| 摘要 |
PURPOSE:To enable to decrease the thrust acted to a hydraulic shaft, by introducing water pressure in a casing into a side pressure chamber at the stage where the pressure is lowermost, and forming multi-stage seals in the lowermost pressure state side pressure chamber at the sections thereof located on the inner and outer circumferential side of a runner. CONSTITUTION:Multi-stage seals 17, 18 are formed on the outer and inner circumfernetial sides of a side pressure chamber 10a, and control is executed by a control valve 16 such that the differential pressure detected by detectors 19, 20 disposed respectively on the side of a high-pressure stage and a low-pressure stage lies within a prescribed range. With such an arrangement, even if water pressure in a casing 6 is introduced as high-pressure water into the side pressure chamber 10a at the low-pressure stage, leakage of water is not caused so much by the function of the multi-stage seals 17, 18. Therefore, it is enabled to decrease the thrust force acted to a hydraulic shaft 21. |
