BEARINGS

ASHWANI KUMAR on 10/25/2022 8:29:10 AM

Introduction:


Bearings are a crucial component of many types of machinery and exist in a variety of forms and shapes. They can be defined as a component that permits only a specific type of motion in a system that may be under static or dynamic loading.

A bearing is a precision-made machine component that allows machinery to move at extremely high speeds, while reducing friction between moving parts and handling stress. Most bearings are used to support rotating shafts in machines

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Bearing, in machine is, a connector (usually a support) that permits the connected members to rotate or to move in a straight line relative to one another. Often one of the members is fixed, and the bearing acts as a support for the moving member.


Main function of bearing:

-To reduce friction between moving rotatory parts.

-To support rotating parts of a machine.

-To bear radial and thrust load.

-Minimize maintenance expenses




Components of bearing:

Bearings usually consist of the following components:

-Two rings or discs with raceways

-Rolling elements in the form of rollers or balls

-A cage which keeps the rolling elements apart and guides them


Inner Ring / Outer Ring

The inner and outer ring are usually made from a special high-purity, chrome alloy steel. 

This material has the necessary hardness and purity – both important factors for a high load rating and a long service life.

The raceways are hardened, ground and honed.Special materials such as ceramic and plastics are also used. Although plastics cannot withstand extremely high temperatures, they are considerably lighter than steel. This makes them invaluable in sectors such as the automotive industry, where every gram matters.


Inner ring-      




Outer ring-  






Rolling elements-  




Rolling elements are either balls, rollers, cones, spheres or needles. They are usually made from a special high-purity, chrome alloy steel. Special materials such as ceramic and plastics are also used.

The rolling elements roll on the specially formed raceways of the rings or discs and are kept apart and guided by the cage





Cage-      

The cage is responsible for keeping the rolling elements apart and guiding them. The materials used include steel, brass and plastic. Solid metal cages can be produced using machining techniques, while pressed cages are made from sheet metal. Similarly, plastic cages can be machined from solid plastic or injection moulded.




Types of Bearing


Bearings can be classified based on different criteria, such as design and operating mode, allowed motion, or direction of load. From a design perspective, the classification of bearings is as follows.


Plain Bearings :

Plain bearings, also referred to as bushes, bushings or sleeve bearings, are usually cylindrical in shape and contain no moving parts.

Plain bearings are used for sliding, rotating, oscillating or reciprocating motion

Plain bearing construction may be solid or with a split joint (wrapped bearings) for easier installation.Plain bearings are manufactured with different constructions and product selection depends on the operating conditions of the application and performance requirements.





Ball Bearings :

Ball bearings are one of the most common types of bearing classes used. It consists of a row of balls as rolling elements. They are trapped between two annulus-shaped metal pieces. These metal pieces are known as races. The inner race is free to rotate while the outer race is stationary.

Ball bearings are used for controlling oscillatory and rotational motion. 





Deep-Groove Ball Bearings :

Deep groove ball bearings, paired angular contact ball bearings and cylindrical roller bearings have all been used in various combinations in two bearing cartridge housing assemblies.These deep grooves result in balls that are more stable and can handle higher loads than shallow-groove bearings. They provide low friction, and the deep groove also limits vibration and noise while also providing the ability for some axial load capacity.





Angular Contact Ball Bearings :

These bearings are designed to take an axial thrust as well as radial loads.




Self-Aligning Ball Bearings :

These bearings are self-adjustable and it is not affected by non-centering of shaft deformation flexure of shaft and bearing block, so it can compensate the concentric error caused by these reason.





Roller Bearings :

Roller bearings contain cylindrical rolling elements instead of balls as load-carrying elements between the races.




Double row Spherical Roller Bearings :

Double-row spherical roller bearings are suitable for large radial loads. They can also take some axial loads in either direction. They are usable for medium speeds. Double-row spherical roller bearings have spherical raceways in the outer ring for both rows of rollers. Therefore, they are self-aligning within wide limits and can accept minor misalignment.





Cylindrical Roller Bearings :

These are the simplest of the roller bearings family. These bearings can face the challenges of heavy radial loading and high speed. They also offer excellent stiffness, axial load transmission, low friction, and long service duration




Tapered Roller Bearings :

Tapered roller bearings feature a cup and cone assembly. The cup is comprised of the outer ring and the cone assembly consists of inner ring, rollers, and cage. This bearing construction accommodates combined loads and provides low friction during operation. By adjusting one single row tapered roller bearing against a second tapered roller bearing and applying a preload, a rigid bearing application can be achieved.





Needle Roller Bearings :

Needle roller bearings are bearings with cylindrical rollers that are small in diameter relative to their length.A needle roller bearing is a special type of roller bearing which uses long, thin cylindrical rollers resembling needles.Needle bearings are heavily used in automobile components such as rocker arm pivots, pumps, compressors, and transmissions.





Jewel Bearings :

Jewel bearings provide very accurate, hard surfaces which can support lightly loaded shafts that see mostly intermittent motion.Jewel bearings are used in light rotating applications such as watches, meter movements, gyroscopes, etc. where loads are small and the supported rotating shafts are tiny. Jewel bearings are constructed from a range of synthetics, with ruby and sapphire being particularly common.  






Flexure Bearings :

Flexure bearings, also referred to as pivot bearings, were designed precisely to tackle the design challenge of limited movement rotational assemblies. They are constructed of stainless steel, non-contacting sleeves connected internally by leaf springs. This allows the sleeves to rotate relative to one another without touching or creating any friction.


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