Gear Train | Definition, Types, Applications [Explained with Animation]

In this article we will learn Gear trains and their types

What is a Gear train?

A Gear train is a combination of Gears which is used when we have to obtain large velocity reduction (or vice versa) in a limited space

Gear trains are used in almost all machines which are dealing with the mechanical power. Some of the places where gear trains are used are engines, lathes, clocks, gear box and Differential of automobiles etc.

Types of Gear trains

Generally, there are four types of Gear trains

1. Simple Gear train
2. Compound gear train
3. Reverted gear train
4. Planetary or epicyclic gear train

Let us understand each type of gear train with the help of explanation and images.

Simple gear train

Characteristics of simple gear train

• Gears are in the form of series
• Axes of gears remains fixed
• Each gear is mounted on different shaft

Compound gear train

Characteristics of compound gear train

• All the characteristics are same as simple gear train except that more than two gears can also be mounted on a single shaft

Reverted gear train

Characteristics of reverted gear train

• All the characteristics of the reverted gear train are same as compound gear train except that the axis of shafts on which first and last gear is mounted coincides
  

  Reverted gear train

In the above gear arrangement (top view is shown here) the gears with the shafts are the first and last gear of the arrangement. You can see easily that their center line coincide.

Planetary or epicyclic gear train

Characteristics of planetary or epicyclic gear train

• As the name suggests, it is a type of gear train in which at least axis of one of the participating gear’s shafts rotates with respect to other’s

With the help of above animation one can easily understand working of planetary or epicyclic gear trains.

Examples of epicyclic gear train

• Sun and planet gear
• Bevel epicyclic gear
• Compound epicyclic gear

Image attribution: By Laserlicht – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=49080501