Bearing is one of the best invention of human being, which not only make work easy for humans but also reduce power and increase the life of movable parts. Some form of bearings is used from ancient times, but actually bearing is invented around 17th century. In 1974 Philip Vaughn got patent for first ball bearing.
Word bearing is come from "to bear", as it bear load and friction.
Bearings are used in every rotational part from big turbines to small toys for kids, it is used in industries as well as household applications, used by farmers and doctors. Every day we use bearings in one or other form. Their is huge range of bearings, one bearing is so small that it can fit on nail of little finger, other one is so big that a human being can easily cross from inside. Bearings are used in every application where rotation is involved, but Still we are not aware about bearings because bearing is usually fit inside and is packed, so it is not easily seen by people unless until the instrument or product is damage or making sound, during repair only we can able to see bearings.
It will be interesting to know that a single car has more than 100 bearings fitted inside.
Why bearings are so important?
1. Bearings reduce the friction of rotational part:
When any two parts move together it create friction when we use bearing bear load and reduce the friction between the two parts hands reduce the fractions of rotational parts. As a result consumption of power also reduce.
2. Increase the life of rotational part:
As the friction between two parts reduce the wear and tear of the parts will also reduce with results into more life of the part s a result the cost of maintaining the part or the device reduce.
3. Maintain the alignment of rotational part:
Is bearing maintain the load due to which wear and tear of the rotation part reduce, this result into maintaining the the alignment of the rotational part, due to this parts remain in its position for a longer period of time.
Parts of Bearings:
Before we know about the types of bearings, it is important to understand how many parts are used to make a bearing.
Minimum four parts are essential to make a bearing but 5th and 6th part is used when their is any specific requirements.
1. Inner ring
2. Outer ring
3. Cages
4. Ball or rollers
5. Shields
6. Lubricants
1. Inner ring & outer ring:
Inner ring and outer ring are two raceways, these two rings are very important for the fitment. For the manufacturing of bearings in a diameter and outer diameter is one of the most critical part of the bearing (w.r.e. quality)
2. Cages:
Cages are ribs of the bearings, as it protect rolling elements not to move out from the bearing. Cages also help to maintain distance between rolling elements, so that they don't collide with each other and hence helps in free movement. Initially cases are made from sheet metals but nowadays some bearings have cages that are made from nylon sheets.
3. Balls or rollers:
Balls are rollers are the rolling element of the bearings, most of the bearings are made from Steel balls but in recent researches they are made from ceramic balls that work in very high temperature especially for EV vehicles. Rolling element bear complete load of the bearing.
4. Sheild:
Shield protect dust to enter inside the bearings. It also prevents lubricants not to move out of the bearings.
5. Lubricants:
Lubricants are used to reduce the friction between the inner and outer races and balls or rolling element it also reduce temperature during its motion as the friction is reduced it will increase the life of the bearing.
Different types of bearings:
Basically there are two type of bearings (based on rolling elements) and there four sub part of each of them.
1. Ball Bearings
1.1 Deep groove ball bearing
1.2 Self aligned ball bearing
1.3 Angular contact ball bearing
1.4 Thrust ball bearing
2. Roller Bearings
2.1 Tapper roller bearing
2.2 Spherical roller bearing
2.3 Cylindrical roller bearing
2.4 Needle roller bearing
Ball bearing:
Ball bearing is the simplest form of bearings. It is designed to work at high speed but it is not able to hold heavy load because of balls, balls are used as rolling elements between inner and outer race.
Types of ball bearings:
1.1 Deep groove ball bearing:
Mostly deep groove ball bearing is know as ball bearing. Because of it's simple design it is most widely used bearing in the word. This bearing can handle radial load and axial load in both the direction. Deep groove ball bearing is used in almost all the home appliances like fans, toys, etc.
1.2 Self aligned ball bearing:
As the name suggest self aligned ball bearing is able to align itself with respect to the application where shaft and housing not aligned properly or there is some deflection during the mounting or during the use. This bearing can able to handle or adjust mis-alignment up to 3°. This bearing has low capacity to handle load but but handle static and dynamic load.
Self aligned ball bearing has a inner race with two raceways or track, double rows of balls (rolling element) fixed with cage and special outer race has spherical design. This spherical design allows inner ring and balls to swivel within outer ring.
1.3 Angular contact ball bearing:
As the name suggest angular contact ball bearing handle a load at an angle. In this pairing inner ring raceway and outer ring raceway transfer there load at an angle and as the angle increase the load carrying capacity also increase.
Inner ring and the outer ring has an offset from each other at the axis, as a result can handle axial and radial load simultaneously. These bearings are used where high speed, high axial load and precised work has to be done, like in machines and gearboxes⚙️.
Angular comes in two forms.
1. Single angular contact bearing: These type of bearings have high thrust carrying capacity in one direction.
2. Double angular contact bearing. These types of bearings can carry Thrust in both directions.
1.4 Trust ball bearing:
Thrust ball bearings are special design bearings which are manufactured to accumulate axial load, thrust ball bearing does not supposed to used where we require to carry or bear radial load.
Thrust ball bearing can be classified on the basis of application and design.
On the basis of design trust ball bearings has two types:
1. Single direction trust ball bearing: these bearings consists of two ring (shaft and housing washer) and one ball & cage assembly.
2. Double direction thrust ball bearing: these bearings consists of three washers and two ball & cage assembly and separated by shaft washer.
On the basis of application thrust ball bearings is also of two types:
1. Flat thrust ball bearing: these bearings are used in application we required only axial load.
2. Spherical thrust ball bearing: these bearings are used in application where we also require to handle mis-alignment of the shaft.
Roller bearings:
As the name suggested rollers where used as rolling element in this type of bearings. Roller bearings are special design bearings which are used to carry high load and but works where lower rotational speed as comparison to ball bearing of similar size.
Types of Roller bearings:
2.1 Taper roller bearings:
This bearing is called as taper roller bearing as both inner race (called as cone) and outer race (called as cup) are in Tapper shape and roller used as rolling element is also in Tapper shape. This type of bearings are used to accumulate axial load and radial load simultaneously. By adjusting the angle of cup and cone load can be adjusted. As we increase the angle the axial load carrying capacity increase. Tapper roller bearing are most used roller bearing.
2.2 Spherical roller bearings:
Spherical roller bearing some what similar to self aligned ball bearing as this also has self aligned capacity. This type of bearings are used in application where heavy axial and radial load are required and there may issue of mis-alignment in the shaft. As this bearing has high load carrying capacity and also accumulate misalignment, these features helps bearing to increase its life and also reduce maintenance cost. These are used in paper milles, big conveyors, gearboxes ⚙️.
2.3 Cylindrical roller bearings:
Cylindrical roller bearings are used where high speed and heavy load is required, this is possible because of line contact between roller and raceways. These bearings are low noise bearings as compared to other roller bearings and also readuce low heat during running in different applications. Cylindrical roller bearings have high stiffness, low friction, and long service life as they accommodate axial displacement.
Different versions of Cylindrical roller bearings are N, NU, NUP, NJ.
2.4 Needle roller bearings:
Needle roller bearings are called so because roller used are thin, diameter are very small as compared to length of roller. Due to thin diameter of roller, many roller are used in these bearings, this feature increase the stiffness and load carrying capacity. Diameter of roller is three to ten time smaller than the length of roller. These bearings are used where high radial load is required. These bearings are used in AC compressors, transmission application of automobile.
2.5 Thrust roller bearings:
Similar to thrust ball bearing it is also used to carry axial load and not supposed to used at areas where radial are used. Thrust roller bearings can handle heavy axial load as compared to thrust ball
bearing, but these bearings are not designed to work in high speed.
On the basis of design thrust roller bearings are classified into mainly Four types:
1. Cylindrical thrust roller bearings.
2. Spherical thrust roller bearings.
3. Tapped thrust roller bearings.
4. Needle thrust roller bearings.
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