Lesson 14: How Bearings Increase Efficiency (How Things Work)

In this lesson, we will analyze how rolling element bearings aid mechanical components and increase efficiency by reducing friction. These rolling element bearings are found in almost every mechanical device which involves rotation. They are found in cars, carts, windmills, and even yo-yo's.

These bearings function on the principal that it is easier to roll something as opposed to slide something. To verify this, take something flat like a book and push it across a flat surface such as a table. Note how much force is required to push the book. Then place the book on a few cylindrical or spherical objects such as marbles or pencils. Now push the book and notice how much easier the book moves.

When objects slide across surfaces, the force of friction resists e object's motion. However, when something rolls, there is relatively no sliding occurring, so the resistant force of friction is minimized.

Rolling element bearings exploit this fact by placing round objects between two surfaces which would normally come in contact with each other with sliding motion. The inner surface of a rolling element bearing is known as the inner race while the outer surface is known as the outer race. The rolling elements are usually kept separated to reduce sliding with one another by a metallic structure called a cage.

Below is a picture of what a rolling element bearing might look like.