Theory of Mechanisms and Machines

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2 Theory of Mechanisms and Machines

4 Theory of Mechanisms and Machines C.S. SHARMA Formerly Professor Department of Mechanical Engineering Jai Narain Vyas University Jodhpur KAMLESH PUROHIT Professor Department of Mechanical Engineering Jai Narain Vyas University Jodhpur New Delhi

5 THEORY OF MECHANISMS AND MACHINES C.S. Sharma and Kamlesh Purohit 2006 by PHI Learning Private Limited, New Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN The export rights of this book are vested solely with the publisher. Fourth Printing October, 2011 Published by Asoke K. Ghosh, PHI Learning Private Limited, M-97, Connaught Circus, New Delhi and Printed by Rajkamal Electric Press, Plot No. 2, Phase IV, HSIDC, Kundli , Sonepat, Haryana.

6 Chapter 15 Contents Preface... xiii Chapter 1 Introduction to Mechanisms and Machines Introduction Kinematic Link Kinematic Pairs Nature of Contact Nature of Relative Motion Nature of Mechanical Constraints Kinematic Chain Mechanism Four Bar Chain Inversions of Kinematic Chain Four Bar Chain Slider-crank Chain Double Slider-crank Chain Exercises Chapter 2 Kinematic Analysis of Mechanism Introduction Velocity Analysis Relative Velocity Method Slider-crank Mechanism Four Bar Mechanism Crank and Slotted Lever Mechanism Instantaneous Centre Method Arnold Kennedy Theorem Locating Instantaneous Centres Acceleration Analysis Procedure to Draw Acceleration Polygon of a Mechanism Klein s Construction v

7 vi Contents 2.7 Coriolis Acceleration Analytical Method Exercises Multiple Choice Questions Chapter 3 Synthesis of Mechanisms Introduction Number Synthesis Degree of Freedom of a Mechanism Grashof s Criterion of Movability Limit Positions, Dead Centres and Transmission Angle Dimensional Synthesis Synthesis by Relative Pole Method Synthesis of Four Bar Mechanism Synthesis of Slider-Crank Mechanism Synthesis of Mechanism by Inversion Method Synthesis of Four Bar Mechanism Synthesis of Slider-Crank Mechanism Slider-Crank Mechanism for Given Quick Return Ratio Synthesis of Mechanism by Analytical Method Freudenstein s Method of Synthesis Approximate Synthesis Using Least Square Technique Bloch s Method Exercises Multiple Choice Questions Chapter 4 Lower Pair Mechanisms Introduction Straight Line Motion Mechanism Exact Straight Line Motion Mechanism Approximate Straight Line Motion Mechanism Pantograph Engine Indicator Mechanisms Automobile Steering Mechanism Davis Steering Mechanism Ackermann Steering Mechanism Hooke s Joint Exercises Chapter 5 Friction Introduction Laws of Dry Friction

8 Contents vii 5.3 Angle of Friction Inclined Plane Friction Motion Up the Plane Motion Down the Plane Inclined Plane with Guide Friction Wedge Friction Screw Friction Pivot and Collar Friction Collar Bearings Pivot Bearing Friction Clutches Plate Clutches Cone Clutches Friction in Turning Pairs Friction Axis Exercises Multiple Choice Questions Chapter 6 Belts, Ropes and Chains Introduction Belt Drive Mechanics of Belt Drive Velocity Ratio Length of Belt Open-belt Drives Cross-belt Drives Ratio of Belt Tensions Ratio of Tensions in V-Belt Effect of Centrifugal Force Power Transmission Capacity Stresses in Belt Elastic Creep Belt Materials Stepped Pulley Drive Rope Drive Wire Rope Construction Forces on a Wire Rope Breaking Strength Chain Drive Types of Chain Chain Length Chordal Action Exercises Multiple Choice Questions

9 viii Contents Chapter 7 Brakes and Dynamometers Introduction Block Brakes Block Brakes with Small Angle of Contact Block Brake with Large Angle of Contact Band Brakes Simple Band Brake Differential Band Brake Band and Block Brake Internal Expanding Shoe Brake Effect of Braking on Vehicle Dynamometers Absorption Dynamometers Transmission Dynamometers Exercises Multiple Choice Questions Chapter 8 Governors Introduction Watt Governor Porter Governor Proell Governor Hartnell Governor Wilson-Hartnell Governor Spring-Controlled Gravity Governor Pickering Governor Characteristics of a Governor Effort of a Governor Power of a Governor Controlling Force Exercises Multiple Choice Questions Chapter 9 Cams Introduction Classification of Cams and Followers Cam Terminology Analysis of Follower Motions Constant Velocity Motion Simple Harmonic Motion Constant Acceleration and Deceleration Cycloidal Motion Polynomial Motion

10 Contents ix 9.5 Graphical Synthesis of Cam Profile Analytical Synthesis of Cam Profile Pressure Angle Cams with Specified Profile Tangent Cam with Roller Follower Circular Cam with Roller Follower Circular Cam with Flat Faced Follower Exercises Multiple Choice Questions Chapter 10 Gears Introduction Gear Terminology Law of Gearing Velocity of Sliding Forms of Gear Teeth Involute Profile Cycloidal Profile Arc of Contact Interference Minimum Number of Teeth to Avoid Interference Minimum Number of Teeth on Pinion with Rack Force Analysis of a Spur Gear Helical Gear Formative Number of Teeth Forces on Helical Gear Spiral Gear Efficiency of Spiral Gear Worm Gear Set Efficiency of Worm Gear Set Bevel Gears Exercises Multiple Choice Questions Chapter 11 Gear Train Introduction Simple Gear Train Compound Gear Train Epicyclic Gear Train Tabulation Method Relative Velocity Method Torque Transmitted by Epicyclic Gear Train Exercises Multiple Choice Questions

11 Theory Of Mechanisms And Machines 25% OFF Publisher : PHI Learning ISBN : Author : SHARMA, C. S., PUROHIT, KAMLESH Type the URL : Get this ebook

ME6401 KINEMATICS OF MACHINERY UNIT- I (Basics of Mechanism)

ME6401 KINEMATICS OF MACHINERY UNIT- I (Basics of Mechanism) 1) Define resistant body. 2) Define Link or Element 3) Differentiate Machine and Structure 4) Define Kinematic Pair. 5) Define Kinematic Chain.