book presents a new approach to the study of fluid power. Although there are parts inspired from material that can be found in other books, slides, classes or training manuals, the logic used to organize and present the design aspects of fluid power systems and the focus on real applications is completely original and unique. For these reasons, the authors are convinced that this manuscript is an excellent resource for both undergraduate and graduate level engineering classes. Furthermore, it is a reference guide that belongs on the desk of every hydraulic engineer in the industry.
Acknowledgments
The authors acknowledge many of the mentors that they had the privilege to work with: the already mentioned Prof. Nicola Nervegna, Prof. Gian Luca Zarotti, Jarmo Harsia, and Leslie Claar. More importantly, the authors firmly believe that this book would have never come to life if it had not been for Prof. Monika Ivantysynova. Both authors admired her passion and talent for fluid power research and credit her with many of the successes in their careers and personal lives. It is also thanks to her that both authors had the chance to reconnect in the USA.
The writing of the book involved also two co‐authors who were very helpful in the development of some chapters. Gabriele Altare was part of the initial team and provided a tremendous support in the illustrations and writing of Chapters 4 and 5–9, while Lizhi Shang was instrumental in the chapter dedicated to hydrostatic pumps and motors (see chapter 6).
The authors' work was reviewed by several people: the graduate students of the Maha Fluid Power Research Center (class of 2019), Pradeep Gillella, Barun Acharya, and other members of Parker Hannifin, who all provided tremendous help with chapter reviews and suggestions for improvement.
Finally, both authors want to give a special thanks to their loving wives, Jing and Sarah, who supported us during this multiple years' journey and accepted us being away from home on numerous weekends.
Part I Fundamental Principles
The first part of this book is dedicated to the description of the fundamental laws, concepts, and conventions that are necessary to comprehend the functioning of hydraulic circuits and hydraulic components.
Chapter 1 contains a brief introduction of the hydraulic control technology and an explanation of the symbology used to illustrate hydraulic circuits.
Chapter 2 gives an overview of the properties of hydraulic fluids and how their properties can affect the operation of a component or a circuit. It also illustrates the detrimental effects of fluid cavitation, aeration, and contamination.
Chapter 3 recalls fundamental concepts derived from fluid mechanics, which are useful to describe the operation of fluid power components.
Subsequently, Chapter 4 is dedicated to the orifice, which is one of the most important conceptual elements of hydraulic control circuits. Orifices can have multiple functions and variable orifices can be used to describe the operation of many hydraulic components. The orifice equation will be repeatedly used throughout the manuscript.
Although the focus of the book is on the steady‐state operation of hydraulic machines and circuits, Chapter 5 introduces the reader to the basic analysis of transient operation of hydraulic circuits.
Objectives
Part I aims to familiarize the reader with the fundamental concepts and equations that will be used for the analysis of hydraulic circuits and hydraulic components. A reader already familiar with these concepts is still recommended to peruse the chapters of Part I, to be clear with the symbology and conventions used throughout the manuscript. After a thorough understanding of the contents presented in Part I, including the worked examples as well as the completion of the problems at the end of each chapter, the reader will be able to
1 Interpret circuits drawn with symbols of the ISO standard of representation.
2 Discuss the most common hydraulic fluids and describe the most important fluid properties affecting the operation of a hydraulic system.
3 Describe the concept of fluid cavitation or aeration and determine the effect on the fluid properties.
4 Describe the detrimental effects of solid contaminants in a hydraulic system.
5 Identify sources of energy loss, as turbulent or laminar hydraulic resistance.
6 Analyze flow forces in hydraulic components resulting from variation of fluid momentum.
7 Analyze the steady‐state operation of a flow network, based on the pressure law and flow law.
8 Derive the orifice equation starting from the fundamental Bernoulli equation.
9 Recognize the function of a specific orifice in a hydraulic network.
10 Discuss the concept of hydraulic resistance, hydraulic capacitance, and hydraulic inductance and their effects on the transient response of basic hydraulic systems.
11 Apply the concept of hydraulic resistance, hydraulic capacitance, and hydraulic inductance for basic analyses of hydraulic transients.
Chapter 1 Introduction to Hydraulic Control Technology
Hydraulic control systems are used across many engineering applications to provide motion and force control of mechanical systems. With respect to competing technologies for transmitting mechanical power (i.e. mechanical drives or electrical drives), hydraulic drives offer favorable characteristics from both the power to weight ratio and control perspectives. State‐of‐art hydraulic systems can be up to 1 order of magnitude lighter than electric systems with the same power (or torque) level. Also, compared with mechanical drives, hydraulic systems offer a greater layout flexibility thanks to the versatile design of the piping or hose system that connects the hydraulic components. Hydraulic drive technology also easily offers solutions for advanced actuator control, in terms of output velocity and force, motion reversals, and safety functions. These mentioned features are particularly advantageous in applications involving the transmission of large amounts of power. For this reason, hydraulics is a consolidated technology in many heavy‐duty applications, in manufacturing industry (hydraulic presses, molding machines, machining robots, etc.), and in mobile applications (construction, agriculture, aerospace, military, and marine). Recent progress in component miniaturization and interfacing with electronic controls have also brought hydraulic systems into emerging fields such as biomedical engineering (surgery robots, patient transfer and rehabilitation devices, etc.).
However, compared with other technologies for power transmission and motion control, hydraulics has some significant drawbacks, the most important one being the inevitable presence of energy losses. Depending on the application, other disadvantages might affect hydraulic systems, such as the high influence of temperature
