80641162 bearing project

7/30/2019 80641162 Bearing Project

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BEARING (MECHANICAL)

From Wikipedia, the free encyclopedia

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 theyallow and according to their principle of operation as well as by the directions of applied loadsthey can handle.

CLASSIFICATION OF BEARING

1. Depending upon the direction of load to be

supported.Radial Bearing

R adial bearings are widely used in various industrial applications. R adial bearings are suitable bearing arrangement, used to carry loads perpendicular to the axis of the rotation. They are

designed to carry both radial and axial (thrust) loads. R adial bearings support rotating shafts.Also known as sleeve bearings, radial bearings can either be full journal bearing or partial journal bearing. The full journal radial bearing has 360 degree contact with its mating surface

whereas the partial journal radial bearing has less than 180 degree contact.

The radial ball bearings are most common and widely used across many industries for their versatility and durability.

Physical Characteristics of Radial Bearings

y These bearings have one row of balls; also known as

single row.y It has two rings namely an outer and an inner ring, which

is placed inside the outer ring.y The inner ring is placed in such a way that it touches the

outer ring at one point with the rings oriented in the

same direction.y A crescent-shaped open area is formed between the rings.y With relation to the outer ring, the inner ring is snapped back to its original position.

y The retainer is fitted in place and the balls are evenly distributed in the raceway.y The balls settle to the deepest point of the raceway when a radial load is applied to the

bearing.y



Advantages of Radial Ball Bearings

y Corrosion resistant

y Lightweighty

N

on-metallic and non-magnetic with glass ballsy Maintenance freey Low friction

y Lubrication freey Bearing and application integration

y Hygienicy Design flexibility

y Low inertia- freer turning

Applications Of Radial Ball Bearings

y Manufacturing aircraft components such as engines, wing flaps, rod-ends, wing mountsand hatches.

y Motors, hand tools, fans, etc.y Helicopters, trains and automobiles, functioning as joints.

THRUST BEARING

A

self-aligning roller thrust

bearing



A thrust ball bearing

A fluid film thrust bearing

A thrust bearing is a particular type of rotary bearing. Like other bearings they permit rotation between parts, but they are designed to support a high axial load while doing this.

Thrust bearings come in several varieties.

y Ball thrust bearings, composed of ball bearings supported in a ring, can be used in low thrust

applications where there is little radial load.

y Roller thrust bearings consist of small cylindrical rollers arranged flat with their axes pointing to

the axis of the bearing. They give very good carrying capacity and are cheap, but tend to wear

due to the differences in radial speed and friction is higher than with ball bearings.

y T apered r oller bearings consist of small tapered rollers arranged so that their axes all converge

at a point on the axis of the bearing. The length of the roller and the diameter of the wide and

the narrow ends and the angle of rollers need to be carefully calculated to provide the correct

taper so that each end of the roller rolls smoothly on the bearing face without skidding. These

are the type most commonly used in automotive applications (to support the wheels of a motor

car for example), where they are used in pairs to accommodate axial thrust in either direction,



as well as radial loads. They can support rather larger thrust loads than the ball type due to the

larger contact area, but are more expensive to manufacture.

y F luid bearings, where the axial thrust is supported on a thin layer of pressurized liquidͶthese

give low drag.

y Magnetic bearings, where the axial thrust is supported on a magnetic field. This is used where

very high speeds or very low drag is needed, for example the Zippe-type centrifuge.

They are commonly used in automotive, marine, and aerospace applications.

Thrust bearings are used in cars because the forward gears in modern car gearboxes use helicalgears which, while aiding in smoothness and noise reduction, cause axial forces that need to be

dealt with. The double helical or herringbone gear balances the thrust caused by normal helicalgears.

One specific thrust bearing in an automobile is the clutch "throw out" bearing, sometimes called

the clutch release bearing .

Fluid-film thrust bearings were invented by Australian engineer George Michell (pronounced

Mitchell) who patented his invention in 1905. Michell bearings contain a number of sector-shaped pads, arranged in a circle around the shaft, and which are free to pivot. These create

wedge-shaped regions of oil inside the bearing between the pads and a rotating disk, whichsupport the applied thrust and eliminate metal-on-metal contact.

2. Depending upon the nature of contact.

a. Sliding Contact bearingy Sliding contact bearings are referred to as plain bearings.

*The bearings are classified broadly into two categories based on the type of contact

they have between the rotating and the stationary member

a. Sliding contact

b. Rolling contact

The sliding contact bearings having surface contact and are coming under lower kinematic pair.

Go through the source link for more information on sliding contact bearing.

-Bearings that provide sliding contact fall into three general classes: radial bearings that support

rotating shafts; thrust bearings that support axial loads on rotating shafts; and linear bearings thatguide moving parts in a straight line. Radial bearings are also called sleeve bearings and they

can either be full journal bearing or partial journal bearing. The former has 360° contact with its

mating surface where the latter has less than 180° contact. The relative motions between the

mating surfaces of a plain bearing may take place in the following ways:

1. As pure sliding with any lubricating medium between the moving surfaces.

2. With hydrodynamic lubrication where a f ilm buildup of lubricating medium is produced.

3. With hydrostatic lubrication where a lubricating medium is introduced under pressure between



the moving surfaces.

4. With a combination of hydrodynamic and hydrostatic lubrication.

y Source(s):

Rolling-element bearing

From Wikipedia, the free encyclopedia

Four-point-contact radial ball bearings

A rolling-element bearing, also known as a rolling bearing,[1]

is a bearing which carries a load by placing

round elements between the two pieces. The relative motion of the pieces causes the round elements

to roll with very little rolling resistance and with little sliding.

One of the earliest and best-known rolling-element bearings are sets of logs laid on the ground with a large

stone block on top. As the stone is pulled, the logs roll along the ground with little sliding friction. As each log

comes out the back, it is moved to the front where the block then rolls on to it. It is possible to imitate such a

bearing by placing several pens or pencils on a table and placing an item on top of them. See " bearings" for

more on the historical development of bearings.

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. As the shaft turns, each roller acts as the logs in the above example.

However, since the bearing is round, the rollers never fall out from under the load.

Rolling-element bearings have the advantage of a good tradeoff between cost, size, weight, carrying capacity,

durability, accuracy, friction, and so on. Other bearing designs are often better on one specific attribute, but

worse in most other attributes, although fluid bearings can sometimes simultaneously outperform on carrying

capacity, durability, accuracy, friction, rotation rate and sometimes cost. Only plain bearings are used as widely

as rolling-element

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