Which statement correctly differentiates direct-acting from pilot-operated hydraulic valves?

• A. Direct-acting valves are shifted by pressure on the main valve; pilot-operated valves use a smaller pilot signal to shift the main valve, enabling higher force with lower control pressure.
• B. Direct-acting valves use a pilot signal to shift the main valve; pilot-operated valves are shifted by the main pressure.
• C. Both valve types are shifted by the main supply pressure with no pilot signal.
• D. Pilot-operated valves have no control pressure requirement.

Answer: (A)

The main idea is how the valve is actuated. A direct-acting hydraulic valve is moved by the pressure acting directly on the main valve spool. It relies on the control pressure itself to shift the main valve, so the required control pressure tends to be higher to overcome springs and seals.

A pilot-operated valve uses a small pilot signal to move a separate pilot valve. That pilot valve then uses system pressure to shift the main valve, so a much smaller control pressure is needed while still delivering a large actuation force on the main valve. This setup lets the main valve handle higher flows and forces without needing a high control pressure.

That’s why this option is correct: direct-acting valves are shifted by pressure on the main valve, while pilot-operated valves use a smaller pilot signal to move the main valve, enabling higher force with lower control pressure. The other statements misstate how the actuation works or claim there’s no control pressure needed.