Question

Explain briefly the differences between simple, compound, and epicyclic gear trains

Answer 1

There are different types of gear trians. They are;

1. Simple Gear Train

2. Compound Gear Train

3. Reverted Gear Train

4. Epicyclic Gear Train

In the first three types of gear trains the axis of the shafts over which the gears are mounted are fixed relative to each other. But in case of epicyclic gear trains, the axis of the shafts on which the gears are mounted may move relative to a fixed axis.

Differences between Simple, Compound and Epicyclic Gear trains:

Simple Gear Train	Compound Gear Train	Epicyclic Gear Train
1. Only one gear in each shaft. 2. There will be relative motion between the shaft axis. 3. For large speed reduction, large size of gear is required.	1. In this gear there is more than one gear on the shaft. 2. The gear is rigidly fixed and meshed with gear on another shaft forming gear train. 3. For large speed reduction, small gear ratio is required.	1. In this gear train they are sun gear, Planet gear and Ring gear. 2. The axis of shaft on which gears are mounted may move relative to the fixed axis. 3. For large speed reduction in high velocity moderate size of gear is required.

For better understanding observe the following images of Simple, Compound and Epicyclic gear trains;