Introduction to Gears

Context

We cannot have high torque and speed at the same time. This can be explained as follows:

• Power = Torque x Speed• Power supplied to motor is constant, so if we increase torque we reduce

speed and vice-versa. Therefore, there has to be a trade- off as per the requirements.

• RPM of the motors is constant. So, in order to increase torque, we should reduce rpm by bringing in some external system.

• So what is the solution to reduce rpm? Well, it can be achieved by using GEARS.

Why Gearing?

Gears are required for the following reasons:

• Decrease/Increase Speed (RPM)

• Increase/Decrease Torque

• Transmission of Force along another axis

RPM stands for Revolution per minute

What is a Gear?

A gear is simply a rotating machine (made of metal or plastic) with a number of cut teeth on it.

Gearing

Attach a small gear to a large gear. The teeth of both the gears mesh with each other to transmit torque.

Example: Two gears touching each other

Explanation of Example:

The small gear having 15 teeth is directly driven by a motor. For each revolution of the small gear, the large gear turns one-half a revolution. Expressed in another way, if the motor and small gear turns at 1000 rpm, the large gear turns at 500 rpm. Thus, speed is reduced and halved. Torque gets doubled. The gear ratio is said to be 2:1. This arrangement enclosed in a casing is called a gear box.

DC Geared Motor

A simple DC motor with an in-built gearbox is called a Gearhead or Geared motor. Geared motors give reduced speed and increased torque. With more torque, robot can also handle heavy loads.

DC Geared Motor

Some disadvantages of using gear motors are:

• Increase in noise level

• Increase in overall weight

• Increase in overall length

• Increase in no load current

Thank you