EBOOK - Design of Hydraulic Systems for Lift Trucks (Ivan Gramatikov) | Cộng đồng Kỹ thuật cơ điện Việt Nam EBOOKBKMT

EBOOK - Thiết kế hệ thống thủy lực cho xe nâng - Tác giả: Ivan Gramatikov (265 Trang).

The purpose of this book is to illustrate design principles and methods for designing and calculating hydraulic systems for industrial lift trucks.
Determining the main parameters of these systems is based on principles of hydraulics and mechanics. This book is to be used as a source of information for mechanical engineers involved in designing, manufacturing and servicing hydraulic systems for mobile lift trucks. This book can also be used by engineering students in Industrial Truck Programs.
To combine these two purposes, there is an introductory chapter, “Properties and Parameters of Hydraulic Fluid”, and a chapter on “Hydraulic Components” describing the construction and the functions of components used in mobile hydraulic systems. This book will also be beneficial for engineers working in areas of design, fabrication and service of any other mobile off-highway equipment.
In all universities, mechanical engineering students study the theoretical foundations of fluid mechanics, fluid dynamics, and thermodynamics. However few universities offer courses in hydraulics and pneumatics (also called: fluid power), which are the applications of these disciplines. That is why most design engineers learn the basics of the fluid power on the job. Fluid power learning time can be reduced significantly if some basic hydraulic principles are understood up front. This book will describe the hydraulic principles and operation of the main hydraulic arrangements
which will give you the foundation for designing any system on your own.
It is more difficult to design hydraulic systems for smaller lift trucks. That is because these systems must have the same performance as the bigger trucks but they have to be put into a smaller space envelope. The smaller design envelope is a major challenge to the design engineers. To meet this
and all other challenges through the design process, engineers have to follow the principles of continuous improvement and design process quality.
Quality of the design process depends on the proper execution of each step 2 Chapter 1: Introductionof the process.
The proper execution requires knowledge in engineering and management areas. The core necessary disciplines are: Mathematics, Mechanics of the Fluids, Hydraulic Circuits and Components, Management of Quality, Project Management, Design for Excellence and Professional
Communication. Some of these courses, in most of the engineering programs, are not part of the engineering curriculum and therefore, engineers must take extra courses in order to acquire the right set of knowledge.
Chapter 4, “Management and Quality of the Design Process”, describes the managerial aspect and the basic principles of the design process.

Chapter 1: Introduction 1
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Definitions for design and system design . . . . . . . . . . . . . 2
Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Systems of units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Symbols used in formulae and hydraulic diagrams . . . . . . 5

Chapter 2: Properties and parameters of the fluids 11
Properties
Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Specific weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Specific gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Compressibility of fluids . . . . . . . . . . . . . . . . . . . . . . 16
Reynolds number and types of flow . . . . . . . . . . . . . 18
Parameters
Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Flow and flow rate . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Fluid velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Work and Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Drag and pressure loss . . . . . . . . . . . . . . . . . . . . . . 25
Hydraulic shock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Hydraulic Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Obliteration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Stiction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Cavitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
The Bernoulli Equation . . . . . . . . . . . . . . . . . . . . . . . . 30
The Torricelli Equation . . . . . . . . . . . . . . . . . . . . . . . . 31

Chapter 3: Hydraulic system components 33
1. Flow Restrictors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2. Pressure Relief Valves . . . . . . . . . . . . . . . . . . . . . . . 36
3. Check Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4. Reduction Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5. Pressure Compensated Flow Controls . . . . . . . . . . . 40
6. Directional Control Valves . . . . . . . . . . . . . . . . . . . . . 42
7. Hydraulic Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8. Hydraulic Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
9. Hydraulic Cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . 60
10. Pressure Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . 64
11. Hydraulic Accumulators . . . . . . . . . . . . . . . . . . . . . 66
12. Hydraulic Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
13. Hydraulic Reservoirs . . . . . . . . . . . . . . . . . . . . . . . . 77
14. Hydraulic Lines, Fittings and Couplings . . . . . . . . . . 83
15. Manifold blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
16. Hydraulic Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
17. Fluid Cleanliness . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
18. Electric Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Chapter 4: Management and quality of hydraulic system
design process 101
Brief history of quality . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Design of Hydraulic Systems for Lift Trucks iii
Structuring the design process . . . . . . . . . . . . . . . . . . . . 106
Definitions of tools used . . . . . . . . . . . . . . . . . . . . . . . . . 108
Description of the design process steps . . . . . . . . . . . . . 110
Design guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Documenting the design activities . . . . . . . . . . . . . . . . . . 117
Project close-out criteria . . . . . . . . . . . . . . . . . . . . . . . . . 118
Failure and failure rate . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Patents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Designing around an existing patent . . . . . . . . . . . . . . . . 122
Legal aspect of the design process . . . . . . . . . . . . . . . . . 123

Chapter 5: Hydraulic systems for high lift trucks 125
Elevating system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Hydraulic systems overview . . . . . . . . . . . . . . . . . . . . . 128
Design principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Design requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Hydraulic system with proportional manual directional valve 133
Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Hydraulic system with electrically controlled proportional valves
Hydraulic system with emergency lowering . . . . . . . . . . 158
Energy recovery systems . . . . . . . . . . . . . . . . . . . . . . . . 160
Hydraulic steering system . . . . . . . . . . . . . . . . . . . . . . . 165
Electro-hydraulic steering system . . . . . . . . . . . . . . . . . . 171
Integrated hydraulic system . . . . . . . . . . . . . . . . . . . . . . 174
Smoothness of the lifting . . . . . . . . . . . . . . . . . . . . . . . . . 176

Chapter 6: Hydraulic systems for low lift trucks 181
Hydraulic system with independent power steering and lift circuits
Integrated hydraulic systems for low lift trucks . . . . . . . . 185
Integrated hydraulic system with accumulator . . . . . . . . 189
Hydraulic system for pallet trucks with long fork attachments 194
Hydraulic power-assisted steering . . . . . . . . . . . . . . . . . 197
Integrated system with power-assisted steering . . . . . . . 199

Chapter 7: Hydraulic systems for boom-type trucks 201
Hydraulic circuit for boom lift, extend and fork tilt . . . . . . . 202
Hydraulic lift & lower circuit for telescopic boom . . . . . . . 203
Hydraulic circuit with an automatic shut-off valve . . . . . . 207
High-speed extension of telescopic boom . . . . . . . . . . . . 208

Chapter 8: Selected topics 211
I. Servicing the hydraulic systems . . . . . . . .211
Troubleshooting principles . . . . . . . . . . . . . . . . . . . . . . . . 212
System Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Safety Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Servicing the fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Servicing filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Servicing reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Servicing rotary pumps and motors . . . . . . . . . . . . . . . . . . 217
Servicing hydraulic cylinders . . . . . . . . . . . . . . . . . . . . . . . . 218
Servicing valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
Servicing connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Design of Hydraulic Systems for Lift Trucks v
II. Components layout- general considerations 222
III. Common problems . . . . . . . . . . . . . . . . . . . . . 223
IV. Contamination of the hydraulic fluid . . . . . . 225
V. The future of the hydraulics . . . . . . . . . . . . . 229

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