What components in servo valves regulate the position of the spool?

In a servo valve, the position of the spool is regulated through the interaction of both the flapper nozzle and the jet pipe.

The flapper nozzle creates a controlled flow of fluid based on the position of the flapper, which is influenced by the input signal. This flow is directed through the nozzle, causing a pressure difference that moves the spool. The flapper adjusts this flow and pressure difference to control the direction and amount of hydraulic fluid that passes through the valve.

Simultaneously, the jet pipe captures the fluid flow from the flapper nozzle and directs it to the appropriate chambers of the valve, further ensuring precise control over the spool's position. The design of both of these components allows them to work in unison to achieve accurate positioning and regulation of the hydraulic system, making their combined function essential for optimal performance of the servo valve.

Thus, the correct answer is that both the flapper nozzle and the jet pipe work together to regulate the position of the spool in a servo valve.