Contenu
What do Rollerblades, fishing reels, bicycle wheels and air conditioners have in common? They all use something called bearings to help their parts spin around. In fact, most anything mechanical that spins around uses one type of bearing or another. Two very common types are the ball bearing and the roller bearing. While their purposes are essentially the same (to help things spin around), the design, function and uses of each are different.
Operation
Both ball bearings and roller bearings work by rolling between two surfaces to reduce friction. The concept is based on the fact that things roll more easily and with less effort than if you slide them. Imagine attaching a rope to a concrete block and pulling it across a sidewalk. Now imagine pulling that same block across marbles that have been scattered on the sidewalk. The block would move much more easily because the marbles have acted as ball bearings.
History
Ancient Egyptian hieroglyphics have been discovered that show large blocks, presumably used to build monuments for the Pharaohs, being pulled across tree trunks acting as roller bearings. Later, in the 15th century, Leonardo Da Vinci described and designed a type of ball bearing, according to the American Bearing Manufacturers Association. The turning point in the development of the bearing was the industrial revolution, when a variety of types of bearings were designed to fill different needs.
Design
By changing the size and shape of a bearing, you change characteristics such as how fast it spins and how much weight it can support. The design determines what type of use the bearing suits. For example, in some applications, simply ensuring that a component is able to spin is sufficient. In others, the need to provide strength and stability along with a spinning motion is essential, which is the case with an automobile wheel. Because of this versatility, bearings are used in many applications in the home as well as industry.
Comparisons
Ball bearings are by far the most common type of bearing and are used in everything from dishwashers and washing machines to blenders and computer hard drives. They provide the ability to spin and a small to medium amount of weight-bearing support. Because their design does not allow large amounts of weight to be supported, they are most commonly used in household appliances and tools. Roller bearings are shaped like cylinders and are most commonly used in heavy machinery or industrial applications. Conveyor belt rollers in factories use this type of bearing because, unlike the ball bearing, where any weight pushing down on it is focused on one point, weight is spread out in a line along the surface of the bearing. This allows the roller bearing to handle much more weight and makes it ideal for heavy-duty applications.
Summary
Although ball bearings and roller bearings are two of the most common, there are thousands of types used for a multitude of purposes. Many of these are standard designs, while others are custom-made to fit the needs of a particular application. Whatever the use, all combine the characteristics discussed above. Because of the versatility and applicability of this simple, yet highly functional, device, we have the freedom to enjoy countless pleasures that we tend to take for granted.
