Bearing (mechanical)

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BallBearing

Bearing (mechanical)

A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; it may also prevent a motion by controlling the vectors of normal forces that bear on the moving parts.

Types of Bearings

Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts. The most common types include:

• Plain bearing
• Rolling-element bearing
• Jewel bearing
• Fluid bearing
• Magnetic bearing
• Flexure bearing

Plain Bearings

Plain bearings, also known as bushings, journal bearings, or sleeve bearings, are the simplest type of bearing, comprising just a bearing surface and no rolling elements. They are used in a wide variety of applications.

Rolling-Element Bearings

Rolling-element bearings, such as ball bearings and roller bearings, use rolling elements placed between the races, or journals, of the bearing assembly. The rolling elements can be balls, cylindrical rollers, spherical rollers, tapered rollers, or needle rollers.

Jewel Bearings

Jewel bearings are plain bearings in which a metal spindle turns in a jewel-lined pivot hole. They are used in precision instruments, such as watches, because they have very low and predictable friction.

Fluid Bearings

Fluid bearings are bearings that support their loads solely on a thin layer of liquid or gas. They are used in high-speed applications where ordinary ball bearings would have a short life or cause too much noise.

Magnetic Bearings

Magnetic bearings support moving parts without physical contact. They are used in applications where very high speeds or very low friction are required.

Flexure Bearings

Flexure bearings are designed to allow motion by bending a load element. They are used in applications requiring precise positioning and low friction.

Applications

Bearings are used in a wide range of applications, from household appliances to industrial machinery. Some common applications include:

• Automobiles
• Aircraft
• Electric motors
• Hard disk drives
• Medical equipment

Maintenance

Proper maintenance of bearings is crucial for the longevity and performance of machinery. This includes regular lubrication, cleaning, and inspection for wear and damage.

Related Pages

• Tribology
• Lubrication
• Friction
• Wear
• Machine element