KINEMATICS OF MACHINES-UNIT-I-BASIC CONCEPTS & INTRODUCTION

BASIC CONCEPTS OF KOM

1. KINEMATICS OF MACHINES
UNIT-1
BASIC MECHANISM

2. Kinematics
•Kinematicsisthebranchofclassical
mechanicswhichdescribesthemotionof
points,bodies(objects)andsystemsofbodies
(groupsofobjects)withoutconsiderationof
thecausesofmotion.

3. Kinematics of machines
•Deals with study of relative motion between
the various parts of the machines(without
considering forces)
•The kinematics is a study of geometry of
motion ( displacement, velocity, acceleration
of machine part)

4. MECHANISM
Mechanism–Partofamachine,which
transmitmotionandpowerfrominputpointto
outputpoint

5. Example for Mechanism
Courtesy:www.technologystudent.com

6. Example for Mechanism

7. MACHINE

8. RESISTANT BODY

9. LINK or ELEMENT

10. EXAMPLES FOR LINK

11. TYPES OF LINK

12. RIGID LINK

13. FLEXIBLE LINK

14. FLUID LINK

15. STRUCTURE

16. MACHINE Vs STRUCTURE

17. KINEMATIC PAIR

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

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

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

21. 3. Based on Type of constraint

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

23. LOWER PAIR

24. HIGHER PAIR

25. DEPEND ON RELATIVE MOTION
INKINEMATIC PAIRS

26. ii) Turning pair

27. iii) Rolling pair

28. iv) Screw pair (helical pair)

29. v) Spherical pair

30. DEPEND ON CONSTRAINING MOTIONS
INKINEMATIC PAIR

31. TYPES OF CONSTRAINED
MOTIONS

32. 1. COMPLETELY CONSTRAINED MOTION

33. 2.INCOMPLETELY CONSTRAINED MOTION

34. 3.SUCCESSFULLY CONSTRAINED MOTION

35. KINEMATIC CHAIN

36. HOW TO FIND
KINEMATIC CHAIN ORNOT

37. EXAMPLE .1
ARRANGEMENT OF THREE LINKS

38. SOLUTION

39. EXAMPLE-2
ARRANGEMENT OF FOUR LINKS

40. EXAMPLE –3
ARRANGEMENT OF FIVE LINKS

41. JOINTS

42. 1.Binary joint

43. Checkingwhether it’s a kinematic chain

44. 2.Ternary joint

45. 3.Quaternary Joint

46. DEGREES OF FREEDOM (DOF):
Itisthenumberofindependentcoordinatesrequiredto
describethepositionofabody.

47. 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.

48. (a)Sidingpair[DOF=1]
(b)Turningpair(revolutepair)[DOF=1]

49. (c)Cylindricalpair[DOF=2]
(d)Rollingpair[DOF=1]

50. .
(e)Sphericalpair[DOF=3]
Eg.Ballandsocketjoint
(f)Helicalpairorscrewpair[DOF=1]

51. PROBLEMS

52. DOF(F)=3(n-1)-2j-h
or
F=3(n-1)-2l-h
n=number of links
j=number of binary joint
l= number of lower pair
h= number of higher pair

53. FIND THE DEGREE OF FREEDOM(MOBILITY) FOR
THE GIVEN DIAGRAMS

54. •n=5
•h=0
•J=binary joint+ (2*ternary joint)+(3* quaternary
joint)
•B.j=(2,3)(1,4)=2
•T.j=(1,2,5)(4,5,3)=2
•J=2+(2*2)+0=6
•F=3(n-1)-2j-h
•F=3(5-1)-2(6)-0
•F=12-12=0(structure)

55. EXAMPLE-1

56. EXAMPLE-2
•n=6
•h=0
•J=binary joint+ (2*ternary
joint)+(3* quaternary joint)
•B.j=(1,2)(3,4)(4,5)(1,6)(2,3)
(5,6)(1,4)=7
•DOF=3(n-1)-2j-h
•DOF=3(6-1)-2(7)-0=1
•DOF=1(one input motion is
required)

57. EXAMPLE -3
•n=7
•h=0
•J=binary joint+ (2*ternary joint)+(3*
quaternary joint)
•B.j=(1,2)(2,3)(3,4)(4,5)(5,6)(6,7)(7,1)
(3,6)=8
•DOF=3(n-1)-2j-h
•DOF=3(7-1)-2(8)-0=2
•DOF=2(two input motion is required)

58. EXAMPLE-4
•n=4
•h=(1,4)=1
•Lower pair=
(1,2)(2,3)(3,4)=3
•DOF= 3(n-1)-2l-h
•DOF=3(4-1)-2(3)-1=2
•DOF=2(Two input
motion is required)

59. EXAMPLE -5
•n=3
•h=(3,2)=1
•Lower pair=(1,3)(1,2)=2
•DOF= 3(n-1)-2l-h
•DOF=3(3-1)-2(2)-1=1
•DOF=1(one input motion
is required)

60. •n=6
•h=0
•J=binary joint+ (2*ternary
joint)+(3* quaternary joint)
•B.j=(6,1)(1,2)(3,6)(4,5)(5,6)=5
•T.j=(2,3,4)=1
•J=5+2*1=7
•DOF= 3(n-1)-2j-h
•DOF=3(6-1)-2(7)-0=1
•DOF=1(one input motion is
required)

61. 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

62. INVERSIONS OF FOUR BAR
CHAIN

63. FIRST INVERSION -

65. SECOND INVERSION

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

67. THIRD INVERSION

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

69. PANTOGRAPH
-USED TO ENLARGE THE SMALL GIVEN DIAGRAM

70. WORKING ---PANTOGRAPH

71. "Pantograph" is a drawing instrument to magnify figures.
Tracing the original figure by moving the red point,we can automatically
obtain the magnified figure with the pen at the blue point. Find the ratio of
magnification when the lengths of the arms are defined in the right figure.

72. ACKERMAN STEERING

73. INVERSIONS OF SINGLE SLIDER
CRANK CHAIN

74. First Inversion

75. Second Inversion

76. .

77. .

78. Third Inversion

79. .

80. .

81. Fourth Inversion

82. Pendulam pump or Bull Engine

83. Hand Pump

84. INVERSIONS OF DOUBLE SLIDER
CRANK CHAIN

85. ,

86. Second Inversion

87. Third Inversion

88. .

89. .

90. Toggle mechanism,
UNIT -I

92. toggle mechanisms
•Thetoggle mechanismscan be used in the
situation when one needs to output large
force subject to a short stroke, for example,
the stone crushers and mechanical presses,
etc. The shown mechanism has a toggle
position when the two lower links arrange to
be aligned. At this position, the slider can
produce an extremely large power to press
workpiece.

94. .
.

95. Intermittent motion mechanisms
Ratchet and pawl mechanism

96. Application of Ratchet Pawl
mechanism

97. ,
.

98. .
.

99. Intermittent motion mechanisms
Geneva wheel mechanism

100. Straight line generators
Unit -1

101. Scott Russell straight line Mechanism

102. Arrangement
•The green link is 2 times greater than the
length of blue link. This blue link is pinned as
shown in fig with green link.
•One more requirement is that the slider's
connection pin needs to be sliding in a line
that would intersect the static pivot end of the
short link.

103. Peaucellier Exact Straight Line Mechanism
•Peaucellier linkage can convert an input circular
motion to the exact straight line motion.
•Theconstructionofthismechanismissuchthat
thepointwhichisconnectedtothecrankmoves
inacircularpathandthepointtraversingthe
straightlineisselectedastheoutputpoint.
•Thelinkagehasarhombicloopformedofthe
equallengthmembers,5,6,7and8.Twoequal
lengthlinksareconnectedtotheopposite
cornersoftherhombusatoneendandtoa
commonfixedpointO4attheotherends.
•The point A of the rhombus is connect to fixed
point O2 through the link 2. The length of the
link 2 is equal to the distance between points
O2 and O4.
•By the constraints of the geometry point A moves
in a circular path and as the point A moves in a
circle point P traverses an exact straight line path
normal to the line joining O2 and O4.

104. Peaucellier Apparatus
•---For drawing straight lines

105. .
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.

106. Some important concepts in link
mechanisms are:
•Crank:A side link which revolves relative to the frame is called a crank.
•Rocker: Any link which does not revolve is called a rocker.
•Crank-rocker mechanism:In a four bar linkage, if the shorter side link
revolves and the other one rocks (i.e., oscillates), it is called a crank-rocker
mechanism.
•Double-crank mechanism: In a four bar linkage, if both of the side links
revolve, it is called a double-crank mechanism.
•Double-rocker mechanism: In a four bar linkage, if both of the side links
rock, it is called a double-rocker mechanism.

107. 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

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

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

110. Effect of Transmission angle on
mechanical advantage