What is the basis of the most innovative technological breakthrough today? What robots, 3D printers and new transportation equipment have in common is that they are all driven by planetary gearboxes. As a supplier of planetary gearboxes, of course, we know all the details, but when you first encountered this product?
What is a planetary gearbox?
A planetary gearbox is a reduction gearbox with the output shaft parallel to the input shaft. A planetary gearbox is used to transmit high torque in a compact form. (Referred to as torque density)
The acceleration hub of a bicycle is an excellent example of a planetary wheel mechanism: Have you ever thought about obtaining such a large amount of energy and ability in such a small hub? For a 3-speed hub, a one-stage planetary reduction system needs to be used, while for a 5-speed hub, a two-stage reduction system is needed. Every planetary deceleration system has a deceleration state, a direct coupling and an acceleration mode.
Explained in mathematical terms, the smallest reduction ratio is 3:1, and the largest is 10:1. When the speed ratio is less than 3, the sun gear will become larger compared to the planetary gear. If the speed ratio is greater than 10, the sun gear will become smaller and the torque will drop. The speed ratio is usually absolute, that is, an integer.
I don't know who invented the planetary gearbox, but it is generally described as being made by Da Vinci in 1490. And it has been used to this day.
Why is it named a planetary gearbox?
The reason why planetary gearboxes got this name is that different gears work together. In a planetary gearbox, we can find a sun gear, satellite gear and two or more planetary gears. Generally speaking, the sun gear is driven, and thus drives the planetary gears locked in the planetary carrier and forms the output shaft. The relationship with the outside world is that the satellite gear has a fixed position. This looks very similar to the solar system. So, this is the origin of its name.
In reality, we usually talk about the use of planetary gearboxes from the field of industrial automation. This is why we call the sun gear the input shaft, the planetary gear and the carrier the output shaft, and the satellite gear (or ring gear) the housing.