They are called 'Demand Pumps' on the 747-400. Systems 1 and 4 have air driven demand pumps and systems 2 and 3 have electric motor driven demand pumps. The demand pump supplements the EDP during high demand conditions. All four demand pumps are selected to 'Auto' throughout the flight unless a QRH drill has dictated otherwise. This is standard Boeing procedure and applies to all airlines and all engine types.
Airclues