Gears and Chains

Whenever, you make a robot mechanism, you almost always need a power source. Whether it is motors, servos, rubber bands, or controlled gravity. In many instances, the simple output of the power source must be 'modified" or "moved" in order to accomplish a task (claw, bin, arm, self destruct switch). In this article, I will be discussing how you can do this is through gears and chains.

(The first few paragraphs cover the basics, later paragraphs may cover more advanced topics, like differential drives, alternating gear shifts.)


Gears are simply discs with teeth, almost attached to an axle to produce rotation. Gears vary by the number of teeth and their diameter (size). This difference of size is usually referred to as a "ratio". Using gears of various ratios, you can do many useful things.

"Ratio Gear Chains"

By using ratios, you can do two things, you can increase either the speed or the "strength" of the motor, also known as "gearing up" and "gearing down" respectively. In these examples, you will be referring to two gears, the "power gear" and the "wheel gear". The power gear is attached to a motor, while the wheel gear is attached to... a wheel.

"Gearing Up"
- Increase speed
- Decrease strength (torque)

By using a big power gear and a small wheel gear, you can increase the speed of the wheel. When the large gear makes one rotation, the small gear makes multiple. The wheel gear spins faster then the power gear, making your robot move faster (ignoring acceleration, weight, center of gravity, etc). However, the force of the motor is "spread out" on the large gear, making the strength lower.

pic of gearing up

"Gearing Down"
- Increase strength (torque)
- Decrease speed

By using a small power gear and a big wheel gear, you can increase the strength of the wheel. When the small gear makes one rotation, the large gear makes a partial rotation. The wheel gear moves slower than the power gear, making the robot move slower. However, the force of the motor is "more concentrated" on the small gear, making the strength higher.

pic of gearing down


Thank you so much for this

Thank you so much for this great article games sharing for us and now we can get this site here on this link.

That's interesting Can you

That's interesting
Can you input some picture? Because I want to participate in a robotic competition with my friend. We both in the same school in one of the International School in Indonesia.

BBS - International School in Jakarta with Singapore Curriculum dan Billingual Program .

can u put some pics ?

can u put some pics ?

The amount of increase or

The amount of increase or decrease of strength and speed is the ratio of the number of teeth on each gear.