In the oil hydraulic system, the internal oil flow in the controlled elements should be analyzed by considering the flow pattern in order to improve the controllability of the system.
In previous paper, the boundary element method was applied to these problems, and the velocity profiles in the hydraulic controlled valve were examined.
In this paper, the velocity profiles in the spool valves of the various shapes were simulated by the boundary element method, and by using the obtained velocity vectors, these steady flow axial forces were calculated and compared. The most suitable shape of the spool valve, which can be improved the controllability of the hydraulic controlled valve of a spool type, was presented.