iii Preface This book is the outcome of many years of persistent interest in fl uid power, beginning with the operation of farm equipment and involvement in a 4H tractor-maintenance project when I was a teenager, continuing throughout my college years and far into my professional life. Partly, the fascination came from the science foundations that are there and partly from the practical applications that brought those abstract concepts to life. There is orderliness to hydraulics and pneumatics that, beyond the work accomplished, has a sense of aesthetics. So the study of fl uid power and the challenge of teaching oth- ers to use it has been a satisfying journey. Our lives would be very different today if early civilizations had not recognized the potential of using air and water to do work. From the fi rst rough waterwheels and windmills to the sophisticated applications we see today, fl uid power has enabled us to do what was, in many cases, fi rst thought to be impossible. Now, with computer inter- faces, new materials, and imaginative technology to help us, we may be just at a new dawn of breakthroughs to come. The purpose of this book is to introduce you to the fi eld of fl uid power. It lays the groundwork for building an understanding of the concepts involved and systemati- cally guides the use of these concepts in designing functional circuits. Purposefully, the questions asked will require problem solving and creative thinking that is what real life requires. Mastery of the subject matter is not easy, but careful study and thoughtful experimentation will make it happen. Many individuals, companies, and organizations have contributed to this learning resource. I wish to acknowledge their assistance and express my sincere appreciation to them all. Likewise, I am deeply grateful to the publisher, Goodheart-Willcox, for contin- ued encouragement and support while this was written. I hope the book will be a useful tool for the fi eld. —Jim Daines About the Authors James R. Daines is Professor Emeritus of Technology at the University of Wisconsin— Stout. He holds an EdD degree from the University of Missouri and BS and MS degrees from Stout State College, Menomonie, Wisconsin. Professional experience includes 25 years teaching power- and media-related courses to secondary, postsecondary, and adult students. In addition, 10 years were spent as president of a company specializing in developing courses and instructional materials for power and other related technolo- gies. Those materials included extensive computer-based courses for hydraulics and pneumatics. Other experiences related to fl uid power involved working on the design and construction of training benches and instructional materials for a producer of fl uid power training equipment. Martha J. Daines holds a PhD from the University of Chicago and a BS degree from the University of Wisconsin—Madison. Martha’s professional experience includes 10 years investigating multiphase fl ow in high-pressure environments and 15 years teaching technology and power courses to students at the University of Wisconsin—Stout.