What does a dashed line in a pneumatic schematic represent?

• A. Return line
• B. Supply line
• C. Pilot line
• D. Signal line

Answer: (C)

In pneumatic schematics, the dashed line represents a pilot (control) line. This narrow, non-structural path carries a small amount of compressed air used to control or pilot a valve rather than deliver the main work flow. The work air paths—supply to actuators or valves and exhaust paths—are drawn as solid lines, since they carry the primary air that powers movement. The pilot line connects to the pilot port of a component, providing the signal that shifts its position. So the dashed line signals a control function, not the main air supply to the actuator.