| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic oil composition high in sludge resistance and excellent in frictional characteristic. SOLUTION: The composition is based on one or more oils selected from the group consisting of mineral oil, fatty oil, and synthetic oil, and contains (A) 0.01-5 mass% of a phenolic oxidation inhibitor and/or an aminic oxidation inhibitor, (B) 0.01-10 mass% of a phosphorus compound and/or a sulfur compound, and (C) 0.001-5 mass% of one or more compounds selected from the group of compounds by formulas (1)-(3) described below, but does not contain zinc dithiophosphate practically. The three formulas are (1) R1-CO-NR2-(CH2)n- COOX, (2) [R1-CO-NR2-(CH2)n-COO]mY, and (3) [R1-CO-NR2-(CH2)n-COO]m- Z-(OH)m'. |
