To prevent oil from leaking even under pressure having a high level by forming an inner surface of a lid for forming a pressure chamber in a recessed circular cone shape, eliminating one of a corner of the pressure chamber which contributes to leak oil, covering a rotating blade and a fixing blade with the lid, and connecting them to an external cylinder.

A main shaft 1 is installed on an external cylinder 2 through lids 3 arranged on both sides of the external cylinder 2. An annular hollow body is formed by the external cylinder and the lids 3, and is arranged in a pressure chamber by dividing at an equal clearance by a rotating blade with the main shaft 1 and a fixing blade 12 with the external cylinder 2. An outlet 61 for supplying and delivering oil is arranged in the pressure chamber. The lids 3 for composing a part of the pressure chamber is formed in such a constitution that an inner surface is formed in a recessed circular cone shape, the rotating blade 11 and the fixing blade 12 are covered, and they are connected to the external cylinder 2. The vertical cross sectional pressure chamber is formed in a barrel shape. A flat plate 31 of the rotating blade 11 and a round rod rubber 41 are arranged continuously along the external cylinder 2 and the lids 3, their both ends are little inserted into the main shaft 1, and a rubber 71 is filled therein.