Working as a practicing engineer for a major US airline, I found this book a very useful introduction to hydraulics & pneumatics. Using this book, I was able to take systems on our airplanes (such as rudder control units and thrust reverser controllers) and write schematics of them using the hydraulic & pneumatic notation. I found the chapter on process control pneumatics to be quite useful in troubleshooting & understanding these systems. While I use this information on aircraft systems, the book is directed to hydraulic & pneumatics in ALL industries and no reference is made to hardware as installed in aircraft applications. Check valves, relief valves, accumulators, pilot valves and sequencing valves are well explained to the layman. The author does a great job explaining the dynamics of cylinders and valves with lots of timing diagrams and schematics. Pick this book up if you want to come up to speed quickly on hydraulics and pneumatics.