Servo Directional Control Valves
Very accurately control the flow into the A or B lines depending on the electrical control signal. Generally used in high performance closed loop control systems.
Servo valves require a significant pressure drop across the valve to accurately control the flow, say 30 bar, and stiff, high natural frequency, systems to operate correctly.
Require very good fluid cleanliness
Spool center positions bias may vary.
Valve response times may vary.