Adjustable propeller

A controllable pitch propeller, particularly for a boat drive, comprising a drive shaft, a rotating hub driven by said shaft, said hub including an external housing having propeller blades mounted thereon and an inner bearing sleeve receiving said shaft and connected to said external housing by radial webs so that exhaust gas channels are formed between said external housing and said inner bearing sleeve;

• and adjustment means provided in said hub for said propeller blades, said adjustment means including a plurality of adjusting bars guided in said outer housing and an adjustment ring connected to said bars, said adjustment ring being formed as a single ring-shaped piston, said external housing having a cylindrical chamber in which said piston is reciprocally movable in an axial direction thereof, said cylindrical chamber having two working chambers at two sides of said piston, said external housing further having bores for supplying hydraulic fluid to said working chambers, one of said bores opening into an end of one of said working chambers, and a tube being provided to connect one of said bores to another of said working chambers to supply said another chamber with hydraulic fluid, said tube being guided in a sealed manner through a corresponding passage of said cylinder piston.