Articulated hub for helicopter rotor

Claim 2

A hollow unit-construction mast-hub assembly for pivotally supporting at its top a helicopter rotor, comprising, in combination, a plurality of hollow cylindrical arms having open extremities; sleeves pivotally and slidably mounted on said extremities, each of said sleeves being adapted to support a rotor blade; a blade attachment clevis connected to each said sleeve, a flapping and lead-lag hinge device being interposed between each of said sleeves and each of said blade attachment clevises; and torsionally flexible tie means being positioned in each of said arms, said tie means being interposed between each of said sleeves and a central corepiece located in said mast-hub so as to be adapted to distribute and balance centrifugal forces developed by the rotor blades.

Claim 3

An assembly as claimed in claim 1, including a clevis mounting a lead-lag pivot being supported at the external extremity of each of said sleeves; a flapping pivot traversing said lead-lag pivot at right angles to its axis, the flapping pivot having two ends for supporting one of said blade attachment clevises, said lead-lag pivot mounting clevis including an internal radially slidable catch bearing against an externally positioned radially acting return spring, said catch being adapted to mechanically cooperate with an abutment formed on said lead-lag pivot, whereby said catch retracts through a radial externally oriented sliding motion causing deformation of said spring in response to centrifugal force, thereby fAcilitating angular deflection of said blade attachment clevis and of the rotor blade associated therewith, for upward and downward motion of the later.