System for adjusting torsional frequency of a power train

A power train comprising:

• a torque producing power source including a rotating connecting flange;
• a torque driven power load including a rotating connecting flange;
• a load coupling having a first flange adapted to couple to the connecting flange of one of the torque producing power source and the torque driven power load;
• a second flange on the load coupling adapted to couple to the connecting flange of the other of the torque producing power source or the torque driven power load;
• an additional mass attachable to at least one of the connecting flanges or the load coupling wherein the additional mass is configured to shift a torsional natural frequency of the power train away from a torsional frequency corresponding to an operational condition of the power train and the additional mass is symmetrically distributed about a longitudinal axis of the power train, and
• trim masses configured to be sequentially added to the additional mass.