| 摘要 |
The counterrotatable bladed rotor assembly is driveable by a rotatable shaft 17 and comprises: - a leading propeller 12; - a trailing propeller 13; - an epicyclic gearbox 14 located between the leading and trailing propellers; - a first fluid pressure operable actuator 34 to vary the pitch of the blades of the leading propeller 12; and - a second fluid pressure operable actuator 35 to vary the pitch of the blades of the trailing propeller 13. The actuators 34, 35 are connected to a source of fluid 101, 100 under pressure via an overspeed governor 102, electrohydraulic valves 110, 111, passages 63, 64 follow-up valve means 50, 62, 65, 66, and passages in actuator tubes 54, 55. An electronic control unit 115 controls valves 111, 110 in response to a desired signal representative of either pitch or speed and set by a pilot operated control 60 or 52, and feed back signals derived from either speed sensors 108, 109 or pitch sensors 116, 117. By adjusting a tube 50 of the follow-up valve means, the pilot can vary the range within which the propeller pitches can vary. A dump valve 112 and non-return valves 106, 107 are also provided. <IMAGE>
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