BASICS OF MECHANISMS Basic Mechanisms and its terminologies – Degree of freedom – Mobility – Kutzbach criterion – Grubler’s criterion for Planar Mechanisms – Grashof’s law – Kinematic inversions of Four bar chain – Single slider – Double slider Crank Chains – Quick Return Mechanisms – Mechanical advantage – Classification of Mechanisms.

1. KINEMATICS OF MACHINES
UNIT-1
BASICS OF MECHANISMS

2. Differences
• Kinematics describes the motion of the bodies
and deals with finding out velocities or
accelerations for various objects.
• Kinetics explains how a body responds when a
force or torque is applied to it.
• Dynamics deals forces and their effects while
acting upon machine parts in motion
• Statics deals forces and their effects while the
machine parts at rest.

3. MACHINE

4. RESISTANT BODY

5. LINK or ELEMENT

6. EXAMPLES FOR LINK

7. TYPES OF LINK

8. RIGID LINK

9. FLEXIBLE LINK

10. FLUID LINK

11. STRUCTURE

12. MACHINE Vs STRUCTURE

13. KINEMATIC PAIR

14. CLASSIFICATION OF KINEMATIC PAIRS
• Based on type of Contact
• Based on type of Relative motion
• Based on type of constraint

15. 1. Based on Nature of contact
or
Type of contact

16. 2. Based on Nature of relative motion between them
or
Type of relative motion

17. 3. Based on Type of constraint

18. BASED ON NATURE OF CONTACT
IN KINEMATIC PAIRS
• LOWER PAIR
• HIGHER PAIR

19. LOWER PAIR

20. HIGHER PAIR

21. DEPEND ON RELATIVE MOTION
IN KINEMATIC PAIRS

22. ii) Turning pair

23. iii) Rolling pair

24. iv) Screw pair (helical pair)

25. v) Spherical pair

26. DEPEND ON CONSTRAINING MOTIONS
IN KINEMATIC PAIR

27. TYPES OF CONSTRAINED
MOTIONS

28. 1. COMPLETELY CONSTRAINED MOTION

29. 2.INCOMPLETELY CONSTRAINED MOTION

30. 3.SUCCESSFULLY CONSTRAINED MOTION

31. KINEMATIC CHAIN

32. HOW TO FIND
KINEMATIC CHAIN OR NOT

33. EXAMPLE .1
ARRANGEMENT OF THREE LINKS

34. SOLUTION

35. JOINTS

36. 1.Binary joint
Here,
Number of Links = 4
Number of Binary Joints = 4
If two links are connected at the
same joint, it is called a Binary Joint

37. Checking whether it’s a kinematic chain

38. 2.Ternary joint
If three links are connected at the
same joint, it is called a ternary joint.
For the given Diagram, Apply Kline’s Criterion,
Number of Joints , j = Number of binary joints + 2 ( Number of
Ternary Joints)
= 3 + ( 2 x 2)
= 7

39. 3.Quaternary Joint
Number of Joints ,
j = Number of binary joints + 2 ( Number of Ternary joints) + 3 ( Quaternary
Joints)

40. DEGREES OF FREEDOM (DOF):
It is the number of inputs (number
of independent coordinates)
required to describe the
configuration or position of all the
links of the mechanism, with respect
to the fixed link at any given instant.
Degrees of freedom / mobility of a mechanism:

41. DEGREE OF FREEDOM OR MOBILITY
Degree of Freedom for plane Mechanism m (mobility):
It is defined as the no of input motions, which must be
independently controlled in order to bring mechanism into
useful engineering purpose.

42. Grueblers criteria – Constrained motion
F = 3(n-1) - 2l - h
Where, F = Degrees of freedom
n = Number of links = n2 + n3 +……+nj,
where, n2 = number of binary links,
n3 = number of ternary links…etc.
l = Number of lower pairs,
which is obtained by counting the number of joints. If
more than two links are joined together at any point,
then, one additional lower pair is to be considered for
every additional link.
h = Number of higher pairs

45. kutzbach criterion
n=3(l−1)−2j−h
Where
l= no. of links
j=no. of binary joints
This equation is called kutzbach criterion for
determining the number of degrees of
freedom of movability (n) of a plane
mechanism.

46. INVERSION MECHANISM
• Inversion of a kinematic linkage or mechanism is observing the
motion of the members of the mechanism with fixing different
links as reference frame. Each time when a different link is
chose as the frame link the mechanism shows different
characteristics of the motion.
• KEEPING ANY ONE OF THE LINK FIXED AND
ROTATING OR OSCILLATING OTHER LINKS-
THIS RESULTS DIFFERENT FORM OF MOTION OUTPUT FOR
DIFFERENT USAGE

47. Inversion of Mechanisms

48. Types of kinematic chain

49. .
How to use
• Drag the red point.
• The red point moves on a line when "Line"
option is selected.
• The red point moves on a circle when "Circle"
option is selected.

50. INVERSIONS OF FOUR BAR
CHAIN

51. INVERSIONS OF FOUR BAR
CHAIN

52. INVERSIONS OF FOUR BAR
CHAIN

53. INVERSIONS OF FOUR BAR
CHAIN

54. INVERSIONS OF FOUR BAR
CHAIN

55. FIRST INVERSION -

57. SECOND INVERSION

58. COUPLING ROD OF A LOCOMOTIVE – USED TO
TRANSMIT ROTATION FROM ONE WHEEL TO ANOTHER WHEEL
EXAMPLE --- IN TRAIN
• .

59. THIRD INVERSION

60. WATT INDICATOR MECHANISM- USED TO SHOW THE
STEAM PRESSURE IN THE CYLINDER

61. WORKING --- PANTOGRAPH

62. ACKERMAN STEERING

63. INVERSIONS OF SINGLE SLIDER
CRANK CHAIN

64. First Inversion

65. Second Inversion

66. .

67. .

68. Third Inversion

69. .

70. .

71. Fourth Inversion

72. Pendulam pump or Bull Engine

73. Hand Pump

74. INVERSIONS OF DOUBLE SLIDER
CRANK CHAIN

75. ,

76. Second Inversion

77. Third Inversion

78. .

79. .

80. .
.

81. .
.

82. Snap Action Mechanism
.

83. Motion Adjustment Mechanism
• Its used to adjust the motion of the link

84. Hooke’s joint

85. Scott Russell straight line Mechanism

86. Peaucellier Exact Straight Line Mechanism

87. Limit Position
It’s the position of mechanism in which the interior angle
between the coupler and crank link is either 180o or 360o

88. MECHANICAL ADVANTAGE OF
MECHANISM
-------- a quality measure
• Due to more usage of 4 bar mechanism, its necessary to study
some of the advantages of mechanisms.
• Which tell whether the mechanism is good one or not.
• It’s a quality measure of all mechanism

89. MECHANICAL ADVANTAGE
• It’s the ratio of output torque to the input torque
• M.A(ideal) =
• M.A (Actual) =
TA = Driving link torque
TB = Driven link Torque
A
B
A
B
T
T



 
A
B
A
B
T
T




90. Transmission Angle
• The angle between
Coupler and the follower
