Planetary Gear Motion

Hey guys!

In this article we will discuss about the mechanism of the Planetary Gear Motion. This mechanism mainly consists of three gears-the Sun gear,the Planet gears and an Internal gear.

The image given on the right side shows the assembling of the gear mechanism.
As you can see the gear in the middle is the sun gear, the gears alongside are the planet gears and the big gear with internal teeth is the internal gear.

The main mechanism of this motion is that the sun gear is rotated with the help of a motor or any rotating mechanism. Due to this the planet gears which are connected to the sun gear also rotate and the internal gear also starts rotating.

Planetary gears are mainly used for precise motion control. In simple words we can provide different torque in the same gear assembly. Along with providing different speeds this assembly is pretty light weight and has many applications in the industry where we have to transmit higher torque in compact spaces. The torque density of this assembly can be varied by changing the number of planet gears. When talking about torque we can also discuss about power transmission. Due to the presence of a varying torque there is power transmission. So another important advantage is power transmission will be quite good. Another advantage of this assembly is that the internal gear and the sun gear are concentric so multiple assemblies can be installed in the same line.These were some of the advantages now let's talk about some of the disadvantages of this system.


When compared to traditional gear assemblies the cost of planetary assemblies are much higher. Also the installation of this assembly must be extremely accurate or else even a slight miscalculation, may lead to failure of the machine in which it is installed.

This system is used in lathe machines,cranes,automobiles,etc.

Given below is the motion simulation of the planetary gear motion on Solidworks 2016 prepared by the author.

The above mechanism consisted of two planet gears. It was the simplest mechanism that a planetary gear assembly can ever have.

More complex assemblies can also be simulated but for now let's keep our study till this assembly.

So in this post we briefly studied about planetary gears and its applications and also we saw a small video of it's simulation on Solidworks 2016. 

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