1. BASIC MECHANICAL ENGINEERING
FIRST YEAR ENGINEERING (University of Pune)
Prepared By- Prof. S.S. Khasbage
BASIC MECHANICAL ENGINEERING
Prof. S.S.Khasbage

2. Introduction to Mechanical Engineering
UNIT I
Mechanical Elements: Function, Sketch, Description, Uses and Classification of – Shaft, Axle, Parallel Key, Rigid Flange Coupling, Ball Bearing, Single Plate Clutch & Disc Brake
Power Transmission Devices: Construction, Working, Comparison , Application and Classification of – Belt Drives (Flat & V-Belt), Chain Drives and Spur Gear Drive arranged with Simple Gear Train
Introduction to Mechanical Engineering
Book Referred – Design of Machine Elements by V. B. Bhandari
Prof. S.S.Khasbage

3. Text & Reference Books
Basic Mechanical Engineering by G. Shanmugam & S. Ravindran, Tata McGraw-Hill Publisher
Foundation of Mechanical Engineering by R. K. Purohit, Scientific Publisher
Elements of Mechanical Engineering by C. S. Chetankumar & B. P. Mahesh, S. Chand Publications
Engineering Thermodynamics by P. K. Nag, Tata McGraw-Hill Publisher (Unit No. V & VI)
Elements of Workshop Technology by Chaudhari & Hajra, Media Promoters & Publishers (Unit No. III & IV)
Prof. S.S.Khasbage

4. Marking Scheme 50+50+25 Online Test: 50 Marks
Online Test 1: 30 Minutes Examination, 25 Marks
Online Test 2: 30 Minutes Examination, 25 Marks
Theory Paper: 2 Hours Examination, 50 Marks
Term-work: 25 marks
Prof. S.S.Khasbage

5. Objective and Outcomes of Unit I
Understand and identify basic machine elements and power transmission devices with their functions.
Outcomes of Unit I:
Distinguish between different Basic Machine Elements with their application
Enable to decide a correct system or device required in a specific application
Knowledge of advantages and limitations of selected system or device over other options
Prof. S.S.Khasbage

6. Mechanical Machine Elements
Holding Type
Nuts and Bolts
Keys
Couplings
Rivets
Cotters
Supporting Type
Body Frame
Axle
Bearings
Frames
Power Transmitting Elements
Gears Shafts Pulleys and Belts Sprockets and Chains Clutches
Prof. S.S.Khasbage

7. Automobile Transmission System
Prof. S.S.Khasbage

8. Shaft
The shaft is a rotating bar generally of circular cross section, which is used to transmit torque or rotational motion.
Common Terms Associated with Shafts:
Transmission Shaft
Line Shaft
Counter Shaft
Jackshaft
Spindle
Crankshaft
Prof. S.S.Khasbage

9. Transmission Shaft
The shaft which is directly connected power is called transmission shaft
Prof. S.S.Khasbage

10. Line Shaft
Line shaft is a very long transmission shaft which is directly driven by the prime mover (or power source) and which is used distribute power from main the main power source to different power consuming devices.
Prof. S.S.Khasbage

11. Counter Shaft
Counter shaft is a secondary shaft which is not directly connected to power source but driven by it through belt, chain or gear drive.
Prof. S.S.Khasbage

12. Crankshaft
The shaft which used in multi cylinder IC engine to which cranks are embedded is called crankshaft.
Prof. S.S.Khasbage

13. Spindle
Spindle is peculiar terminology associated with shafts of machine tools which provide rotary motion either to a cutting tool or to a work piece. .
Prof. S.S.Khasbage

14. Jackshaft
A short intermediate shaft on which two pulleys or gears or sprockets are mounted to change the speed within the transmission system.
Prof. S.S.Khasbage

15. AXLE
The axle is a non rotating bar which doesn’t transmit any torque but only used to supports rotating machine elements like wheels, pulleys etc.
Wikipedia.com
 BFF Design Ltd
Prof. S.S.Khasbage

16. Difference between Axle and Shaft
Axle is a non rotating member
Shaft is rotating member
Primary function is to provide support to elements like wheel, pulley etc.
Primary function is to transmit torque.
Axle is primarily subjected to bending (axial force)
Shaft is subjected to bending, torque, as well as vibrations
Design of axle is relatively simple compared to shaft
Design of shaft is complex as compared axle because shaft is simultaneously subjected to torque, bending, and vibrations
Depending upon loading condition, cross sectional area of axle can be different e. g. Rectangular, Circular, I-section, T-section etc.
Cross sectional area of shaft is generally circular because it causes minimum vibrations and stress as compared to other shapes of same cross sectional area.
e.g. Axles of automobiles, railway buggies.
e.g. Shaft of electric motor, shaft of IC engine
Prof. S.S.Khasbage

17. Mechanical Keys
The key is machine element which is used on shaft to position/secure the rotating elements like gears, pulleys or sprockets and prevent free relative rotation between shaft and the element which is mounted on the shaft
Key transmits the torque from
the shaft to the rotating element or
vice-versa.
Prevent the relative motion between
shaft & hub
Prof. S.S.Khasbage

18. Classification of Keys:
Saddle
Sunk Keys
Splines
Tangent keys
Kennedy Keys
Round keys and taper Pins
Prof. S.S.Khasbage

19. Sunk Keys Rectangular Square Parallel Gibb Headed woodruff Feather Key
W=D/4
H=2/3 W
W=H=D/4
Prof. S.S.Khasbage

20. Tangent Keys
The tangent key transmits the torque only in one direction by means of compressive force alone
Tangent key is subjected to compressive stress
Two tangent keys separated by 900 angle force hub and shaft to concentric position
Example: Kennedy Key
Prof. S.S.Khasbage

21. Saddle Key
The saddle key is a key which fits in key way of hub only and transmits torque between hub and shaft by means of friction
Saddle key doesn’t sink inside the shaft hence it is NOT a sunk key
Saddle keys have low torque transmitting capacity
As key way on shaft is avoided saddle keys don’t weaken the shaft
Prof. S.S.Khasbage

22. Sunk Key
The sunk key is a key in which some portion of its thickness fits in keyway on shaft and remaining portion of the thickness sits in key way of hub.
The torque is transmitted by means of shear force within the key.
As key way on shaft is required sunk keys weaken the shaft
Prof. S.S.Khasbage

23. Why Tapered Keys ?
The thickness of the tapered key changes along the length
As compared to parallel keys, the tapered keys are more tight because of wedge action
Tapered keys are easy to remove as compared parallel keys
Prof. S.S.Khasbage

24. Parallel Key
The parallel keys have uniform thickness along their length
Prof. S.S.Khasbage
Technifast.com

25. Gib Headed Keys
The key which is provided with head for easy removal is called Gib headed key
Prof. S.S.Khasbage

26. Woodruff Key
The Woodruff key is sunk key, almost in the form of semicircular disc of uniform thickness
The curved portion of key sits inside slot made on shaft whereas flat portion sits inside slot made on hub
The extra depth of Woodruff key prevents its tendency of slip over during heavy load condition.
The Woodruff key is extensively used in tapered shafts because it can align easily with the hub slot by slight rotations
Woodruff keys weaken the shaft because of their extra depth th
Prof. S.S.Khasbage

27. Feather Key
The feather key is a key which allows relative axial motion between hub and shaft but prevents relative rotational motion between them
The key is permanently fixed to the shaft generally.
Clearance is provided between hub and key so that hub slides freely over the key
Sometimes double Gib headed key is provided so that hub will not come out completely
Prof. S.S.Khasbage

28. Couplings
Coupling is the mechanical element used to connect two shafts permanently of a transmission system and transmit the torque from one shaft to another.
Functions of Coupling :
Connects two shafts
Introduces mechanical flexibility and tolerates small misalignment (Valid for Flexible Couplings)
Adds stiffness to the system hence reduces bending
Reduces the transmission of vibrations and shocks (Valid for some of Flexible Couplings)
Prof. S.S.Khasbage

29. Universal/ Hooke’s Joint
Couplings
Rigid
Sleeve or Muff
Split Muff
Flange
Un-Protected type
Protected type
Flexible
Bush pin type
Universal/ Hooke’s Joint
Oldham
Beam coupling
Prof. S.S.Khasbage

30. Rigid Couplings
These couplings are not capable of tolerating any misalignment between two shafts.
These couplings are not capable of absorbing shocks and vibrations.
These are simple and inexpensive.
Prof. S.S.Khasbage

31. Muff Coupling
Prof. S.S.Khasbage
youtube.com

32. Split Muff Coupling youtube.com
Prof. S.S.Khasbage
youtube.com

33. Unprotected Rigid Flange Coupling
Prof. S.S.Khasbage
youtube.com

34. Un – protected Flange Coupling grabcad.com
Prof. S.S.Khasbage

35. Protected Rigid Flange Coupling
Prof. S.S.Khasbage
youtube.com

36. engineeringdesigns.blogspot.in
Prof. S.S.Khasbage

37. Flexible Couplings
Flexible couplings allow axial and/or angular misalignment between two shafts
Universal Coupling
Beam Coupling
wikipedia.org
Oldham Coupling
cornell.edu
Prof. S.S.Khasbage

38. Bush Pin Coupling Brass or Brass Coated with Rubber Bush is used .
Application- Very small axial misalignments
e.g. Coupling between electric motor and pump
Prof. S.S.Khasbage

39. Oldham’s Coupling
Allows small axial misalignment between the two shafts
Prof. S.S.Khasbage

40. Beam/Helical Coupling
Allows angular misalignment between the two shafts
Prof. S.S.Khasbage
youtube.com

41. Hooke’s Joint /Universal Coupling
Prof. S.S.Khasbage

42. Bearings
Bearing is a device that allows relative motion between two parts, such as shaft and housing with low friction as well as it restricts the motion of shaft in one desired direction only.
Functions:
It ensures free rotation of the shaft or the axle with minimum friction.
It supports shaft or axle and holds it in the correct position.
It takes the forces acting on the shaft or the axle in both working as well rest condition and transfers them to frame on which it is mounted.
Prof. S.S.Khasbage

43. Prof. S.S.Khasbage surajkhasbage@ymail.com

44. Bearings Rolling Contact Ball Bearing Roller Bearing Sliding Contact
Hydrostatic Bearing
Hydrodynamic
Bearing
1.Cylindrical Roller
Bearing.
2.Needle Roller Bearing.
3. Tapered Roller Bearing
4.Tapered Roller Thrust Bearing
eg. Journal Bearing (Bush Bearing)
1.Single row deep groove Ball
Bearing.
2.Doublerow deep groove Ball Bearing.
3.Angular Contact Ball Bearing
4.Thrust Ball Bearing
Prof. S.S.Khasbage

45. Ball Bearings
The purpose to support a load while permitting relative motion between two elements of a machine.
The components of a typical rolling contact bearing are the inner race, the outer race, cage and the rolling elements.
SHAFT
Prof. S.S.Khasbage
yourdictionary.com

46. Angular Contact Ball Bearing
Double Row Deep Groove Ball Bearing
Single Row Deep Groove Ball Bearing
Prof. S.S.Khasbage
Thrust Ball Bearing

47. Roller Bearings Cylindrical Roller Bearing Tapered Roller Bearing
Needle Roller Bearing
Prof. S.S.Khasbage
Tapered Roller Thrust Bearing

48. Journal Bearings Hydrostatic Bearing: Oil is Pressurized
Hydrodynamic Bearing: Oil is NOT Pressurized
Prof. S.S.Khasbage

49. Clutch
It connects or disconnects the source of power from the remaining parts of the power transmission system at the will of the operator.
Clutches
Positive Clutch
Claw or Jaw type
Friction Clutch
Plate or Disc
Single Plate
Multiple Plate
Cone
Centrifugal
1.The force requires to disengage should be minimum, 2.operation of engagement & Dis engagement can be done at any speed
3.Heat generation during engagement should be minimum 4.there should not be more stress generation in clutch material
Prof. S.S.Khasbage

50. Positive Type Clutch hellotrade.com
Adv-1. no heat 2. no slip 3. less maintenance
Dis-cannot engage at high speed , engagement at any speed is with shock and noice.
hellotrade.com
Prof. S.S.Khasbage

51. Single Plate Clutch codecogs.com
Prof. S.S.Khasbage
codecogs.com

52. Centrifugal Clutch Multi- plate Clutch Cone Clutch
Prof. S.S.Khasbage

53. Block Brake/Drum B rake
Brakes
Brake is a mechanical device used to stop or slow down the moving body.
Brakes
Mechanical
Block Brake/Drum B rake
External
Internal Expanding
Band Brake
Disc Brake
Electrical
Eddy Current Brakes
Prof. S.S.Khasbage

54. Disc Brake Assembly Absorbs more heat than a drum brake assembly
When the brake pedal is pushed, brake fluid from the master cylinder compresses the brake pads against the rotors attached to the vehicle's front wheels.
The friction between the stationary pads and the revolving rotors causes the rotors and wheel to slow down/ stop.
howstuffworks.com
Prof. S.S.Khasbage

55. Prof. S.S.Khasbage surajkhasbage@ymail.com

56. Internal Expanding Type
Single Block
Double block
External type
Internal Expanding Type
Prof. S.S.Khasbage

57. Difference Between Clutch and Brake
Function: Absorbs Power
During Normal Operation of Vehicle: Disengaged
Position of mating Surfaces: One surface is always stationary and other may be fixed or rotating
Final Condition : Both members are at rest and have no relative motion.
Clutch
Function: Transmits Power
During Normal Operation of Vehicle: Engaged
Position of mating Surfaces: One surface is always rotating and other may be fixed or rotating
Final Condition : Both members rotate at the same speed and have no relative motion.
Prof. S.S.Khasbage

58. Drives Drive is a link between Prime mover and Driven machinery.
Prime movers, power producing devices.
Power Transmitting link
Driven Machinery, Power absorbing devices
Flour Mill
Oil Mill.
Vehicle propulsion.
Machine Tools.
Compressors, pumps.
Material handling Equipments.
House hold gadgets.
I.C. Engines
Steam Engines.
Gas Turbines.
Steam Turbines.
Water Turbines.
Wind Mills.
Electric Motors.
Chain drive.
Belt Drive.
Rope Drive.
Gear Drive.
Prof. S.S.Khasbage

59. Flat Belt Drive Large distance between shafts
cheaper compared to ‘V’ belts.
The slip is more.
Cross belts are used to reverse direction of rotation.
Flat belts provide only small speed ratios.
Cross section
Prof. S.S.Khasbage
wikipedia.com

60. Quarter Turn Belt Drive
chestofbooks.com
Open Belt Drive
Quarter Turn Belt Drive
mikrobot.blogspot.in
Prof. S.S.Khasbage

61. Cross Belt Drive Cross Belt Drive
chestofbooks.com
Cross Belt Drive
Increased angle of contact results in increased grip
However, rubbing of belt causes reduced belt life
Prof. S.S.Khasbage

62. V Belt Drive
Prof. S.S.Khasbage
wikipedia.com

63. Chain Drive
Prof. S.S.Khasbage
wikipedia.com

64. Chain Elements Inner Link Bushing Pin Outer Link wikipedia.com Roller
Prof. S.S.Khasbage
patentpending.blogs.com

65. Chain Elements
Inner Link: It has bigger hole diameter
Outer Link: It has smaller hole diameter
Bush : It is a hollow cylinder and it press fits inside two inner links
Pin: It passes through the bush, two outer links are press fitted on it
Roller: It is a hollow cylinder which can rotate freely over bush
Bush and pin joint is responsible for flexibility of the chain.
Roller is added to reduce the wear of the sprocket
Prof. S.S.Khasbage

66. Chain Drive Advantages Disadvantages No slip
High transmission efficiency (upto 98 percent)
High power transmission capacity
High speed ratio (8 to 10 in one step)
It gives less load on the shafts because pretension is not required
It can be operated under adverse temperature and atmospheric conditions.
Disadvantages
High cost
At high speed noise increases
Requires lubrication and frequent maintenance
Prof. S.S.Khasbage

67. Belt Drive Advantages (Over Chain Drive)
High Operating Speed
Allows angular misalignment between two shaft
Need not to have exact centre distance between two shafts
Low Cost, Easy installation
Disadvantages (Over Chain Drive)
Slip causes fluctuation in speed
Low power transmission Capacity
Low speed Ratio (upto 3)
Less Compact
Pretension of belts is required which increases load on the shaft
Prof. S.S.Khasbage

68. V Belt Drive Advantages (over Flate Belt Drive)
Less slip
Less noise because V belts are endless
The high velocity ratio (maximum 10) may be obtained.
High power transmitting capacity
More Compact
Disadvantages (over Flate Belt Drive)
The centrifugal force prevents the use of V-belts at high speeds
Cost is high
Prof. S.S.Khasbage

69. Classification of the Gears based upon position of shaft axes
Parallel Shaft
Spur
Helical
Rack & Pinion
Intersecting Shaft
Bevel
Non – parallel and non Intersecting
Spiral
Worm
Prof. S.S.Khasbage

70. Gears
Gear is a toothed wheel which is used in a power transmission system to transmit torque/power from one shaft to other
Spur Gears
Helical Gears
Bevel Gears
Worm Gear
Rack and Pinion
Prof. S.S.Khasbage

71. Gear is a tooth profile is either involute or cycloid.
Gear Terminology
Gear is a tooth profile is either involute or cycloid.
Prof. S.S.Khasbage

72. Spur Gear
Prof. S.S.Khasbage

73. Helical Gear Spur Gear wikipedia.com Rack and Pinion
Prof. S.S.Khasbage
Rack and Pinion

74. Bevel Gear
Prof. S.S.Khasbage
wikipedia.com

75. Worm Gear
Prof. S.S.Khasbage
wikipedia.com

76. Spur Gear Train with Idler gear
a) Simple Gear Train
Spur Gear Train with Idler gear
Output 3
Idler Gear
Prof. S.S.Khasbage

77. b)Coumpound Gear Train
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78. Gear Train c) Reverted Gear Train
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79. d) Epicyclic Gear Train
Prof. S.S.Khasbage

80. Features of Gear Drives
Positive drive
No slip results to constant velocity ratio
Compared to chain drives it is smoother in operation.
It is suitable when the centre distances are small.
for given amount of power transmission, the drive is most compact.
Precise ratios are possible.
Very long life.
Expensive
Compared to belt drives gear drives are Noisy.
Comparatively Expensive and Maintenance cost is also higher.
They require Precise Alignment of the shafts.
Prof. S.S.Khasbage

81. What is the brake? How does it differ from clutch? [ 2+ 2+4]
University Question:
YEAR 2010
What is the brake? How does it differ from clutch? [ ]
Explain with neat sketch ( 4 each)
Ball Bearing
Transmission Shaft
YEAR 2011
Q.7)
(B) Distinguish between Kinematic Pair and Kinematic Chain with
an example for each. [06]
(C) What are the advantages and disadvantages of Belt Drives ? [04] OR
Q.8) (A) What is a Clutch ? Explain with a neat diagram the working
of a Single Plate Clutch. [07]
(B) What is a Brake ? How brakes are classified [09]
Prof. S.S.Khasbage

82. (C) Compare Flat Belt and V-Belt. [06] OR Q.12)
YEAR 2009
Q.11) (A) Draw sketch of Single Plate Clutch and explain its working. [06]
(C) Compare Flat Belt and V-Belt. [06] OR
Q.12)
(C) State advantages and disadvantages of Chain Drive over Belt
Drive. [06]
YEAR 2012
7. A) Difference between ‘Line shaft’ and ‘Counter shaft’ with diagram. (2+2+4=8)
B) How the couplings are classified (2+3+3=8)
8. B) Define ‘Gear Ratio’ and explain with neat (2+3+3=8)
Prof. S.S.Khasbage

83. (B) Explain any one type of Clutch with sketch. [06] OR
YEAR 2010
Q.11)
(B) Explain any one type of Clutch with sketch. [06] OR
Q.12) (A) Compare Belt and Gear Drive. [06]
YEAR 2011
8. A) How gears are classified ? What are the functions of gears ? State applications
of different types of gears. (3+2+3)
Prof. S.S.Khasbage

84. Differentiate between Belt drives and Gear drives.
Practice Question
State the advantages and disadvantages of V belt over Flat bet drive.
Differentiate between Belt drives and Gear drives.
Compare merits and demerits of Individual drive with group drive.
Suggest suitable element for following. Shaft at right angles, Shafts with slight misalignment, Two parallel shafts 3-4 m apart, Two parallel shafts 10 cm apart.
Differentiate between flat belt and V belt. Show their cross-sections.
Suggest a suitable element for the following, Non parallel non intersecting shafts, Intersecting shafts, Parallel shafts with slight misalignment, Shafts 2-4 m apart.
What is a chain drive? How chains are classified?
Draw sketches of Helical gears, Bevel gears, Worm and Worm wheel.
Differentiate between Belt drive and Chain drive.
Prof. S.S.Khasbage

85. Appendix
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86. Rivets
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87. Cotter Joint
Prof. S.S.Khasbage