| 摘要 |
A rotary type pumping machine such as a pump turbine in a pumped storage hydro-electric plant, wherein, when the pumping operation of the runner of the machine is started, compressed air is introduced into the runner chamber to depress the water surface in the runner chamber to facilitate the start up of the runner and, when the runner is accelerated to a predetermined speed, the air in the runner chamber is discharged through an air discharge valve to commence the pumping operation. Water pressure available in the water passageway on upper reservoir side of the runner chamber is applied to the valve closing mechanism of the air discharge valve. The valve opening force exerted by a valve operating mechanism and acting on the valve opening mechanism of the air discharge valve is selected to be greater than the valve closing force generated by the water pressure applied to the valve closing mechanism of the air discharge valve. Therefore, the air discharge valve is closed without fail even when the valve operating force exerted by the valve operating mechanism is lost.
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