Planetary Gear Reducer

A planetary gear reducer is a special transmission mechanism that aims to transmit a maximum torque in the most compact form. Simply speaking, it is a gearbox with the input shaft and output shaft aligned within it. As the name suggests, the planetary gear reducer decreases the number of motor revolutions and ensures high torque through the speed sensor. But how exactly do planetary gear reducers work? In this article, we first want to discuss the structure to better understand its mechanism, and then we will take a closer look at all the different advantages and applications of a planetary gear reducer.

The Structure of Planetary Gear Reducers

The main transmission structure of planetary gear reducer is planetary gear, sun gear, and ring gear. The sun gear driven by an external power is located in the center of the ring gear. The planetary gear reducer is composed of a gear (sun gear) rotating around a fixed shaft and a meshing gear (planetary gear) rotating around a sun gear. The ring gear is in close contact with the internal gearbox housing. Between the sun gear and the ring gear, there is a planetary gear set, which consists of three gears equally distributed on the so-called planet carrier.

These three gears are directly supported by the output shaft, the ring gear and the sun gear that is floating in it. When the sun gear is driven by the input power, the planetary gear will be driven to rotate, and then rotate around the center together with the orbit of the ring gear.

Advantages of Planetary Gear Reducers

If you want to achieve high torque while reducing the processing speed, then a planetary gear reducer might be your ideal choice. In real life, you'll find planetary gear reducers not only in small machines like electric screwdrivers but also in large machines like bulldozers. Planetary gear reducers 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 a planetary gear reducer:

1. High Power Density 
On a planetary gear reducer, 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 efficacy. This leads to higher power density.

2. High Efficiency
A planetary gear reducer is highly efficient which is due to its unique design. 
3. Compact Size and Low Weight 
Planetary gear reducers also have a very compact design compared to other speed reducers and as a result, usually weigh less than other types. With a planetary gear reducer, you can achieve as much as a 50% size reduction while maintaining the same torque output.

4. Durability & Longer Product Life
Thanks to the torsional rigidity and better rolling properties of planetary gear reducers, they usually last longer and 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.

5. 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 this results in higher precision and therefore increased repeatability.
6. Increased Precision
On planetary gear reducers, multiple planets or airplanes share the load instead of one gear. The more planets, the greater the load sharing. This leads to higher power density.

7. Increased Torque transmission
As more teeth come into contact, the mechanism can transmit and withstand greater torque. Also, a planetary gear reducer transfers the power more evenly.
8. Maximum Versatility
The mechanism of a planetary gear reducer 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 of Planetary Gear Reducer

Planetary gear reducers or gearboxes have the aforementioned benefits of compact size, lightweight, 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 machinery, light industry and textile industry, medical equipment, instrumentation, automobiles, ships, weapons, aerospace, and many other industrial sectors.

Some planetary reducers are specially designed for square flanges, with simple installation in mind, which makes them especially suitable for AC/DC servo motors, stepper motors, hydraulic motors, and others.

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