Blade pitch control mechanism for a helicopter

Claim 1

FOR USE IN A HELICOPTER PROVIDED WITH A LIFTING ROTOR HAVING A GENERALLY VERTICAL DRIVE SHAFT AND A PLURALITY OF GENERALLY RADIAL BLADES CONNECTED WITH SAID DRIVE SHAFT AND MOVABLE ABOUT SPANWISE PITCH CHANGING AXES, THE COMBINATION COMPRISING AN AZIMUTH ASSEMBLY FOR CONTROLLING THE PITCHES OF SAID BLADES AND INCLUDING A NONROTATABLE AZIMUTH RING AND A SWASH PLATE ROTATABLE ABOUT AN AXIS FIXED RELATIVE TO THE RING AND NORMALLY COINCIDENT WITH THE ROTOR AXIS, A FIRST VERTICAL LINK CONNECTED WITH THE CENTER OF SAID SWASH PLATE FOR MOVING SAID AZIMUTH ASSEMBLY UPWARDLY AND DOWNWARDLY ALONG SIDE ROTOR AXIS, A SECOND VERTICAL LINK CONNECTED TO SAID NONROTATABLE RING AND LOCATED IN A TRANSVERSE PLANE PASSING THROUGH SAID ROTOR AXIS FOR TILTING SAID AZIMUTH ASSEMBLY ABOUT A LONGITUDINAL HORIZONTAL AXIS, A THIRD VERTICAL LINK CONNECTED TO SAID NONROTATABLE RING AND LOCATED IN A LONGITUDINAL PLANE PASSING THROUGH SAID ROTOR AXIS FOR TILTING SAID AZIMUTH ASSEMBLY ABOUT A TRANSVERSE HORIZONTAL AXIS, FIRST AND SECOND AND THIRD BELL CRANKS LOCATED BELOW SAID AZIMUTH MECHANISM AND EACH OF WHICH BELL CRANKS IS SUPPORTED FOR PIVOTAL MOVEMENT ABOUT A HORIZONTAL AXIS EXTENDING APPROXIMATELY 45* TO SAID LONGITUDINAL PLANE, SAID BELL CRANKS BEING ASSOCIATED RESPECTIVELY WITH SAID FIRST AND SECOND AND THIRD VERTICAL LINKS AND EACH OF SAID BELL CRANKS INCLUDING A GENERALLY HORIZONTAL ARM PIVOTALLY CONNECTED WITH THE LOWER END OF THE ASSOCIATED VERTICAL LINK AND ALSO INCLUDING A GENERALLY VERTICAL ARM, AND PILOT OPERABLE MEANS FOR MOVING SAID BELL CRANKS ABOUT THEIR HORIZONTAL PIVOT AXES WHICH MEANS INCLUDES FIRST AND SECOND AND THIRD GENERALLY HORIZONTAL LINKS PIVOTALLY CONNECTED RESPECTIVELY TO SAID VERTICAL ARMS OF SAID FIRST AND SECOND AND THIRD BELL CRANKS AND WHICH LINKS EXTEND GENERALLY PERPENDICULAR TO SAID HORIZONTAL PIVOT AXES OF SAID BELL CRANKS.