To enhance reliability and workability by preventing a flowing out opening from sucking air, even when the liquid level of oil in an oil storing tank is inclined or lowered to a position where a filter member is exposed.
The upper cover 28 covering the periphery and the upper part of the filter member 23 is arranged in the tank body 17 of the operation oil tank 16 and the opening 28c where operating oil flows out to the filter member 23 is arranged in the position approximate to the bottom face plate 17F in the upper cover 28. Further, the air releasing valve 30 for releasing air in the upper cover 28 is arranged in the lid 28B of the upper cover 28. Consequently, the operating oil can be held in the upper cover 28 and the only the operating oil can be sucked to the flowing out opening 21 even when the liquid level of the operating oil is inclined or lowered by removing the air in the upper cover 28 by opening the air releasing valve 30 and thereby making the inside part a vacuum state when feeding the operating oil to the operating oil tank 16.
KISE TAKESHI
NAGASAWA TOKUJI
