CONTENTS Preface XI Preface to the First Edition xiii Abbreviations XV Part I HYDRAULICS 1.Fluid Power Systems and Fundamentals 3-13 1.1 Introduction 3 1.2 Advantages of Fluid Power 5 1.3 Disadvantages of Fluid Power Systems 5 1.4Applications of Fluid Power Systems 5 1.5 Types of Fluid Power Systems6 1.5.1Hydrostatic System 6 1.5.2Hydrodynamic System7 1.6Hydraulic Fluids7 1.6.1Power Transmission or Energy Transfer 1.6.2Lubrication 9 1.6.3Sealing9 1.6.4Cooling 9 1.7 Fluid Characteristics 10 1.7.1Viscosity10 1.7.2Pour Point 10 1.7.3Oxidation Resistance10 1.7.4Rust and Corrosion10 1.7.5Demulsibility 10 1.8 General Types of Fluid 12 ? 1.8.1High Water Fluids (HFA) 12 1.8.2Water in Oil (HFB) 12 1.8.3Water Glycol (HFC) 12 1.8.4Synthetics (HFD) 12 Review Questions 12 IV Contents 2.Basics of Hydraulics 14-22 2.1 Governing Principles 14 2.1.1Liquid is Noncompressible 14 2.1.2Pressure 14 2.1.3Flow Rate 15 2.1.4Oil Flow Path 75 2.1.5Pascal's Law and Its Application 15 2.1.6Pressure Drop 16 2.2 Flow of Hydraulic Fluid 76 2.2.1Laminar Flow 76 2.2.2Turbulent Flow 77 2.2.3Practicality of Laminar/Turbulent Flows 77 2.2.4Bernoulli's Principle 77 2.3 Reynolds Number 79 2.4 Friction Losses in Flows through Hydraulic Systems 20 2.5 Darcey-Weisbach Formula 20 2.6 Losses in Pipe Valves and Fittings 20 Review Questions 21 3.Hydraulic Systems and Components 23-43 3.1 Sources of Hydraulic Power 23 3.1.1Hydraulic System Arrangement 23 3.2 Pumping Theory 26 3.2.1Positive Displacement Pumps 26 3.2.2Pump Parameters 27 3.3 Pump Classification 28 3.3.1Pump Types Based on Delivery of Oil Flow 29 3.4 Gear Pumps 30 3.4.1Characteristics of Gear Pumps 32 3.5 Vane Pumps 33 3.5.1Unbalanced Forces in Vane Pumps 33 3.5.2Characteristics of Vane Pumps 35 3.6 Piston Pumps 36 3.6.1Fixed Displacement Radial Piston Pumps 36 3.6.2Axial Piston Pumps 38 3.6.3Bent Axis Piston Pump 41 Review Questions 42 4.Fluid Power Actuators 44-62 4.1 Hydraulic Actuators 44 4.2Hydraulic Cylinders 44 4.2.1Types of Hydraulic Cylinders 44 4.2.2 Construction of Hydraulic Cylinders 45 4.2.3 Single-acting and Double-acting Cylinders 47 4.2.4 Special Hydraulic Cylinders-Telescopic and Tandem 49 4.2.5 Specifications of a Hydraulic Cylinder 51 4.2.6 Cushioning in Hydraulic Cylinders 52 4.3 Hydraulic Motors 53 4.3.1 Principle of Working of Hydraulic Motors 53 4.3.2 Types of Hydraulic Motors54 4.3.3 Further Selection Criteria for Hydraulic Motors 55 4.3.4 Gear Motors 56 ?4.3.5 Vane Motors 57 4.3.6 Piston Motors 58 4.3.7 Useful Formulae 59 4.3.8 Hydraulic Motors in Circuits 59 4.3.9 Comparison of Hydraulic Motor with Electric Motor Drives 61 Review Questions 62 5. Hydraulic Elements in the Design of Circuits-I 63-86 5.1 Introduction to the Design of Hydraulic Circuits 63 5.2 Control Elements63 5.2.1Functions of Control Elements 63 5.3 Direction Control Valve64 5.3.1Classification of Direction Control Valves 65 5.3.2Spool Movement by Solenoids70 5.3.3Pilot-operated Direction Control Valves71 5.4 Check Valves73 5.4.1 Pilot-operated Check Valves74 5.5 Pressure Control Valves76 5.5.1Pressure Relief Valve76 5.5.2 .Unloading Relief Valve or Solenoid-operated Relief Valve 80 5.5.3Pressure-reducing Valve 81 5.5.4Counterbalance Valve 82 5.5.5Sequence Valve 84 Review Questions 86 6.Hydraulic Elements in the Design of Circuits-II 87-98 6.1 Flow and Pressure 87 6.2 Flow Control Valve and Its Effect on Relief Valve in the System 88 6.2.1Effects of Temperature and Pressure on Flow Control Valves 89 6.3 Throttle Valves 90 6.3.1Throttle Valve without Free Reverse Flow90 6.3.2Throttle Valve with Free Reverse Flow 91 6.4 Flow Control Valves with Temperature and Pressure Compensation 91 6.5 Locations of Flow Control Valve 94 6.4.1Pressure Compensation in Flow Control Valves 92 6.4.2Function of Antijump Feature 93 6.4.3Temperature Compensation in Flow Control Valves 9J 6.5.1Meter-in Control 94 6.5.2Meter-out Circuit 95 6.5.3Bleed-off Circuits 97 Review Questions 97 7.Accumulators and Intensifiers 99-109 7.1 Function of Accumulators 99 7.2 Types of Hydraulic Accumulators 99 7.2.1Weighted Accumulators 99 7.2.2Spring-loaded Accumulators 100 7.2.3Gas-charged Accumulators 100 7.3 Size of Accumulators 102 7.4 Accumulator-Application and Circuits 103 7.4.1Fluid Power Storage 103 7.4.2Accumulator as a Pressure Compensator 105 7.4.3Accumulator as a Shock Absorber 105 7.4.4Accumulator for Emergency Operation 105 1.5 Accessories for Accumulators 705 7.5.1Unloading Relief Valve 106 7.5.2Pressure Switch 106 7.6 Intensifiers 707 7.6.1Applications of Intensifier 108 7.6.2Intensifier Circuit 108 Review Questions 109 8.Design of Hydraulic Circuits 110-116 8.1 Introduction 110 8.2 A Typical Customer's Summary of Requirements/Specifications Review Questions 116 9.Drawing of Hydraulic Circuits 117-123 9.1 How to Draw a Hydraulic Circuit 117 9.2 Reciprocation of Hydraulic Actuator (Hydraulic Cylinder) 121 9.3 Quick Return of a Hydraulic Cylinder 122 Review Questions 122 10. Fluid Power in Machine Tools and Other Equipment 124-143 10.1 Introduction124 10.2 Hydraulic Clamping Circuits in Machine Tools 124 10.3 Clamping the Job 126 10.4 Hydraulic Circuits for Feed Operation in Machine Tools 128 10.5 Speed Control in One Direction (DCV and FCV Combination) 129 10.6 Meter-in Feed Circuit (DCV and FCV Combination) 130 10.7 Meter-out Circuit (DCV and FCV Combination) 130 10.8 Speed Control in Both Directions (DCV and FCV Combination)- Tank Line Feed Control 132 10.9 Standard Manifold for Dual Speed 133 10.10 Hydraulic Circuits for Plastic Injection Moulding Machine 136 10.11 Hydraulic Press Application 138 Review Questions 143 Part II PNEUMATICS 11. Pneumatic Systems-Concepts and Components 147-166 11.1 Introduction 147 11.2 Comparison of Pneumatic/Hydraulic/and Electrical Systems 148 11.3 Air-Compression System149 11.4 Types of Compressors 150 11.5 Compressor Specifications 157 11.6 Arrangement of a Complete Pneumatic System 157 11.6.1 Air-Generation System 152 11.6.2Air-Preparation System 152 11.7 Compressed Air Behaviour 155 11.8 Compressed Air Application in Spray Painting 155 11.9 Understanding Pneumatic Circuits 156 11.9.1 Pneumatic Actuators 157 11.10 Direction Control Valves 158 11.10.1 Ways and Positions of Direction Control Valves 161 11.10.2 Few Important Characteristics of Pneumatic Direction Control Valves 162 Review Questions 166 12. Design of Pneumatic Circuits-I 167-182 12.1 Fluid Power Circuit Design (Pneumatics) 167 12.2 Illustrations 168 12.3 Switching Positions of Valves 169 VIII Contents 12.4 Control Air vs Signal Air 169 12.5 Notation/Numbering of Valves170 12.6 Building a Pneumatic Circuit 172 12.7 Application of Logic Valves-AND, OR Gates 174 12.8 Speed Control Circuits776 12.9 Application of Time Delay Valves 179 Review Questions181 13. Design of Pneumatic Circuits-II 183-193 13.1 Position Sensing in Pneumatic Cylinders 183 13.2 Signal Flow for Pneumatic Circuit for Pressure Sensing 185 13.3 Roller Lever Valve and Roller Lever Valve with Idle Return 186 13.4 Notation of Roller Lever Valve and Roller Lever Valve with Idle Return in Pneumatic Circuits 13.5 Pressure Sensing in Pneumatic Circuits 189 13.6 Pressure Sequence Valve 189 Review Questions 192 14. Multicylinder Pneumatic Circuits 194-211 14.1 Two Cylinders Movement 194 14.2 Overlapping of Signals 198 14.3 Displacement Diagrams 199 14.4 Displacement Diagrams of Multicylinder Operations 200 14.5 Cascade Method-Sequential Circuit Design 201 14.6 Stepper Sequencer or Counter Method of Drawing Pneumatic Circuits 207 Review Questions210 15. Electropneumatics 212-229 15.1 Introduction 212 15.2 Pilot-operated Solenoid Valve 213 15.3 Electrical Connections to the Solenoids 214 15.4 Electropneumatic Circuit-Switches 215 15.5 Electrical Limit Switches and Proximity Switches 216 15.6 Relays 277 15.7 Solenoids 279 15.8 P.E. Converter 220 15.9 The Concept of Latching 222 Review Questions 227 Contents IX Part III APPLICATIONS OF HYDRAULICS AND PNEUMATICS 16. Servo Systems 233-239 16.1 Introduction 233 16.2 Closed-loop Control with Servo System 234 16.3 Hydromechanical Servo System 234 16.4 Electrohydraulic Servo Valve System 235 16.5 Conventional Valves vs Proportional Valves 235 16.6 Proportional Valves 237 16.7 Proportional Valves in Hydraulic Circuits 237 16.8 Advantages of Proportional Valves over Conventional Valves 23* 16.9 Hydraulic Circuit with Proportional Valves 23* 16.10 Characteristics of Proportional Valvesand Servo Valves 239 Review Questions 239 17. PLC Applications in Fluid Power 240-256 17.1 Introduction 240 17.2 Input and Output Devices 242 17.3 Logic in Ladder Diagrams and Mnemonics 243 17.4 Timers-On Delay and Off Delay 247 Review Questions 254 18. Failure and Troubleshooting in Fluid Power Systems 257-260 18.1 Introduction 257 18.2 Troubleshooting-Oil Hydraulics 257 18.3 Troubleshooting-Pneumatics 257 Review Questions 259 Part IV APPENDICES Appendix 1 Subplates and Manifolds 263-267 Appendix 2 Introducing Cartridge Valves 268-271 Appendix 3 Terminologies Used in Fluid Power 272-273 Appendix 4 Hydraulic Symbols 274-276 Appendix 5 Useful Data and Units 277 Appendix 6 Multiples and Submultiples 278 Appendix 7 Hydraulic Fluid Characteristics 279 Appendix 8 Standard and Popular Bore and Rod Diameters of Hydraulic Cylinders 280 Appendix 9 Popular Symbols Used in Pneumatic Circuits 281-285 Appendix 10 Solutions to Selected Pneumatic/ Electropneumatic Circuit Problems 286-295 Bibliography 297 Index 299-302