There (indeed) are single acting and double acting blade fineness adjustment systems. In the **single acting** design, the hub counterweight is set to **use centrifugal force to move blade to coarse**. Oil pressure, in the form of a hydraulic piston, is used to move the blade to fine. In a double acting system, oil pistons move the blade both ways. Confusion may arise in the statement "moves the blade to a lower angle", as for **feathering**: the "low blade angle" is *to the wind*, not to the axis of rotation (very coarse). For the **propeller blade itself**, it is entirely possible that more mass may be ahead of the pivot point **which would cause a centrifugal twist force towards fine**. >"Aerodynamic forces try to move the blade to a coarse pitch" Yes, and this is counterbalanced by the *blade center of gravity* trying to move to fine from centrifugal force. This helps balance forces on the *blade shaft*. But we must consider **all components of the rotating plane**, including the hub and attachments. In order to be able to "feather" the prop in the event of engine failure, a counterweight is added to the hub to fully coarsen the prop pitch.