Abstract: A hydraulic excavator is equipped with one or more downsizing scheme including at least one of: (i) a bubble removing device for removing bubbles in hydraulic fluid, (ii) a hydraulic tank including a main tank and a variable capacity tank arranged separately from each other, and (iii) a variable capacity tank or hydraulic tank which is fitted to the rear surface of the upper cover of the seat-side block. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a larger hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large hydraulic excavators, it is possible to significantly reduce the cost of the hydraulic excavator.

Abstract: A hydraulic excavator is equipped with one or more downsizing scheme including at least one of: (i) a bubble removing device for removing bubbles in hydraulic fluid, (ii) a hydraulic tank including a main tank and a variable capacity tank arranged separately from each other, and (iii) a variable capacity tank or hydraulic tank which is fitted to the rear surface of the upper cover of the seat-side block. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a larger hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large hydraulic excavators, it is possible to significantly reduce the cost of the hydraulic excavator.

Abstract: A fluid tank fluid is provided which includes a bubble removing device provided therein to remove bubbles from the fluid. The bubble removing device includes a cyclone chamber for generating a swirling current in the fluid flowing therethrough to separate bubbles from the fluid. At least one outflow port is provided through which the fluid from which the bubbles have been separated flows from the cyclone chamber. And an exhaust port is provided through which the bubbles separated from the fluid are driven from the cyclone chamber.

Abstract: A hydraulic excavator is equipped with one or more downsizing scheme including at least one of: (i) a bubble removing device for removing bubbles in hydraulic fluid, (ii) a hydraulic tank including a main tank and a variable capacity tank arranged separately from each other, and (iii) a variable capacity tank or hydraulic tank which is fitted to the rear surface of the upper cover of the seat-side block. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a larger hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large hydraulic excavators, it is possible to significantly reduce the cost of the hydraulic excavator.

Abstract: A hydraulic excavator is equipped with one or more than one downsizing scheme of arranging a bubble removing device for removing bubbles in hydraulic fluid, using a hydraulic tank including a main tank (51) and a variable capacity tank (52) arranged separately from each other and/or fitting the variable capacity tank (52) to the rear surface of the upper cover. Thus, the lateral section of the seat can be ultimately downsized to provide a large space around the seat. Then, unlike the prior art, a canopy or a cab of a large hydraulic excavator can be securely arranged on the upper swing body of a small hydraulic excavator. Since such large parts can be commonly used with large service vehicles, it is possible to significantly reduce the cost of the service vehicle.

Abstract: A cyclone type bubble removing device 30 is arranged in a hydraulic tank 1. Therefore, it is no longer necessary to secure a space for installing a bubble removing device 30 outside the tank 1 and hence the space dedicated to the hydraulic system can be reduced. Since the bubble removing device 30 is fitted to the inside of the hydraulic tank 1 in advance, it does not need to be installed separately somewhere in the hydraulic circuit so that the installing operation can be performed quickly. Additionally, the outflow ports 322 for causing hydraulic fluid from which bubbles have been removed to flow out and the exhaust port 333 for expelling bubbles are arranged separately so that it is possible to expose the exhaust port 333 to the drain space 127. Thus, if the hydraulic tank 1 is rocked to a large extent, the hydraulic fluid coming out of the outflow ports is not mixed with bubbles and hence bubbles can be eliminated reliably.