F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
F04D—NON-POSITIVE-DISPLACEMENT PUMPS
F04D25/00—Pumping installations or systems
F04D25/02—Units comprising pumps and their driving means
F04D25/08—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
F04D25/10—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation the unit having provisions for automatically changing direction of output air
F04D25/105—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation the unit having provisions for automatically changing direction of output air by changing rotor axis direction, e.g. oscillating fans