| 摘要 |
<p>PURPOSE:To restrict the evaporation of water by employing a subtank of a capacity smaller than that of a main tank and open to the atmosphere, and disposed at a position so that the oil level of the subtank is located above the uppermost portion of the main tank. CONSTITUTION:A main tank 10 provided with an oil supply port 12, a suction port 14, return ports 1, 18 is filled with working oil 22 containing water. An air vent hole 20 is formed in the ceiling of an air trap 24 provided at the topmost portion of the tank 10. A subtank 26 is disposed with its bottom located above the top surface of an air trap 24 formed at the topmost portion of the main tank 10. The capacity of the subtank 26 is smaller than that of the main tank 10, is a minimum required amount necessary for driving an actuator 30, and capable of absorbing the amount which amount be accommodated in the main tank 10 including the amount in pipings 48, 50, 60, 64 and others, and the expansion amount due to the temperature rise in working oil 22a containing water. Thus the evaporation of water is restricted, and work efficiency is improved with simplified structure and with reduced number of water supply.</p> |
