Abstract: A multistage hydraulic machine including a main shaft, a main shaft sealing device, and plural runners mounted on the main shaft and containing water at different pressure levels. A top cover is mounted on the highest pressure stage runner and in the space therebetween there is provided a labyrinth-type intermediate sealing device which defines a first space between the cover, the intermediate sealing device, and the runner and a second space between the intermediate sealing device, the cover and the main shaft. Exhaust passages are provided in communication with the first and second spaces for exhausting compressed air during changeover from one operation to another. The second space exhaust passage is capable of communicating with a lower pressure runner. The intermediate sealing device and the exhaust passages prevent water at the pressure of the highest pressure runner from communicating with the main shaft sealing device.

Abstract: In a shaft sealing device for a hydraulic machine, a packing box is provided about a rotatable shaft of the hydraulic machine. A number of packings are encased in the packing box so that the sliding surfaces of the packings are urged against the movable shaft. Each of the packings is made of tetrafluoroethylene resin mixed with a filler, and molded under a pressure into a desired shape. The filler is selected from the group consisting of carbon powder, graphite powder, carbon fibers, glass fibers, and bronze powder, and combinations thereof.