Tips Sahabat

Planetary Gear: Function, Components & Complete Working

09 April 2025
fungsi planetary gear

For most automatic car drivers, one of the important components of automatic car transmission is certainly familiar, namely the planetary gear. For those who do not know what a planetary gear is, let's look at the function of the planetary gear, the components within it, and how it works in detail as follows. 

Function of Planetary Gear

When hearing the name of this component, you must be wondering why it is called a planetary gear?

So, the definition of a planetary gear is a component in a car that consists of outer gears and inner gears. The naming is because this component has several other components in the form of gears arranged in such a way like the arrangement of planets in the solar system.

The function of the planetary gear is to regulate the engine transmission system so that you can adjust the car's speed whether you want to increase or decrease speed, reduce and apply engine torque, and control the car's movement whether it moves backward or forward.

As explained above, the function of the planetary gear set in automatic transmission plays a very important role in regulating the car's speed. So what are the components in the planetary gear? Check below.

Several Components of Planetary Gear

Car components are very numerous. As previously explained, the planetary gear consists of several components within it. Here are the planetary gear components that you need to know.

1. Sun Gear

The sun gear is the smallest gear in the planetary gear arrangement located in the center.

The function of the sun gear is as the central axis of all other planetary components just like the sun is the axis for the planets in the solar system. 

Basically, the sun gear is designed using a helical gear or spur gear model.

The characteristic of the sun gear that must be known  to distinguish it from other components is the number of teeth that is fewer.

During the working process, the teeth of the sun gear will interlock with the teeth of the planetary pinion and rotate simultaneously.

Read Also: Drum Brake Components, Function & How They Work

2. Planetary Pinion Gear

After knowing the position of the sun gear, you must be curious about the components surrounding the central axis, which interlock with the teeth of the sun gear.

That component is the planetary pinion gear. This component has a smaller diameter than the sun gear and has a framework arrangement known as the planetary carrier. 

The pinion gear is usually surrounded by a ring gear, and the pinion gear surrounds the sun gear. The framework of the pinion gear is usually made of a mixed iron material and at its end, there is a shaft that functions as an axis when the pinion rotates.

3. Ring Gear

The ring gear is the component that surrounds the pinion gear and is located on the outermost part and functions as the largest lever or  binder of all gear set components.

In the automotive world, this component is often referred to as the annulus gear. This component is also considered to have the most gears compared to other gear components. 

Read Also: How the Gearbox Valve Body Works in Automatic Cars

How Planetary Gear Works

After knowing all the components inside the planetary gear, here is the mechanism of how the planetary gear works.

The components inside the planetary gear can work according to the commands received, the three gear components can either hold or rotate. 

If you want to decrease speed, then the ring gear acts as power input, while the sun gear acts as stationary, and the planetary carrier acts as power output.

This happens because the sun gear is held still and the ring gear is allowed to rotate, so the planetary gear responds by reducing speed.

However, if the sun gear is held still, and the planetary gear is rotating, then the power output from the ring gear will increase speed.

Well, that is a complete review of the components, how they work, and the function of the planetary gear. Hopefully, after reading the above review, you will always pay attention to the condition of the planetary gear so that your car's transmission performance is maximized.

If the planetary gear in your car experiences problems, immediately contact a qualified technician or visit the nearest Daihatsu dealer.

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