The direction in which the control oil servo...

Question 1 of 270705eccef9cbacbc34ba4d45a8c

The direction in which the control oil servo valve opens and directs control oil to the oil distribution (OD) box piston in a CPP system is determined by the command _________. See illustration GS-0170.

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Question 1 of 27070

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🔍 Key Concepts

• Closed-loop control feedback in a controllable-pitch propeller (CPP) system • How an electrohydraulic servo valve responds to an electrical command signal • Difference between command signal and feedback signal in determining direction of motion

💭 Think About

• Looking at GS-0170, trace the path from the bridge/bridge control to the electrohydraulic servo valve. What electrical characteristic changes when you move the pitch lever from ahead to astern? • In a closed-loop system, does the feedback usually decide the direction of motion, or does it mainly tell the system how far off the commanded position it is? • In an electrohydraulic servo, what aspect of the incoming signal makes the internal spool shift to one side or the other, thus selecting which side of the OD box piston gets oil?

✅ Before You Answer

• Verify on the diagram which signal is labeled as the command input to the servo amplifier/servo valve, and which is labeled as feedback from the follow‑up device or OD box. • Confirm whether timing (when the signal occurs) or polarity (its positive/negative direction) is what actually makes the servo valve port oil to one side or the other. • Make sure you distinguish between the signal that initiates direction of movement and the signal that simply reports actual position back to the controller.