Direct-acting and pilot-operated valves solve the same routing task in different ways. The choice affects electrical demand, available flow, start-up behavior and what happens when pilot pressure disappears.
Understand how the main spool moves
A direct-acting design moves the working spool directly through its actuator. A pilot-operated design uses a smaller control stage to direct hydraulic pressure that shifts the main stage. This can support larger main flows, but adds conditions that the circuit must provide.
Check low-pressure operating states
A circuit may have adequate pressure under load but insufficient pilot pressure during unloading or start-up. Ask for the main stage's minimum and maximum pilot pressure, its pilot supply arrangement and its permitted drain pressure. Do not infer these from the system relief setting.
Compare failure and service behavior
Document the de-energized state, spring arrangement and any manual override. A control signal alone does not establish that the main spool has moved. For replacement work, identify both stages and their settings; matching only the small pilot valve can leave the main assembly incompatible.
Practical checklist
- Provide main flow and lowest available pilot pressure.
- Confirm internal or external pilot supply and drain.
- Review start-up, shutdown and power-loss states.
Discuss your application
Explore related hydraulic products, or send JIUDING your model code and application details. Include the circuit drawing and the operating conditions relevant to the checks above so the required configuration can be reviewed.
Cover image: AI-generated editorial illustration, not a model-specific product drawing or a photograph of a JIUDING facility.
