big against the earth gears. At a ratio greater than 10 sunlight wheel becomes too little 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 by Leonardo da Vinci in 1490 and has been used for years and years.