Electrohydraulic servo valve

Servo valves can provide precise control of position, velocity, pressure, and force with good post-movement damping characteristics.

The EHSVs in use during the 1940s were characterized by poor accuracy and slow response times due to the inability to rapidly convert electrical signals into hydraulic flows.

Advancement of EHSVs took off in the 1950s, largely due to the adoption of permanent magnet torque motors as the first stage (as opposed to solenoids).

Single-stage servo valves suffer from limitations in flow capability and stability due to torque motor power requirements.

Typically, the valve will move the spool proportionnaly to an electrical signal that it receives, indirectly controlling flow rate.

These valves are suitable for electrohydraulic position, velocity, pressure or force control systems with extremely high dynamic response requirements.