What Are Bearings Used For?

Bearing is an important part of modern mechanical equipment.  
Its role should be support, that is, literal interpretation used to bear the shaft, but this is only a part of its role, support its essence is able to bear radial load.  You can also understand that it's used to fix the axis.  It is fixed axis so that it can only achieve rotation, and control its axial and radial movement.  
Bearing the role of a support role, namely if the transmission parts (such as: shaft) directly cooperate with hole, a driving resistance is big, and the wear big, transmission is not easy to change, and bearing is rely on rolling contact between components to support the transmission parts, so the sliding resistance is small, less power consumption, starting easily, etc.  
The main function is to support the mechanical rotating body, reduce its friction coefficient in the process of movement, and ensure its rotation accuracy.  It can be understood that it is used to fix the axis, so that it can only achieve rotation, and control its axial and radial movement.  If the shaft has no bearings it will not work at all.  Because the axis can move in any direction, and the work requires that the axis can only rotate.  
Bearings are widely used in automobiles: rear wheels, transmission, electrical components.  
Electrical: general motors, household appliances.  Instrumentation, internal combustion engine, construction machinery, railway rolling stock, loading and unloading machinery, various industrial machinery.  Machine tool spindles, agricultural machinery, high frequency motors, steam turbines, centrifuges, small car front wheels, differential pinion shafts.  
Oil pump, Roots blower, air compressor, all kinds of transmission, fuel injection pump, printing machinery, motor, generator, internal combustion engine, steam turbine, machine tool spindle, reducer, loading, unloading and handling machinery, all kinds of industrial machinery, etc.  Almost as long as it is rotating rotating are used to bearings. 
Bearing parameters  
Life  
Under a certain load, the number of revolutions or hours that the bearing experiences before pitting corrosion is called the bearing life.  
The life of a rolling bearing is defined in revolutions (or hours of operation at a given speed) : a bearing within this life shall have initial fatigue damage (spalling or defect) on any of its bearing rings or rolling bodies.  However, whether in laboratory tests or in actual use, it can be obviously seen that the actual life of bearings with the same appearance under the same working conditions is very different.  In addition, there are several different definitions of bearing "life", one of which is the so-called "working life", which means that the actual life of a bearing can be achieved before damage is caused by wear, damage is usually not caused by fatigue, but by wear, corrosion, seal damage and other reasons.  
Due to the difference in manufacturing accuracy and material uniformity, even if the same material and the same size of the same batch of bearings are used under the same working conditions, their service life is not the same.  If the statistical life is 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, and the ratio between the longest and the shortest life is 20-40 times.  90% of bearings do not produce pitting corrosion, and the number of revolutions or hours experienced is called the bearing rated life.  
Rated dynamic load  
In order to compare the bearing capacity against pitting corrosion, it is stipulated that the maximum load that can be borne when the rated life of the bearing is one million revolutions (106) is the basic rated dynamic load, represented by C. 
That is, under the action of rated dynamic load C, the reliability of this bearing working for one million turns (106) without pitting failure is 90%, and the greater the C, the higher the carrying capacity.  
Bearing classification  
Sliding bearin :sliding bearing has no inner and outer rings and no rolling body. It is generally made of wear-resistant materials.  It is usually used for low speed, light load, lubricating oil filling and mechanical rotating parts which are difficult to maintain.  
knuckle bearing: the knuckle bearing contact surface of plain bearing is spherical, which is mainly suitable for swing motion, inclined motion and rotary motion.  
Rolling bearing  
Rolling bearings are divided into centripetal bearings and thrust bearings according to their load direction or nominal contact Angle.  The radial contact bearings are centripetal bearings with nominal contact angles of 0 and centripetal angular contact bearings with nominal contact angles greater than 0 to 45.  Axial contact bearings are thrust bearings whose nominal contact Angle is 90, and thrust angular contact bearings whose nominal contact Angle is greater than 45 but less than 90.  
According to the shape of the rolling body can be divided into ball bearings and roller bearings.  Roller bearings are divided into cylindrical roller bearings, needle roller bearings, tapered roller bearings and self-aligning roller bearings.  
According to its work can be divided into self-aligning bearings ---- raceway is spherical, can adapt to the angular deviation and angular motion between two raceway axis line bearings and non-self-aligning bearings (rigid bearings)---- can resist the angular deviation between raceway axis line bearings.  
According to the column number of the rolling body, it is divided into single row bearings, double row bearings and multiple row bearings.  
According to its components (rings) can be separated into separable bearings and non-separable bearings.  
According to its structure shape (such as whether there is a filling groove, whether there is an inner ring, outer ring and the shape of the ring, the structure of the guard edge, and even whether there is a cage, etc.) can also be divided into a variety of structural types.  
Its outer diameter size is divided into miniature bearings (<26mm), small bearings (28-55mm), small and medium bearings (60-115), medium and large bearings (120-190mm), large bearings (200-430mm) and very large bearings (>440mm).  
According to the application field, it can be divided into motor bearings, rolling mill bearings and main bearings.  
According to the material is divided into ceramic bearings, plastic bearings and so on.