HYDRAULIC FLUID COMPOSITION

摘要

Provided is a hydraulic fluid composition that has a viscosity index of at least 150, and a ratio (A/B) of the kinematic viscosity (A) (units: mm2/s) and shear viscosity (B) (units: mPa·s; shear conditions: 106/s) at 60-80°C of no greater than 1.3, and that contains a lubricant base oil having a kinematic viscosity at 40°C of 15-50 mm2/s and a polymethacrylate having a number average molecular weight of no greater than 48,000 and constituting 1-40 mass% of the entire amount of the hydraulic fluid composition.