More about SKF bearings Bearings basics Friction Protection Lubrication Robustness Precision / ABEC Mounting / Removing Cleaning		Bearings basics     Different bearing types There are more than one hundred bearings types with different shapes and designs. To simplify they can be divided in two main families, ball bearings and roller bearings. Roller bearings are generally used in high-load applications. They are often found in industrial applications, mainly as large size bearings. For skates both inline or quads, or for skateboards one will never find roller bearings but only ball bearings; more specifically deep groove ball bearings. To simplify, we will call them ball bearings in the following pages. Ball bearings are the simplest and most popular bearings. They are found in large variety of applications, such as cars, air dryers, washing machines, lifts, etc. Therefore SKF ensures to have worldwide availability. Further, as most popular ones, they also have an attractive price. What is a ball bearing? A ball bearing consists of following parts: An outer ring An inner ring A number of balls A cage Lubricant (for sealed bearings) Protection (sealing) What is a ball bearing made for? Ball bearings ensure a mechanical link between a rotating part and a stationary part. For example: ball bearings are used to guide and maintain the wheel that is rotating relative to the axle that is fixed on the frame. The internal design of the bearing ensures the wheel to have low friction and precise rotation. But we will come back later on that subject. When did ball bearings appear? Leonardo da Vinci has drawn the first ball bearings in the 15th century. First prototypes have been made in wood. In the early 18th century, scientists have thought to make them of steel and to use them in transport systems. Nevertheless it's only towards the end of the 19th century that ball bearings have been made to acceptable quality and produced in quantities for applications such has railways, industrial steam machines, and cars. At that time, bearing manufacturers made bearings to any dimension, this created a lot of problems of interchangeability. After world war 1 the bearing manufacturers begun to think about standards, in order to standardize bearing sizes, and to define the main characteristics. Though, in the 50's, appeared the ISO (International Standard Organization) standard systems. These are the only international standards to describe bearing dimensions and main characteristics. For example this explains why a ball bearing of dimensions 8x22x7 mm is called 608. Sometimes, like for inline skate bearings, ancient American ABEC standards are still being used. Who is manufacturing ball bearings? Of course SKF does! Since the beginning the ball bearing industry was considered as strategic by all industrialized countries. The bearing industry has become really international over the past 20 years, with worldwide companies able to provide the complete bearing range. There are 5 important ball bearing manufacturers, said to have high quality and serious technology. Not all of them produce 608 or mini-bearing sizes like SKF does.
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