SERVO VALVE

PURPOSE:To achieve a stabilized high-speed drive of a resonance load system by arranging a mechanical hydraulic type dynamic load damper between the servo valve and the actuator which drives the resonance load in a servo valve which converts an electric signal into a hydraulic signal. CONSTITUTION:So-called resonance load system is constructed by linking a body 203 having a large inertia with a shaft 127 which is formed as one body with a piston 112 of an actuator 110 via a spring 200 and further by linking a rigid body 202 with a cylinder 111 via a spring 201. Furthermore, a servo valve 101 which functions as a positioning control device, comprises a servo valve main body 102 and a mechanical hydraulic type dynamic load damper D arranged between the passages 107, 108 which in turn connects a pair of ports of the main body to the actuator 110. The damper D consists of an isolation piston section 210 and a circuit in series of a bypass valve 220. Thus, a stabilized high-speed drive of the resonance load is achieved and the static accuracy at rest is ensured.