Abstract: A load apparatus generally comprises a load that converts mechanical rotational energy to electrical energy. A rotor assembly is coupled to the load and includes a rotor shaft having at least one end portion with at least one extension portion that extends radially outwardly from a surface of the rotor shaft end portion. A coupling shaft couples to the rotor shaft, wherein the coupling shaft includes a cylindrical main body portion. The coupling shaft also includes at least one end portion that extends from the main body portion, wherein the coupling shaft end portion couples to the rotor shaft end portion. The coupling shaft end portion includes an exterior surface, an opposing interior surface, and at least one slot that extends from the interior surface and through the exterior surface, wherein the slot receives the extension portion therein such that the extension portion extends radially outwardly from the exterior surface.