Control system for yaw control rotors of helicopters

Claim 1

IN A HELICOPTER OF THE TYPE HAVING A REARWARD FUSELARGE EXTENSION MOUNTING A TAIL ROTOR GEARBOX, A TAIL ROTOR SYSTEM COMPRISING A LONGITUDINAL SHAFT EXTENDING REARWARD ALONG THE FUSELAGE EXTENSION AND TERMINATING IN THE GEARBOX, A ROTOR SHAFT GEARED TO SAID LONGITUDINAL INPUT SHAFT WITHIN THE GEARBOX, A HUB MOUNTED ON SAID ROTOR SHAFT, A BLADE MOUNTED ON SAID HUB FOR PITCH-CHANGE MOVEMENT, IN COMBINATION WITH PILOT OPERABLE CONTROL MEANS, BELL CRANK MEANS PIVOTALLY MOUNTED ABOVE AND BELOW THE GEARBOX WITH ITS PIVOTAL AXIS INTERSECTING THE AXIS OF SAID INPUT SHAFT, SAID BELL CRANK MEANS HAVING PORTIONS COMPLETELY ENCIRCLING THE GEARBOX AND ENGAGED SIDEWARDLY THEREOF BY SAID PILOT OPERABLE MEANS AND HAVING ARMS EXTENDING ABOVE AND BELOW SAID TAIL ROTOR SHAFT AND MOVABLE IN AN ARC TO WHICH A PLANE THROUGH THE AXIS OF THE ROTOR SHAFT IS TANGENT, SLEEVE MEANS MOUNTED ON SAID TAIL ROTOR SHAFT FOR ROTATION THEREWITH AND AXIAL MOVEMENT THEREALONG, YOKE MEANS INCLUDING AN ANNULAR RING PORTION AND ARM PORTIONS EXTENDING THEREFROM ABOVE AND BELOW THE TIAL ROTOR SHAFT TO ENGAGE SAID ARMS OF SAID BELL CRANK MEANS, SAID RING PORTION MOUNTING AN ANNULAR SPHERICAL BEARING WHICH ENGAGES SAID SLEEVE MEANS, AND MEANS ENGAGING SAID SLEEVE MEANS AND SAID BLADE FOR TRANSMITTING PITCH-CHANGE MOVEMENTS TO SAID BLADE.