(For B.E. / B.Tech Mechanical Engineering Students)

As per the Latest Syllabus of Anna University

Email : aishram2006@gmail.com, airwalk800@gmail.com

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80, KARNEESHWARA KOIL STREET,

(Near All India Radio) MYLAPORE, CHENNAI - 4

Ph.: 044 - 24661909, 9444081904

AIRWALK PUBLICATIONS

Hydraulics andPneumatics

Professor - Mech Sathyabama Institute of Science & Technology

Chennai - 600 119.

Dr. P. Senthil KumarPrincipal

KSR Engineering College Thiruchengode

150/-

and

First Edition : 25-01-2004Second Edition : 16-11-2019

www.airwalkbooks.com www.srbooks.org and

Cell: 9600003081, 9600003082

Typeset by: aksharaa muthra aalayam pvt. ltd., Chennai - 18. Ph.: 044-2436 4303

ISBN: 978-93-88084-51-2

ISBN: 978-93-88084-51-2

ME8694 HYDRAULICS AND PNEUMATICS

UNIT I: FLUID POWER PRINICIPLES AND HYDRAULIC

PUMPS 9

Introduction to Fluid power – Advantages and Applications –

Fluid power systems – Types of fluids – Properties of fluids and

selection – Basics of Hydraulics – Pascal’s Law – Principles of flow

Friction loss – Work, Power and Torque Problems, Sources of

Hydraulic power: Pumping Theory – Pump Classification –

Construction, Working, Design, Advantages, Disadvantages,

Performance, Selection criteria of Linear and Rotary – Fixed and

Variable displacement pumps – Problems.

UNIT II: HYDRAULIC ACTUATORS AND CONTROL

COMPONENTS 9

Hydraulic Actuators: Cylinders – Types and construction,

Application, Hydraulic cushioning – Hydraulic motors – Control

Components: Direction Control, Flow control and pressure control

valves – Types, Construction and Operation – Servo and Proportional

valves – Applications – Accessories: Reservoirs, Pressure Switches –

Applications – Fluid Power ANSI Symbols – Problems.

UNIT III: HYDRAULIC CIRCUITS AND SYSTEMS 9

Accumulators, Intensifiers, Industrial hydraulic circuits –

Regenerative, Pump Unloading, Double-Pump, Pressure Intensifier,

Air-over oil, Sequence, Reciprocation, Synchronization, Fail – Safe,

Speed Control, Hydrostatic transmission, Electro hydraulic circuits,

Mechanical hydraulic servo systems.

UNIT IV: PNEUMATIC AND ELECTRO PNEUMATIC

SYSTEMS 9

Properties of air – Perfect Gas Laws – Compressor – Filters,

Regulator, Lubricator, Muffler, Air control Valves, Quick Exhaust

Valves, Pneumatic actuators, Design of Pneumatic circuit – Cascade

method – Electro Pneumatic System – Elements – Ladder diagram –

Problems, Introduction to fluidics and pneumatic logic circuits.

UNIT V: TROUBLE SHOOTING AND APPLICATIONS 9

Installation, Selection, Maintenance, Trouble Shooting and

Remedies in Hydraulic and Pneumatic systems, Design of hydraulic

circuits for Drilling, Planning, Shaping, Surface grinding, Press and

Forklift applications. Design of Pneumatic circuits for Pick and Place

applications and tool handling in CNC Machine tools – Low cost

Automation – Hydraulic and Pneumatic power packs.

TOTAL:45 PERIODS

Table of Contents

UNIT I:

FLUID POWER PRINCIPLES AND HYDRAULIC PUMPS

1.1 Introduction to Fluid Power . . . . . . . . . . . . . . . . . . . . 1.1

1.2 Advantages of Fluid Power. . . . . . . . . . . . . . . . . . . . . 1.2

1.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3

1.4 Fluid Power System. . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4

1.5 Properties of Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

1.5.1 Gas and Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

1.5.2 Density (or) mass Density . . . . . . . . . . . . . . . . . . . . . . 1.6

1.5.3 Specific weight (or) Weight density. . . . . . . . . . . . . . . 1.6

1.5.4 Specific Volume (v) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7

1.5.5 Specific gravity (or) Relative density (s) . . . . . . . . . . 1.7

1.5.6 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8

1.5.7 Viscosity (Dynamic Viscosity). . . . . . . . . . . . . . . . . . . . 1.9

1.5.8 Compressibility ⎛⎜⎝ 1K

⎞⎟⎠

. . . . . . . . . . . . . . . . . . . . . . . . . . 1.14

1.5.9 Vapour Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.16

1.5.10 Surface Tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.19

1.5.11 Capillarity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.25

1.5.12 Thermodynamic Properties . . . . . . . . . . . . . . . . . . . . 1.27

1.6 Newton’s Law of Viscosity . . . . . . . . . . . . . . . . . . . . 1.30

1.7 Selection of Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.38

1.8 Hydraulic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.44

1.9 Basics of Hydraulics-Hydraulic Principles . . . . . . . 1.45

1.10 Principles of Fluid Flow . . . . . . . . . . . . . . . . . . . . . 1.50

1.11 Types of Newtonian Fluid . . . . . . . . . . . . . . . . . . . 1.56

Contents C.1

1.12 Friction Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.58

1.13 Work, Power and Torque Problems. . . . . . . . . . . . 1.60

1.14 Sources of Hydraulic Power - Pumping Theory . 1.64

1.15 Pump Classification . . . . . . . . . . . . . . . . . . . . . . . . . 1.65

1.16 Gear Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.68

1. External gear pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.68

2. Internal gear pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.69

3. Lobe pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.70

4. Gerotor Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.71

5. Screw Pumps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.72

1.17 Vane Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.72

1. Unbalanced Vane pump . . . . . . . . . . . . . . . . . . . . . . . . . 1.72

2. Balanced Vane pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.73

3. Variable displacement Vane pump . . . . . . . . . . . . . . . . 1.74

4. Pressure compensated variable displacement pump . . 1.75

1.18 Piston Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.75

1. Axial pump with swash plate . . . . . . . . . . . . . . . . . . . . 1.76

2. Bent-Axis Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.77

3. Radial Piston Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.79

4. Piston pump with stationary cam and rotating block 1.79

1.19 Pumps Performance Characteristics . . . . . . . . . . . 1.81

1.20 Pump Selection Criteria . . . . . . . . . . . . . . . . . . . . . 1.84

UNIT II:

HYDRAULIC ACTUATORS AND CONTROL COMPONENTS

2.1 Hydraulic and Pneumatic Actuators . . . . . . . . . . . . . 2.1

2.2 Cylinders – Linear Actuators: . . . . . . . . . . . . . . . . . . 2.2

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2.2.1 Single acting Hydraulic and Pneumatic cylinder

(actuator) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2

2.2.2 Double acting Hydraulic and Pneumatic cylinder

(actuator) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4

2.2.3 Hydraulic Cylinder Cushioning. . . . . . . . . . . . . . . . . . 2.5

2.2.4 Side loads and the stop tube . . . . . . . . . . . . . . . . . . . 2.9

2.2.5 Telescopic cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.11

2.2.6 Through Rod cylinder. . . . . . . . . . . . . . . . . . . . . . . . . 2.12

2.2.7 Tandem cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.12

2.2.8 Turn Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13

2.3 Hydraulic Motors (Rotary Actuators) . . . . . . . . . . . 2.13

2.3.1 Gear Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.15

2.3.2 Vane Motor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.15

2.3.3 Piston Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16

2.4 Control Components (Hydraulic Valves) – Direction Control – Pressure – Flow Control . . . . . . . . . . . . . 2.17

2.5 Direction Control Valves . . . . . . . . . . . . . . . . . . . . . . 2.20

2.5.1 Pilot operated check valve . . . . . . . . . . . . . . . . . . . . . 2.23

2.5.2 Two way valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.24

2.5.3 Four way valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.25

2.5.4 Various flow configurations of Four way three

position Valves (4/3 valves) . . . . . . . . . . . . . . . . . 2.32

2.5.5 Rotary Four way valves . . . . . . . . . . . . . . . . . . . . . . . 2.33

2.5.6 Shuttle Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.34

2.6 Pressure Control Valves . . . . . . . . . . . . . . . . . . . . . . 2.35

2.6.1 Pressure Relief Valve . . . . . . . . . . . . . . . . . . . . . . . . . 2.37

2.6.2 Compound Relief valve . . . . . . . . . . . . . . . . . . . . . . . . 2.38

2.6.3 Pressure Reducing Valve . . . . . . . . . . . . . . . . . . . . . . 2.39

Contents C.3

2.6.4 Unloading Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.40

2.6.5 Sequence Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.41

2.6.6 Counter Balance Valve . . . . . . . . . . . . . . . . . . . . . . . . 2.43

2.7 Hydraulic Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.44

2.7.1 Pressure Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.45

2.7.2 Temperature Switch . . . . . . . . . . . . . . . . . . . . . . . . . . 2.50

2.8 Flow (Process) Control Valves . . . . . . . . . . . . . . . . . 2.51

2.8.1 Needle Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.51

2.8.2 Easy Read and Adjust Flow Control Valves. . . . . . 2.51

2.8.3 Globe valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.52

2.8.4 Gate valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.52

2.8.5 Non-pressure compensated flow control valve . . . . . 2.53

2.8.6 Pressure compensated flow control valve . . . . . . . . . 2.55

2.8.7 Servo Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.56

2.8.8 Non-adjustable compensated flow control valve . . . 2.57

2.8.9 Flow Control Valve Symbols . . . . . . . . . . . . . . . . . . . 2.58

2.9 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.59

2.10 Reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.58

2.11 Accessories – More Explanations . . . . . . . . . . . . . . 2.62

2.11.1 Hydraulic Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . 2.63

2.11.2 Filters and strainers . . . . . . . . . . . . . . . . . . . . . . . . . 2.65

2.11.3 Sealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.71

2.11.4 Hydraulic Accumulators . . . . . . . . . . . . . . . . . . . . . . 2.72

2.11.5 Pressure Intensifiers (or) Boosters . . . . . . . . . . . . . . 2.76

2.11.6 Hydraulic coolers and heaters (Heat exchangers) . 2.76

2.12 Fluid Power ANSI Symbols . . . . . . . . . . . . . . . . . . 2.78

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UNIT III:

HYDRAULIC CIRCUITS AND SYSTEM

3.1 Hydraulic Circuits and Systems . . . . . . . . . . . . . . . . 3.1

3.2 Single Acting Hydraulic Cylinder Circuit. . . . . . . . . 3.1

3.3 Double Acting Hydraulic Cylinder Circuit . . . . . . . . 3.3

3.4 Continuous Reciprocation Circuit. . . . . . . . . . . . . . . . 3.4

3.5 Quick Return Motion Circuits . . . . . . . . . . . . . . . . . . 3.5

3.6 Sequencing Circuit (Hydraulic Circuits for Drilling) 3.7

3.7 Synchronising Circuits . . . . . . . . . . . . . . . . . . . . . . . . . 3.9

3.8 Accumulator Circuits . . . . . . . . . . . . . . . . . . . . . . . . . 3.11

3.9 Fail-safe Circuits (Safety Circuits) . . . . . . . . . . . . . 3.19

3.10 Pressure Intensifier Circuit (or) Punching press Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.21

3.11 Hydraulic Circuit for table movement of Milling Machine (or) Surface Grinder . . . . . . . . . . . . . . . . 3.22

3.12 Design of Speed Control Circuits . . . . . . . . . . . . . 3.24

3.13 Meter out Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.24

3.14 Hydraulic Fork Lift Circuits (Meter-in Circuit). . 3.25

3.15 Bleed Off Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.27

3.16 Regenerative Circuit . . . . . . . . . . . . . . . . . . . . . . . . 3.28

3.17 Counter Balance Valve Circuits. . . . . . . . . . . . . . . 3.31

3.18 Double Pumps in Hydraulic Circuits . . . . . . . . . . 3.32

UNIT IV:

PNEUMATIC AND ELECTRO PNEUMATIC SYSTEMS

4.1 Pneumatic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1

4.2 Important Properties of Air . . . . . . . . . . . . . . . . . . . . 4.5

4.3 Perfect Gas Laws (Ideal Gas Laws) . . . . . . . . . . . . . 4.6

Contents C.5

1. Boyle’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

2. Charle’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

3. Gay-Lussac’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

4.4 Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

4.5 Pneumatic Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8

4.5.1 Filters - Regulator - Lubricator . . . . . . . . . . . . . . . . . 4.9

4.6 Air Control Valves - Control Elements In Pneumatic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10

4.7 Pneumatic Actuators – Single Acting Air cylinder 4.19

4.8 Pneumatic Actuators – Double-acting Cylinder . . . 4.20

4.10 Design of Pneumatic Circuits. . . . . . . . . . . . . . . . . 4.24

4.11 Classic (or) Intuitive Method . . . . . . . . . . . . . . . . . 4.24

4.12 Cascade Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.27

4.13 Step Counter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.30

4.14 PLC and Microprocessor Uses . . . . . . . . . . . . . . . . 4.32

4.15 Introduction to Fluidic and Pneumatic Logic circuits 4.36

4.16 Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.43

4.17 Control of Cylinders Using Switches . . . . . . . . . . 4.50

4.18 Regenerative System With Switches . . . . . . . . . . . 4.51

4.19 Electro Pneumatic System . . . . . . . . . . . . . . . . . . . 4.52

4.20 Electro Hydraulic Circuits . . . . . . . . . . . . . . . . . . . 4.53

4.21 Robotic Circuits – Mechanical Hydraulic Servo System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.54

4.22 Ladder Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.56

4.22.1 Symbols used in Ladder Programming . . . . . . . . . 4.57

4.22.2 Functional Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.59

4.23 Logic Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.61

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4.24 Real Time Programming Example. . . . . . . . . . . . . 4.70

4.24.1 Latching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.71

4.25 Automatic Retraction of Air Cylinders . . . . . . . . . 4.72

4.26 Continuous Reciprocation of Air Cylinders. . . . . . 4.76

UNIT V: TROUBLE SHOOTING AND APPLICATIONS

5.1 Selection Criteria For Pneumatic Components . . . . 5.1

5.2 Air Compressor Selection . . . . . . . . . . . . . . . . . . . . . . 5.1

5.3 Piston Seals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4

5.4 Seal Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4

5.5 Seal Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6

5.6 Piston Rod Seals for Cylinders . . . . . . . . . . . . . . . . 5.12

5.7 Other Components . . . . . . . . . . . . . . . . . . . . . . . . . . 5.14

5.8 Conditioning of Compressed Air . . . . . . . . . . . . . . . 5.14

5.9 FRL Assembly (Trio Assembly): . . . . . . . . . . . . . . . . 5.15

5.10 Air Line Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.16

5.11 Air Pressure Regulator . . . . . . . . . . . . . . . . . . . . . . 5.17

5.12 Air Line Lubricators . . . . . . . . . . . . . . . . . . . . . . . . 5.21

5.13 Atomizer-type Air Line Lubricators. . . . . . . . . . . . 5.22

5.14 Dryers For Compressed Air . . . . . . . . . . . . . . . . . 5.23

5.15 Refrigeration-type Air Dryers . . . . . . . . . . . . . . . . . 5.26

5.16 Dessicant-type Twin Tower Heatless Dryer . . . . . 5.27

5.17 Plumbing Compressed Air Systems. . . . . . . . . . . . 5.28

5.18 Selecting Pipe Size For Compressed Air Flow . . 5.30

5.19 Installation and Maintenance of Fluid Power Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.33

5.19.1 Fault Finding and Maintenance of fluid power

systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.34

Contents C.7

5.19.2 Leakage Testing of cylinder and valves . . . . . . . . . 5.35

5.20 Trouble Shooting and Remedies in Hydraulic and Pneumatic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 5.37

5.21 Design of Hydraulic Circuits for Drilling . . . . . . . 5.44

5.22 Design of Hydraulic Circuits for Planing . . . . . . . 5.44

5.23 Design of Hydraulic Circuits for Shaping . . . . . . 5.44

5.24 Design of Hydraulic Circuits for Surface grinding 5.44

5.25 Design of Hydraulic Circuits for Press. . . . . . . . . 5.44

Forklift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.44

5.26 Tool Handling In CNC Machine Tools . . . . . . . . . 5.45

5.27 Hydraulic Clamping Circuits . . . . . . . . . . . . . . . . . 5.45

5.28 Hydraulic Circuits for Feed Operation (Drilling) 5.50

5.29 Meter In Feed Circuit . . . . . . . . . . . . . . . . . . . . . . . 5.53

5.30 Meter Out Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . 5.54

5.31 Speed Controls in Both Directions - Tank Line Feed Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.56

5.32 Low Cost Automation . . . . . . . . . . . . . . . . . . . . . . . 5.63

5.33 Hydraulic and Pneumatic Power Packs . . . . . . . . 5.64

5.34 Sample Calculation Illustrating Boyle’s Law . . . . 5.67

5.35 Understanding Cylinder Operation . . . . . . . . . . . . 5.68

5.36 Selection of Hydraulic Components . . . . . . . . . . . 5.71

5.36.1 Selection of hydraulic accumulator. . . . . . . . . . . . . 5.75

5.36.2 Selection of Heat Exchanger . . . . . . . . . . . . . . . . . . 5.79

5.36.3 Cylinder Mounting Arrangement. . . . . . . . . . . . . . . 5.81

5.37 Cylinder Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . 5.82

5.38 Fluid Power Definitions. . . . . . . . . . . . . . . . . . . . . . 5.86

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