The main transmission structure is the planetary gears, sun gear, and ring gear. The sun gear driven by an external power is located in the center of the gear set. As the sun gear rotates around the driving shaft, the three planetary gears revolve around the sun gear. The planetary gears are distributed equally on a so-called planet carrier. The ring gear is in close contact with the internal gearbox housing. 

These three gears are directly supported by the output shaft, ring gear, and sun gear, which float in it. When the sun gear is driven by the input power, the planetary gears start to rotate around the center as well as the orbit of the ring gear.

If you want to achieve high torque while reducing the processing speed, a planetary gearbox might be an ideal choice. In real life, you’ll find them not only small machines like electric screwdrivers but large units like bulldozers. They are better than both helical and spur gears when it comes to efficiency, durability, and horsepower. Now, let us look at all of the advantages of it:

Several planets or airplanes share the load instead of one gear. The more of these planets are incorporated into a gearbox, the better the shared load efficiency. This leads to higher power density.

A planetary gear reducer is highly efficient due to its unique design. Although many speed gear reducer manufacturers do not disclose efficiencies in their catalog directly, there is a simple calculation you can use to obtain the value:
Input Power/Output Power=Efficiency

These devices have a very compact design compared to other speed reducers and as a result, usually weigh less than other types. With this device, you can achieve as much as a 50% size reduction while maintaining the same torque output.

Thanks to the torsion rigidity and better rolling properties of planetary gear reducers, they usually last longer and are not as prone to malfunctions. Bearings help reduce the damage caused by rubbing the shaft directly on the box. Therefore, higher gear efficiency and smoother operation are achieved.

Higher radial and axial load speeds provide reliability and sturdiness, which results in a significantly lower risk of gear misalignment. Besides, planetary gear reducers ensure a constant and uniform transmission and greatly reduced vibration under different loads. All these result in higher precision and therefore increased repeatability.

As more teeth come into contact, the mechanism can transmit and withstand greater torque and transfers the power more evenly.

The mechanism is installed in a cylindrical gearbox and can be installed in almost any space. On top of that, planetary stages can be stacked which allows for high customizability.