All Season Petroleum Hydraulic Fluid for Ground Equipment

Abstract : A low viscosity petroleum base hydraulic fluid having anti-wear, rust protection and oxidation stability characteristics, has been developed for the gun and turret control system of the M48A2 and M60 tanks. The fluid has a viscosity of 1.32 centistokes at 98.9 C and 381 centistokes at -53.9 C, (low temperature viscosity was dictated by low temperature starting requirements) thereby permitting operation within minutes at -53.9 C, and satisfactory performance at bulk fluid temperatures of approximately 98.9 C. Performance at the latter temperature is comparable to that obtained with currently specified MIL-H-6083B hydraulic fluids. After a test of 213 hours, wear, leakage and corrosion were negligible or nonexistent and no significant changes in fluid properties were noted. This fluid eliminates the need for hardware modifications (installation of heaters) in order to permit usage at low temperatures of the more viscous MIL-H-6083B specification fluids or alternatively the costly option of using and stockpiling more than one fluid (different viscosities) in order to achieve all weather capability.