Patent ID: 6179553
Filing Date: 2001-01-30
Classification: F04D

Abstract:
A multiple stage centrifugal pump for liquids comprising:a plurality of rotors arranged on a drive shaft for rotation within a pump housing, the plurality of rotors including a rotor of a first stage of the pump, the rotor of the first stage of the pump being journalled on the drive shaft as a hollow shaft; anda mechanical converter for taking up mechanical power from the drive shaft to drive the hollow shaft at a fixed transmission ratio to produce a speed of rotation n.sub.2 of the hollow shaft, which is lower than the speed of rotation n.sub.1 of the drive shaft, thereby producing a lower NPSH.sub.R value for the multiple stage pump, the mechanical converter comprising a planetary transmission with a central gear connected to the drive shaft and a planetary carrier or an outer wreath connected to the hollow shaft.