Abstract
In order to construct water hydraulic systems for environmental protection, we have developed a pollution-free water hydraulic pump and a water hydraulic servo valve. With a view to secure the same efficiency as oil hydraulic systems, we used a swash plate type axial piston pump, a spool type servo valve, and all parts are lubricated with water which is the hydraulic fluid. The system is made of ceramics, plastics, and so on. The water hydraulic pump has a mechanical efficiency of 94%, a volumetric efficiency of 86%, a power-to-weight ratio 1.0kW/kgf at the pressure of 21MPa, and a rotation speed of 1800min-1 The water hydraulic servo valve has leakage of under 760cm3/min and a response of 47Hz at a pressure of 21MPa. These components have the same performance as oil hydraulic system.
