This text is the second in a series reporting on the International Fluid Power Research Workshops held annually in Bath, England. Consisting of the proceedings of the 1989 meeting, the book explores a variety of areas, indicating the breadth of research and development in fluid power components and systems. Among the topics discussed are energy efficient systems for mobile applications; integration of microelectronics with hydraulic valves; mathematical modeling of components and systems; pneumatic systems; a variety of different pumps; dynamometry; hydraulic component and system noise; the problem of pump flow ripple; assessment of pump or motor performance. In addition, three of the papers are concerned with simulation, reflecting the industry-wide emphasis on performance and design.