Feathering controllable pitch propeller

Claim 1

A controllable-pitch marine propeller having blades carried by a hub and having a hydraulic actuator housed in the hub and coupled to the blades for altering the blade pitch angle in both directions, and a servo control system for controlling the actuator to adjust the blade pitch angle, the control system having a blade position feedback loop by which the system operates with positional feedback over the range of pitch angle between astern and fullahead pitch angles, and means to render the feedback loop inoperative in response to a demand signal for blade feathering whereby the actuator then moves the blades into the feathering position without feedback action in response to the said demand signal, said feedback loop including a mechanical link constituted by a fluid supply pipe longitudinally-movably mounted in a bore in the propeller shaft, to supply pressure fluid to the actuator, the oil supply pipe having an end stop arranged to engage a fixed abutment to render the feedback loop inoperative when the actuator adjusts the blade pitch angle beyond the full-ahead position.