|Antifriction bearing - Problems, Numericals & mini projects on Machine Design|
|By Prof S S Chauhan, IEC College of Engineering & Technology, Greater Noida|
Unit-3 Antifriction bearing
Objective: Student should have knowledge about different type of bearings its engineering applications and methods of designing of Ball and roller bearings from design charts
Theory and Numerical Problems
1. What is a bearing?
2. How will you classify the bearings?
3. On what factors does the selection of a bearing for a particular application depend?
4. Describe the various stages of friction in the case of plain bearings.
5. Differentiate between ‘Hydrodynamic’, ‘Wedge film lubrication’ and ‘Squeeze film lubrication’.
6. Distinguish between ‘Hydrodynamic bearings’ and ‘Hydrostatic bearings’.
7. What are the factors to be considered while selecting the material for plain bearing?
8. Name various bearing metals.
9. What is the function of lubrication in bearings?
10. Give the advantages and disadvantages of oils and greases.
11. Describe the various lubrication devices.
12. What s the importance of oils grooves in bearings?
13. Define ‘Bearing modulus’.
14. Define ‘Sommerfeld number’.
15. What is meant by ‘Self contained bearings’?
16. Give the applications and limitations of sliding bearings.
17. Enumerate the advantages and disadvantages of rolling contact bearings.
18. How will you classify the rolling contact bearings?
19. What are four main parts of a ball bearing?
20. Compare ball and roller bearings.
21 How are the rolling contact bearings manufactured?
22 What bearings are called ‘Needle bearings’? Give their applications.
23 What is the primary characteristic difference between a deep groove ball bearing and angular contact bearing?
24 here do we prefer to use taper roller bearing?
25 What is antifriction bearings. Discuss the materials that are used for manufacturing of bearings.
26 Explain rating life and basic load rating.
27 Where do we use thrust bearing? Explain the basis for bearing failure.
28 What is approximate friction power loss in a single radial ball bearing having a bore diameter of 55mm and subjected to a radial load of 225KN? The shaft rotates at 600RPM.
29 Determine the approximate friction torque expected in single deep groove ball bearing under a radial load of 30KN. The bore of the bearing is 50mm.
30 A bearing has a specific dynamic radial capacity of 24.5KN. What radial load the bearing can carry at 1200RPM if the desired life is 2000hours (for 90% group of bearing).
31 A radial load of 5Kn acts for 5 revolutions and reduces to 4.5Kn for 10 revolutions . The load variations then repeat itself. What is the mean cubic load?
32 Determine the 6200 series bearing which will be suitable for a radial load of 1.8Kn with the operation at 1200RPM for 2000hours. Loading is steady. Basic load capacity of various series can be see from DDB.
33 A 300 mm bore (dimension series 02) single row angular contact ball bearing has a 30 degree contact angle. If the bearing carries a 3.5 KN radial load and a 6 KN thrust load and the inner ring rotates at 1500 RPM, Determine the rating life in hours.
34 Mention the relative advantages of rolling bearings and sliding bearing. What do you understand by static capacity and dynamic capacity of ball bearing? Explain how you will determine the equivalent load on a bearing when simultaneously acting radial and thrust load are known.
35 A certain bearing is to carry a radial load of 5 at KN a speed of 10RPM of 20% of the time, a load of 30 KN at a speed of 60RPM for 50% of time and a load of 30 KN at 100RPM during 30% of the time with a desired life of 5,000 hours. No thrust load acts on bearing. What will be dynamic capacity of the bearing?
36 A shaft is subjected to the varying load cycle as follows; 3KN for 1 Sec, 1 KN for 1s and 0.5KN for 3s. If the shaft rotates at the constant speed of 500RPM, What basic load rating for each fraction of cycle should be used in selecting the ball bearing with a life of 15000 hours?
37 A 6203 single row deep groove ball bearing has a basic load rating of 4500 n and a basic dynamic capacity 7350N. What is the life expectancy (that 90% bearing reach or exceed) for a radial load of 1350N and a thrust load of 1260N? The outer ring is stationary.
38 Select bearing for a60m diameter shaft that rotates uniformly at 1800RPM. Due to bevel gear mounted on the shaft, the bearing will have to withstand a 5KN radial load and a 2KN thrust load. With any restriction of the type of a bearing select one that is satisfying for a rating life of 20,000 hours.
39 A single row deep groove ball bearing has a specific dynamic capacity of 46.3Kn(for 1000000 revolutions or 500hours at 33.3RPM , That90% of group of bearing will complete or exceed) if the speed of rotation is 1800RPM and the actual radial load applied to the bearing is 9 KN what is the life in revolutions
40 In the above problem how many hours of operation can be expected for the above?
41 What is the average life that can be expected in prob. 7
42 An SKF self aligning ball bearing no.1310 has a specific capacity 33.5KN (that is the rating of 33.5Kn such that 90% of group of bearing will last 500hours at 33.3RPM). If the equivalent radial load actually applied to the bearing is P=44.5KN determine the life in millions of revolutions expected (such that 90% of a group of bearing of same nos. will survive) the speed of rotation being 1800RPM. & the life in hours for 90% of the bearings.