Controllable pitch propeller system

Claim 1

Controllable pitch propeller mechanism comprising: a hollow, rotatable shaft; a propeller hub mounted on one end of the shaft for rotation therewith; a plurality of elongated propeller blades mounted on said hub and extending radially outwardly therefrom, said blades being rotatable about their longitudinal axes relative to said hub; a first piston and cylinder assembly disposed within said shaft adjacent said hub, said first assembly including a cylinder extending longitudinally of the shaft and having a pair of longitudinally spaced fluid ports communicating with the interior thereof, and a piston disposed between said ports for movement longitudinally of the cylinder, said piston being operably connected to said blades for rotating the latter about their longitudinal axes during said movement of the piston; a pressure fluid supply system including a source of presSurized fluid and a fluid return; valve means operably intercommunicating said fluid supply system and the ports of the piston and cylinder assembly, said valve means being operable for alternatively connecting either of said ports with said source of pressurized fluid while simultaneously connecting the other of said ports with said fluid return, there being a fluid passageway extending between each of said ports and said valve; a slide valve assemblage comprising a second cylinder and piston assembly disposed in the propeller shaft, said second assembly comprising a piston member movable axially of said shaft between two extreme positions, said member being provided with a hollow cylindrical skirt having an open end extending toward and opening into one of said passageways, said skirt being disposed, when said piston member is in one of its extreme positions, to block said one passageway between said valve means and the hollow space within said skirt with the latter remaining in fluid communication with said passageway and its port, the cylinder of the second assembly being provided with an inlet communicating with the cylinder space on the side of the piston member remote from said passageway, said inlet being connectable to a second source of pressurized fluid, said second assembly including passage defining means disposed for intercommunicating said cylinder space with said hollow space of the piston member when the latter is in said one extreme position.