Pneumohydraulic Servo Valves.

Discussion of the design, operation, and application of servovalves with pneumatic control and a hydraulic operation stage. The steady-state and dynamic parameters of some of these devices are reviewed. The results of an investigation of the frequency-response characteristic are presented. The behavior of servovalues in a control loop is outlined. It is shown that their application appears to be particularly suitable in cases of relatively slow processes and pneumatic control signals.