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.

Design & Working Principle of Planetary Gear Reducer, Wittenstein Group

Advantages

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:
 

High Power Density

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.
 

High Efficiency

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
 

Compact Size and Low Weight

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.
 

Excellent Durability and Longer Life

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.
 

Increased Repeatability

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.
 

Increased Torque Transmission

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

Maximum Versatility

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.
 

Applications

Planetary gearboxes have the aforementioned benefits of compact size, lightweight design, strong load capacity, high reliability, low noise, large output torque, large speed ratio range, high efficiency, and incredible versatility. Thanks to these advantages, planetary gear reducers are suitable for lifting and transportation, construction machinery, metallurgy, mining petrochemicals, construction equipment, light industry and textile industry, medical equipment, instrumentation, automobiles, ships, weapons, aerospace, and many other industrial sectors.

Some models have a square flange design, with simple installation in mind, which makes them suitable for AC/DC servo motors, stepper motors, and hydraulic motors, etc.