In order for a wheel to rotate, it needs to move. In order for a wheel to move, it must be connected to an axle. However, the axle also needs to be able to rotate – but how can something constantly rotating constantly moving? A bearing! Bearings are a piece of technology that allow axles and wheels (and other objects) constantly rotating constantly moving, allowing them do their jobs with ease and without getting worn down.
Bearings come in two varieties: rolling-element bearings and plain bearings. Rolling-element bearings use components that can roll easily, such as ball bearings or roller bearings, while plain bearings contain static components which only support lateral movement. There are many different types of both rolling-element bearings and plain bearings; examples include ball bearing, roller bearing (axle), sleeve bearing, needle bearing (screwdriver), etc. Bearings are also found in many moving objects besides axles, such as conveyor belts, gears, locks, the steering mechanism of a car or bike wheel.
Bearings allow things to rotate freely because the friction generated between rotating components is greatly reduced. This friction reduction is accomplished through the two methods mentioned above: rolling elements and lateral support. Rolling-element bearings’ components have a very low coefficient of static friction allowing them to spin easily about one another with almost no force at all. In wheeled vehicles, rubber tires provide this type of “lateral support” allowing the wheel to stay centred in the axle well, instead of binding to it. This lateral support allows for smooth rotation without much force at all.
Why are housed bearings so useful?
Bearings (which can also be called journal bearings or roller bearings) are used in all sorts of machinery, like the tiny ball bearing in a mechanical wristwatch, to the enormous bearings that support the weight of oil rigs. It is because they are so useful that most children will have seen them before in some form, although not under the name “bearings”. But their usefulness comes from two facts: Firstly, they provide lubrication. Surprisingly enough, they actually reduce friction by separating moving parts with a thin layer of grease or oil! Secondly, they reduce impact forces on surfaces that rub together. This means that they keep your car’s axles running smoothly and without vibration. Bearings are also often found in electrical appliances – even if you don’t see them, they are there! They allow hard disks to spin quickly and quietly. Bearings are also found in exercise equipment like treadmills; without bearings, it would be very difficult to balance the load on your legs as you run or walk. Bearings can take any number of forms, but all share the same principle: separating surfaces by putting something between them.