Patent ID: 8376701

Claim:
A multi-stage centrifugal pump assembly comprising: a motor housing ( 2 ) having a rotatably mounted motor shaft ( 7 ) which carries a rotor ( 6 ); a pump housing ( 4 ) having a rotatably mounted pump shaft ( 9 ), on which at least two impellers ( 10 ) are arranged in a rotationally fixed manner, wherein the pump housing ( 4 ) is fixedly connected to the motor housing ( 2 ), and the motor shaft ( 7 ) is fixedly connected to the pump shaft ( 9 ), and wherein a motor-side end of the pump shaft ( 9 ) is fixed within a pocket hole ( 24 ) at a pump-side end of the motor shaft ( 7 ); and a bearing ( 11 ) for mounting the motor shaft ( 7 ) and the pump shaft ( 9 ), the bearing being arranged in a bearing carrier ( 5 ) provided in a connection region of the motor housing and the pump housing, wherein the pump shaft ( 9 ) comprises an outer thread ( 27 ) on or near to the motor-side end of the pump shaft, the outer thread meshing into an inner thread ( 26 ) of the pocket hole ( 24 ), a first fit section ( 31 ) of the motor shaft ( 7 ) is spaced from the outer thread in a direction toward the impellers, and, a different second fit section ( 34 ) of the motor shaft ( 7 ) is spaced from the first fit section and spaced from the outer thread in a direction toward the impellers, the first fit section and the second fit section are within the pocket hole ( 24 ).