WITH EFFECT FROM THE ACADEMIC YEAR 2010 - 2011
ME 251
KINEMATICS OF MACHINES
Instruction Lectures: 3 Periods per week
Drawing / Tutorials: 2 Periods per week
Duration of University Examination 3 Hours
University Examination 75 Marks
Sessional 25 Marks
UNIT-I:
Definition of link, element, pair, kinematic chain, mechanism and machine, Grubler’s criterion, single and double slider chains, inversions of quadratic cycle chain, inversions of single and double slider crank chains. Fundamentals of coupler curves, Robert’s law, mechanism with lower pairs and straight line motion mechanism, Pantograph, Peaucerlier, Hart, Davis and Ackerman’s Steering gear mechanisms.
UNIT-II
Analysis of mechanisms: Graphical methods to find velocities of mechanisms, instantaneous centre, body centre and space centre, Kennedy’s theorem, Graphical determination of acceleration of different mechanisms including Coriolis component of acceleration. Analytical method to find the velocity and acceleration, analysis of four bar mechanism with turning parts, Freudenstein’s method for four bar linkage synthesis.
UNIT-III
Laws of Friction: Friction in screw threads, pivots, collars and clutches, friction axis of link and friction circle.
Belts and Ropes: Open and closed belt drives, length of belt, ratio of tensions, effect of centrifugal tension and initial tension over power transmission, condition for maximum power.
Brakes and Dynamometers: Block or shoe, band and block, internal expanding shoe brake, Prony, Rope brake, belt transmission, Torsion dynamometers.
UNIT-IV
Cams: Types of cams and followers, Displacement diagrams for followers, uniform motion, parabolic motion, simple harmonic motion, cycloidal motion. Drawing cam profile with knife-edge follower, translating roller follower and translating Flat follower, cams of specified contour: Eccentric circle cam with translating flat power, Eccentric circle cam with translating roller follower.
UNIT-V
Gears: Classification of gears, Spur gears – Nomenclature, law of gear tooth action, involute as gear tooth profile, interference of involute gears, minimum number of teeth to avoid interference, contact ratio, cycloidal tooth profile, comparison of involute and cycloidal tooth profile.
Helical gears: Helical gear tooth relations, contact of helical gear teeth, Gear trains – Simple and compound, reverted and depicyclic gear trains.
Suggested Readings:
- S.S. Ratan, Theory of Machines, Tata McGraw-Hill Publications, 2005.
- J.E. Shigley, Theories of Machines, McGraw – Hill Publications, 2005.
- Thomas Bevan, Theory of Machines, CBS Publishers, 2005.