A load coupling device for a power train including: a rotatable shaft; a first flange on a first end of the shaft, wherein the first flange is adapted to couple to a first rotating shaft of a torque producing turbine or a torque driven electrical generator; a second flange on an opposite end of the shaft, wherein the shaft is adapted to couple to a second rotating shaft of the other of the turbine and the generator, and an annular ring extending radially outward from the first flange, wherein the mass of the annular ring is selected to shift a torsional natural frequency of the power train away from an operational condition of the power train. Trim masses may be added to make fine adjustments to the torsional natural frequency of the power train.