Gears are used in tons of mechanical devices. They do a number of important jobs, but most significant, they offer a gear reduction in motorized equipment. That is key because, frequently, a little motor spinning very fast can provide plenty of power for a gadget, but not enough torque. For example, an electric screwdriver has a very large gear reduction because it needs lots of torque to turn screws, but the motor only produces a small amount of torque at a higher speed. With a gear reduction, the output speed can be reduced while the torque is increased.
Another thing gears do is usually adapt the direction of rotation. For instance, in the differential between your rear tires of your car, the energy is usually transmitted by a shaft that operates down the guts of the car, and the differential must convert that power 90 
degrees to apply it to the wheels.
There are a great number of intricacies in the various types of gears. In this article, we’ll learn exactly the way the teeth on gears work, and we’ll talk about the different types of gears you find in all sorts of mechanical gadgets.
Basics
On any equipment, the ratio is determined by the distances from the center of the gear to the idea of contact. For example, in a device with two gears, if one gear is twice the size of the other, the ratio will be 2:1.
One of the most primitive types of gears we could look at will be a steering wheel with wooden pegs protruding of it.
The problem with this type of gear is that the distance from the center of each gear to the idea of contact changes as the gears rotate. This means that the gear ratio changes as the apparatus turns, meaning that the output speed also changes. If you used a equipment such as this in your car, it will be impossible to keep a continuous speed — you would be accelerating and decelerating constantly.
Many contemporary gears use a special tooth profile called an involute. This profile gets the very important home of greenhouse reducer maintaining a continuous speed ratio between your two gears. Like the peg wheel above, the contact point moves; but the form of the involute equipment tooth compensates because of this movement. See this section for information.
Now let’s check out some of the various types of gears.