Abstract: A device for controlling two output elements pivotally mounted with respect to two stationary elements is provided with two coaxial rectilinear double action pressure fluid jacks. The two stationary elements are respectively secured to the ends of a stationary outer longitudinal elongated member while the two pivoting elements are respectively secured to the ends of pivotal inner longitudinal elongated member coaxially arranged in said outer member. The jacks are of annular configuration and formed between the outer and inner aforesaid members with a common median bottom and annularly slotted cylinder-heads remote from each other. The tubular piston rod of each jack extends in leak-tight manner through the annularly slotted cylinder-head and is angularly positioned on the one hand, with respect to the corresponding stationary element by a first set of guides and on the other hand with respect to the corresponding pivoting element by a second set of guides forming an angle relative to the first set of guides.

Abstract: Each fan-blade carries a bevel-pinion in mesh with two bevel ring-gears which are driven in rotation in opposite directions by means of two coaxial cylindrical tubular members. Carriages are mounted for axial motion within the space formed between the two tubular members; balls are fitted in helical grooves formed at opposite angles of slope in the internal and external cylindrical faces of the carriages and in corresponding helical grooves formed in the adjacent faces of the tubular members so as to form a ball-race. The moving member of at least one axial hydraulic jack constituting a motor is coupled to the carriages and the stationary member is coupled to the fan-shaft.