A driveshaft assembly for a downhole motor including a driveshaft having a longitudinal axis, first and second ends, and a convex spherical bearing surface disposed at the first end configured to transfer axial loads. The assembly also includes a connection lug disposed at the driveshaft first end, extending circumferentially between first and second ends, and including a recess in the first end of the lug, the recess comprising a concave cylindrical surface concentrically disposed about a pivot axis oriented orthogonal to the longitudinal axis. The assembly also includes a torque transfer key disposed within the recess and having a central axis radially spaced from the pivot axis, a convex cylindrical surface concentrically disposed about the pivot axis, and a planar surface. The convex cylindrical surface of the key slidingly engages the concave cylindrical surface of the recess; and the pivot axis intersects the key.

Claims data not available