Bearings are the invisible heroes inside many mechanical devices. Learn about all different kinds of bearings, including 5-foot ball bearings that keep buildings on solid footing!

A tapered roller bearing from a manual transmission Have you ever wondered how things like inline skate wheels and electric motors spin so smoothly and quietly? The answer can be found in a neat little machine called a bearing. The bearing makes many of the machines we use every day possible. Without bearings we would be constantly replacing parts that wore out from friction. In this edition of HowStuffWorks, we'll learn how bearings work, we'll …

…a bearing was back when the Egyptians were building the pyramids. They put round logs under the heavy stones so that they could roll them to the building site. This method is still used today when large, very heavy objects like the Cape Hatteras lighthouse need to be moved. Earthquake-Proof Buildings The new San Francisco International Airport uses many advanced building technologies to help it withstand earthquakes. One of these technologies involves giant ball bearings.