Abstract: The appliance employs two rotatable head structures, each of which carries for rotation therewith at least one spray nozzle for depositing cleaning fluid and at least one vacuum nozzle for extracting cleaning fluid and debris. The relative positioning of the two head structures is such that the vacuum patterns of the vacuum nozzles of the two structures overlap. In a preferred mode, each head structure carries a plurality of spray nozzles and a like number of vacuum nozzles. The angular spacing between the spray nozzles and the vacuum nozzles on each head may be adjusted. A hydraulic motor powered by the pressurized cleaning fluid may be employed to drive the rotatable head structures.