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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; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. 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 simplest form of bearing, the plain bearing, consists of a shaft rotating in a hole. Lubrication is often used to reduce friction. In the ball bearing and roller bearing, to prevent sliding friction, rolling elements such as rollers or balls with a circular cross-section are located between the races or journals of the bearing assembly. A wide variety of bearing designs exists to allow the demands of the application to be correctly met for maximum efficiency, reliability, durability and performance.The term "bearing" is derived from the verb "to bear" a bearing being a machine element that allows one part to bear another.The most sophisticated bearings for the most demanding applications are very precise devices; their manufacture requires some of the highest standards of current technology.


There are Some common types of bearing, each of which operates on different principles:-

Plain bearing: Consisting of a shaft rotating in a hole.
Ball bearing: In which the rolling elements are spherical balls.
Roller bearing: In which the rolling elements are cylindrical rollers.
Magnetic bearing: In which the load is supported by a magnetic field.


Plain bearing:

A plain bearing is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole.Plain bearings, in general, are the least expensive type of bearing. They are also compact and lightweight, and they have a high load-carrying capacity.


Ball bearing:

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls.Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races.


Roller bearing:

A rolling-element bearing, also known as a rolling bearing,is a bearing which carries a load by placing rolling elements between two bearing rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding.
A rolling element rotary bearing uses a shaft in a much larger hole, and cylinders called "rollers" tightly fill the space between the shaft and hole.Rolling-element bearings have the advantage of a good tradeoff between cost, size, weight, carrying capacity, durability, accuracy, friction, and so on.


Magnetic bearing:

A magnetic bearing is a bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear. Magnetic bearings support the highest speeds of all kinds of bearing and have no maximum relative speed.Magnetic bearings are used in several industrial applications such as electrical power generation, petroleum refinement, machine tool operation and natural gas handling.


Maintenance and lubrication


Many bearings require periodic maintenance to prevent premature failure, but many others require little maintenance. Nonsealed bearings often have a grease fitting, for periodic lubrication with a grease gun, or an oil cup for periodic filling with oil.Many bearings in high-cycle industrial operations need periodic lubrication and cleaning, and many require occasional adjustment, such as pre-load adjustment, to minimise the effects of wear.Bearing life is often much better when the bearing is kept clean and well lubricated. a good maintenance program might lubricate the bearings frequently but not include any disassembly for cleaning.

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URL : http://mbp-bearings.com/

Blog ID : 199633

Category : Business

Date Added : 8-5-2017