| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic fluid composition which has power saving performance, high shear stability and excellent wear resistance, and is further excellent in thermal oxidation stability and storage stability which are basic performances as an industrial hydraulic fluid.SOLUTION: There is provided a hydraulic fluid composition which comprises: (a) a hydrocarbon base oil having a kinematic viscosity at 40°C of 28 to 51 mm/s; (b) 0.06 to 3 mass% of a polymethacrylate having a weight average molecular weight of 70000 to 200000; (c) 0.1 to 5 mass% of an olefin copolymer having a weight average molecular weight of 5000 to 100000; and (d) 0.2 to 2 mass% of a phosphorus anti-wear agent. |
