Patent ID: 8591136

Claim:
A non-rotating universal joint for a helicopter drive unit, the non-rotating universal joint comprising: a spider defined by a ring, which extends about a longitudinal axis and comprises four connecting portions spaced 90° apart and each having a respective first through hole radially extending therethrough with respect to said longitudinal axis; two annular connecting members disposed on opposing sides of said ring about said longitudinal axis, each connecting member comprising respective pairs of arms; the arms of each connecting member diametrically opposing each other, being offset 90° with respect to the arms of the other connecting member, and comprising respective forks; each of said forks comprising two opposing axially extending fingers defining between them a tangential slot engaged by a corresponding said connecting portion; and the fingers of each said fork having respective aligned second through holes coaxial with the first hole in the corresponding connecting portion; four connecting bolt devices, each for fixing a respective said fork to the corresponding said connecting portion, and each comprising: a screw with a shank extending through a corresponding set of aligned said first and second holes; a nut screwed to a threaded end portion of said shank; a respective pair of annular bushings fitted to an inlet and outlet respectively of each said first hole; and a spacer interposed between each of said bushings and a corresponding said finger; wherein each said bushing comprises a first axially extending damping portion, defined by a layer of damping material, extending through a corresponding said first hole and interposed between said shank of said screw and said connecting portion of said ring, and a second radially extending damping portion, joined to said first damping portion and defined by a layer of damping material, interposed between said connecting portion of said ring and a respective said finger of a corresponding said fork; wherein each said bushing comprises two rigid members coaxial with each other and fixed, on opposite sides, to said first and second damping portions; wherein each said rigid member comprises an axially extending portion engaging a respective one of said shank of said screw and said connecting portion of said ring, and a second radially extending portion, joined to said first portion, engaging a respective one of said connecting portion of said ring and a corresponding said spacer.