A power transmission system is disclosed for infinitely variable speed capability. The power transmission system includes a pair of power units, each configured to deliver a rotational torque to drive an output element. A transmission arrangement receives the rotational torques from the power units and delivers a resulting torque to the output element. The transmission arrangement includes a gear set coupling the one power unit to the output element to deliver torque through a mechanical meshing engagement that is continuously effected between the first power unit and the output element.