A Vickers servo valve is a type of control valve that is used to control the flow of fluid in industrial systems such as hydraulic and pneumatic systems. 

It is a type of servo valve, which means that it uses feedback to control the flow of fluid through the valve. 

The Vickers servo valve uses a spool that is controlled by an actuator, which is in turn controlled by an electronic signal. 

The electronic signal is used to position the spool in the valve body, which controls the flow of fluid through the valve. 

Vickers servo valves are known for their high precision and accuracy, and are commonly used in applications such as manufacturing, aerospace, and robotics.