What primarily shifts the main stage spool in a solenoid controlled, pilot operated directional control valve?

In a solenoid-controlled, pilot-operated directional control valve, the main stage spool is primarily shifted by hydraulic pressure. In this type of valve, the solenoid serves to energize a pilot signal that opens a pilot passage, allowing hydraulic fluid to flow and create pressure on one side of the main spool. This hydraulic pressure acts directly on the spool, causing it to move to its new position.

While solenoids play an integral role in initiating the operation of the valve, their function is to create a hydraulic signal rather than directly shifting the main spool. The hydraulic pressure generated from this signal is what ultimately shifts the spool to direct the flow of fluid through the valve, changing its operational state.

Levers can also be a means to operate some kinds of valves, but in the context of a solenoid-controlled directional valve, the primary action is generated through hydraulic pressure resulting from the pilot operation. Additionally, the maximum pressure relief valve setting is related to system limits and safety features, but it does not directly influence the movement of the valve spool in a manner similar to hydraulic pressure.