An apparatus is provided and includes a hub, including opposing faces, a first sidewall fixed to the opposing faces to define a first interior and a second sidewall fixed to one of the opposing faces to define a second interior within the first interior, a first assembly, disposed within the second interior, to generate current from input mechanical energy, a second assembly, electrically coupled to the first assembly and disposed within the first interior, to generate mechanical energy to be transmitted to external mechanical elements from current associated with the current generated by the first assembly and first and second couplings, the first coupling being disposed to mechanically couple the first and second assemblies and the second coupling being disposed to mechanically couple the second assembly and the external mechanical elements.