A mechanical output generating assembly including housing having a fluid filled interior and defining a passageway through which travels a buoyant article. A reload mechanism is secured to the housing for successively introducing a plurality of buoyant article into a bottom feed location associated with the housing. The buoyant articles exert a lift generating force to drive a power take off component incorporated into the housing. A re-supply mechanism is provided for transferring buoyant articles from an upper exit location of the housing to the reload mechanism for subsequent re-introduction into the housing.