PUMP

To rotationally drive a double inversion type impeller without using a reduction gear or a spindle of a double structure and to simplify management or installations.SOLUTION: A pump comprises: a first water pressure motor 3A to which a first impeller 4A is attached and which rotationally drives this impeller; a second water pressure motor 3B to which a second impeller 4B is attached and which rotationally drives this impeller; a casing 2 including a water pump port 2a through which raw water is pumped up, in an end; a circulation water passage 5 for supplying circulation water to the first water pressure motor and the second water pressure motor; and a circulation water supply section 6 which is installed outside of the casing and supplies the circulation water pressurized via the circulation water passage to the first water pressure motor and the second water pressure motor. The first impeller and the second impeller include blades 4a which are disposed on two front and rear stages on mutually the same axis and of which the twist directions are inverse to each other, and the first water pressure motor and the second water pressure motor rotationally drive the first impeller and the second impeller in mutually inverse directions.SELECTED DRAWING: Figure 1 【課題】 減速機や二重構造の主軸を用いずに二重反転式の羽根車を回転駆動できると共に、管理や設備を簡易化すること。【解決手段】 第１の羽根車４Ａが取り付けられこれを回転駆動する第１の水圧モータ３Ａと、第２の羽根車４Ｂが取り付けられこれを回転駆動する第２の水圧モータ３Ｂと、原水を吸い上げる吸水口２ａを端部に有したケーシング２と、第１の水圧モータ及び第２の水圧モータに循環水を送る循環水流路５と、ケーシングの外部に設置され循環水流路を介して加圧した循環水を第１の水圧モータ及び第２の水圧モータに送る循環水供給部６とを備え、第１の羽根車と第２の羽根車とが、互いに同一軸心上の前後２段に配設されていると共に捻れ方向が互いに逆の羽根４ａを有し、第１の水圧モータと第２の水圧モータとが、第１の羽根車と第２の羽根車とを互いに逆方向に回転駆動する。【選択図】 図１