Abstract: The invention relates to a control apparatus for a hydraulic variable-pitch propeller (12) of an aircraft, land vehicle or water vehicle, comprising: a hydraulic oil feed line (24); a control line (16) which can be connected to the variable-pitch propeller (12); a pressure generating device (73) which is connected to the hydraulic oil feed line (24) and provides hydraulic oil with a basic pressure; a servo valve (78) which is arranged downstream of the pressure generating device (73), the input pressure to which servo valve is the basic pressure and the output pressure from which servo valve during normal operation defines a control pressure in the control line (16) and which servo valve is connected to a controller (28) which delivers a control signal for changing the control pressure; and pressure reducing means which are arranged downstream of the servo valve (78) and upstream of the control line (16), which are mechanically actuated and which, in the event of a failure of the servo valve (78), change t

Abstract: Proposed is a redundant hydraulically controlled variable pitch propeller for an air, land or water craft, comprising at least two propeller blades (14) mounted in a propeller hub (12) for variable pitch control by means of a hydraulically powered piston assembly (18). In accordance with the invention the piston assembly (18) comprises two mechanically interconnected servo pistons (20, 22) each assigned an independent hydraulic circuit.

Abstract: Proposed is a hydraulically controlled variable pitch propeller system for air, land or water craft, comprising an engine, an engine controller, a rotating propeller featuring at least two propeller blades (16), for the pitch control of which a propeller governor (30) is provided connecting the propeller (10) via at least one hydraulic line and comprising a governor body (32) housing a control spool (46) the position of which is determined by the cooperation of flyweights (40) rotating by means of the engine and a variably biased governor spring (48) supported by the control spool (46). In accordance with the invention, the propeller governor (30) comprises an electric motor (58) which sets the preload of the governor spring (48) for the desired rpm and is electrically connected to the engine controller.

Abstract: Proposed is a hydraulically controlled variable pitch propeller system for air, land or water craft, comprising an engine, an engine controller, a rotating propeller featuring at least two propeller blades (16), for the pitch control of which a propeller governor (30) is provided connecting the propeller (10) via at least one hydraulic line and comprising a governor body (32) housing a control spool (46) the position of which is determined by the cooperation of flyweights (40) rotating by means of the engine and a variably biased governor spring (48) supported by the control spool (46). In accordance with the invention, the propeller governor (30) comprises an electric motor (58) which sets the preload of the governor spring (48) for the desired rpm and is electrically connected to the engine controller.

Abstract: Proposed is a redundant hydraulically controlled variable pitch propeller for an air, land or water craft, comprising at least two propeller blades (14) mounted in a propeller hub (12) for variable pitch control by means of a hydraulically powered piston assembly (18). In accordance with the invention the piston assembly (18) comprises two mechanically interconnected servo pistons (20, 22) each assigned an independent hydraulic circuit.