BEARING
BASIC OF BEARING
BY SNEHAL PATEL
BEARING
INDEX Page No: CH.1 - Introduction of bearing
4
CH.2 - Types of Bearing
5
CH.3 - Selection of bearing
11
CH.4 - Bearing Loads
15
CH.5 - Maintanance Maintanance of Bearing
16
CH.6 - Application of Bearing
17
FIG. INDEX
Page No:-
2.1
Plain bearing
6
2.2
Ball Bearings
7
2.3
Ball Thrust Bearing
7
2.4
Roller Bearings
8
2.5
Roller Thrust Bearing
9
2.6
Tapered Roller Bearings
9
2.7
Needle Roller Bearings
10 BY SNEHAL PATEL
BEARING
Ch. 1 Introduction :-
1.1
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 they allow and according to their principle of operation as well as by the directions of applied loads they can handle.
The concept behind a bearing is very simple:
Things roll better than they slide. The wheels on your car are like big bearings. If you had something like skis instead of wheels, your car would be a lot more difficult to push down the road. That is because when things slide, the friction between them causes a force that tends to slow them down. But if the two surfaces can roll over each other, the friction is greatly reduced. Bearings reduce friction by providing smooth metal balls or rollers, and a smooth inner and outer metal surface for the balls to roll against. These balls or rollers "bear" the load, allowing the device to spin smoothly.
BY SNEHAL PATEL
BEARING
Ch. 2 Types of Bearing :-
There are many types of bearings, each used for different purposes. These include ball bearings, roller bearings, ball thrust bearings, roller thrust bearings and tapered roller thrust bearings.
The bearing are of following types :
2.1 Plain bearing : 2.1.1 Cylindrical bearing 2.1.2 Shell type bearing 2.1.3 Split bearing 2.1.4 Plummer bearing 2.2 Ball bearing 2.3 Ball thrust bearing 2.4 Roller Bearing 2.5 Roller thrust bearing 2.6
Needle bearing
BY SNEHAL PATEL
BEARING
2.1 Plain bearing :
A plain bearing, also known as a plane bearing or a friction bearing is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore the journal (i.e., the part of the shaft in contact with the bearing) slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.
Fig. 2.1.1
fig. 2.1.2
fig. 2.1.3
2.2 Ball Bearings :
Ball bearings, as shown below, are probably the most common type of bearing. They are found in everything from inline skates to hard drives. These bearings can handle both radial and thrust loads, and are usually found in applications where the load is relatively small.
BY SNEHAL PATEL
BEARING
Fig. 2.2.1
fig. 2.2.2
fig. 2.2.3
In a ball bearing, the load is transmitted from the outer race to the ball, and from the ball to the inner race. Since the ball is a sphere, it only contacts the inner and outer race at a very small point, which helps it spin very smoothly.
2.3 Ball Thrust Bearing :
Ball thrust bearings like the one shown below are mostly used for lowspeed applications and cannot handle much radial load. Barstools and Lazy Susan turntables use this type of bearing.
Fig. 2.3.1
Fig. 2.3.2
Fig. 2.3.3
BY SNEHAL PATEL
BEARING
2.4
Roller Bearings :-
Roller bearings like the one illustrated below are used in applications like conveyer belt rollers, where they must hold heavy radial loads.
In these bearings, the roller is a cylinder, so the contact between the inner and outer race is not a point but a line. This spreads the load out over a larger area, allowing the bearing to handle much greater loads than a ball bearing.
fig. 2.4.1
fig. 2.4.2
fig. 2.4.2
However, this type of bearing is not designed to handle much thrust loading.
A variation of this type of bearing, called a needle bearing, uses cylinders with a very small diameter. This allows the bearing to fit into tight places.
2.5 Roller Thrust Bearing :
Roller thrust bearings like the one illustrated below can support large thrust loads. They are often found in gearsets like car transmissions between gears, and between the housing and the rotating shafts. The helical gears used in most transmissions have angled teeth -- this causes a thrust load that must be supported by a bearing. BY SNEHAL PATEL
BEARING
Fig. 2.5.1
Fig. 2.5.2
Fig. 2.5.3
2.6 Tapered Roller Bearings :
Tapered roller bearings can support large radial and large thrust loads. Tapered roller bearings are used in car hubs, where they are usually mounted in pairs facing opposite directions so that they can handle thrust in both directions.
Fig. 2.6.1
Fig. 2.6.2
Fig. 2.6. 3
2.7 Needle Roller Bearings :
Tapered roller bearings are based on the observation that cones that meet at a point can roll over each other without slipping. In practice, sections of cones are used. BY SNEHAL PATEL
BEARING
The inner and outer ring raceways are segments of cones and the rollers are also made with a taper so that the conical surfaces of the raceways and the roller axes if projected, would all meet at a common point on the main axis of the bearing.
Fig. 2.7.1
Fig. 2.7.2
Fig. 2.7.3
CH. 3 Selection of Bearing :Bearing selection is usually based on a variety of factors such as:
life required. servicing requirements requirements (maintained or maintenance free). load type (constant, cyclic, shock etc). RPM and/or oscillation rate. environment (contamination possibilities). temperature ranges. installation requirements. requirements. BY SNEHAL PATEL
BEARING
3.1 Dimensional limitations :
The allowable space for bearings is generally limited.In most cases, shaft diameter (or the bearing bore diameter) has been determined specifications. ns. according to the machine’s other design specificatio Therefore, bearing’s type and dimensions are determined according to bearing bore diameters. For this reason all dimension tables are organized according to standard bore diameters. There is a wide range of standardized bearing types and dimensions: the right one for a particular application can usually be found in these tables.
3.2
The characteristics, magnitude, magnitude, and direction dir ection of loads acting upon a bearing are extremely variable. In general, the basic load ratings shown in bearing dimension tables indicate their load capacity. However, in determining the appropriate bearing type, consideration must also be given to whether the acting load is a radial load only or combined radial and axial load, etc. When ball and roller bearings within the same dimension series are considered, the roller bearings have a larger load capacity and are also capable of withstanding greater vibration and shock loads.
3.3
Bearing load :
Rotational speed :
The allowable speed of a bearing will differ depending upon bearing type, size, tolerances, cage type, load, lubricating conditions, and cooling conditions. The allowable speeds listed in the bearing tables for grease and oil lubrication are for normal tolerance NTN bearings. In general, deep BY SNEHAL PATEL
BEARING
groove ball bearings, angular contact ball bearings, and cylindrical roller bearings are most suitable for high speed applications.
3.4
The dimensional accuracy and operating tolerances of bearings are regulated by ISO and JIS standards. For equipment requiring high tolerance shaft runout or high speed operation, bearings with Class 5 tolerance or higher are recommended. Deep groove ball bearings, angular contact ball bearings, and cylindrical roller bearings are recommended for high rotational tolerances.
3.5
Bearing tolerances :
Rigidity :
Elastic deformation occurs along the contact surfaces of a bearing’s rolling elements and raceway surfaces under loading. With certain types of equipment it is necessary to reduce this deformation as much aspossible. Roller bearings exhibit less elastic deformation than ball bearings. Furthermore, in some cases, bearings are given a load in advance (preloaded) to increase their rigidity. This procedure is commonly applied to deep groove ball bearings, angular contact ball bearings, and tapered roller bearings.
3.6 Misalignment of inner and outer out er rings :
Shaft flexure, variations in shaft or housing accuracy, and fitting errors. result in a certain degree of misalignment between the bearing’s inner and outer rings. In cases where the degree of misalignment is relatively large, selfaligning ball bearings, spherical roller bearings, or bearing units with self-aligning properties are the most appropriate choices.
BY SNEHAL PATEL
BEARING
3.7
Noise and torque levels :
Rolling bearings are manufactured and processed according to high precision standards, and therefore generally produce only slight amounts of noise and torque. For applications requiring particularly low-noise or low-torque operation, deep groove ball bearings and cylindrical roller bearings are most appropriate.
3.8 Installation and disassembly :
Some applications require frequent disassembly and reassembly to enable periodic inspections and repairs. For such applications, bearings with separable inner/outer rings, such as cylindrical roller bearings, needle roller bearings, and tapered roller bearings are most appropriate. Incorporation of adapter sleeves simplifies the installation and disassembly of selfaligning ball bearings and spherical roller bearings with tapered bores.
BY SNEHAL PATEL
BEARING
CH. 4 Bearing Loads :-
Bearings typically have to deal with two kinds of loading, radial and thrust. Depending on where the bearing is being used, it may see all radial loading, all thrust loading or a combination of both. The bearings that support the shafts of motors and pulleys are subject to a radial load. The bearings in the electric motor and the pulley pictured above face only a radial load. In this case, most of the load comes from the tension in the belt connecting the two pulleys. The bearings in this stool are subject to a thrust load. The bearing above is like the one in a barstool. It is loaded purely in thrust, and the entire load comes from the weight of the person sitting on the stool. The bearings in a car wheel are subject to both thrust and radial loads.
BY SNEHAL PATEL
BEARING
CH.5 Maintanace of bearing :
Many bearings require periodic maintenance to prevent premature failure, although some such as fluid or magnetic bearings may require little maintenance. Most bearings in high cycle operations need periodic lubrication and cleaning, and may require adjustment to minimise the effects of wear. Bearing life is often much better when the bearing is kept clean and well-lubricated. well-lubricate d. However, many application applicationss make good maintenance difficult. For example bearings in the conveyor of a rock crusher are exposed continually to hard abrasive particles. Cleaning is of little use because cleaning is expensive, yet the bearing is contaminated again as soon as the conveyor resumes operation. Thus, a good maintenance program might lubricate the bearings frequently but clean them never.
BY SNEHAL PATEL
BEARING
CH. 6 Application of Bearing :1. Demonstration apparatus 2. Sliding door mechanism 3. Hand tools, agricultu agricultural ral machines 4. Auxiliary machines, conveyor, lift, in apower station 5. Electric motor and generator 6. Metal cutting machines, ventilating fan, gear box 7. Compressor, I.C. engine, turbine and pump 8. Merchant ship, stringer, aeroplane and space craft 9. Pulp and paper mill machinery 10.Textile 10. Textile mill machines 11. Power press 12.Printing 12. Printing machinery 13.Power 13. Power plant machinery 14.Automobile 14. Automobile engine, road wheel hubs 15.Automobile 15. Automobile gear box 16.Centre 16. Centre bearing and differential d ifferential unrts 17.Construction 17. Construction machines 18.Heavy 18. Heavy earth moving machineries 19.Marine 19. Marine engines and other application 20. Wind mill and wind turbine 21.Cranes 21. Cranes and hoisting application application 22. Scooter wheels and motorcar or truck wheels 23. Locomotive application 24.Cool running - Hybrid taperedroller-spindle taperedroller-spindle bearings help machine ma chine tools cut without cutting fluids. 25.Improve 25. Improve Turbomachinery Reliability By Taking Corrective Procedures 26. Bearing basics for gas-industry screw compressors 27.Helicopter 27. Helicopter application puts ceramic-coated spherical plain bearings through their paces
BY SNEHAL PATEL
BEARING
References : www.google.com www.Wikipedia.com www.scribd.com www.asme.com
Follow me on – Facebook
[email protected] Twitter Snehalpatel2909
BY SNEHAL PATEL
