Types of Bearings

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 first plain and rolling-element bearings were wood, but ceramic, sapphire, or glass were also used, and steel, bronze, other metals, ceramics, and plastic (e.g., nylon, polyoxymethylene, polytetrafluoroethylene, and UHMWPE) are all common today. A "jeweled" pocket watch uses stones to reduce friction, and allow more precise time keeping. Even old materials can have good durability. As examples, wood bearings can still be seen today in old water mills where the water provides cooling and lubrication.The first practical caged-roller bearing was invented in the mid-1740s by horologist John Harrison for his H3 marine timekeeper. This uses the bearing for a very limited oscillating motion but Harrison also used a similar bearing in a truly rotary application in a contemporaneous regulator clock.

Fluid and magnetic bearings can potentially give indefinite life. In practice, there are fluid bearings supporting high loads in hydroelectric plants that have been in nearly continuous service since about 1900 and which show no signs of wear.

A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle.

[07/13/10]Agricultural Bearing(PART II)

[07/13/10]Agricultural Bearing(PART I)

[07/12/10]Cylindrical Roller Bearing