🔍 Key Concepts

• Controllable-pitch propeller (CPP) hub mechanism – how linear (axial) motion is converted into rotation of each blade • Relationship between the hydraulic piston / crosshead and the parts actually located inside the hub body such as the sliding block, crankpin ring, and internal gearing • Which part in the hub directly connects to the blade root/crank pin to twist the blade when it moves axially

💭 Think About

• Trace the force path starting from the hydraulic piston in the tailshaft: which part moves axially first, and which component inside the hub is the next to move? • Look at how the crankpin ring and blade roots are drawn: do they rotate in place, or also move axially? Which labeled piece is clearly designed to slide back and forth? • Ask yourself: among the listed parts, which one would best serve as the sliding interface that converts push–pull motion into rotation of the blade via an eccentric pin or crank?

✅ Before You Answer

• On the illustration, confirm which component is explicitly drawn on a sliding track or guide and is aligned with the axis of the tailshaft. • Verify which part is in direct contact with the crankpin / blade root mechanism and therefore can twist the blade when it moves. • Make sure you distinguish between the part that only rotates (like a ring gear or crankpin ring) and the one that actually moves axially along the hub’s length.