The Behaviour of Hydraulic Systems in Low Operating Temperatures

The behaviour of hydraulic control and power systems in subzero temperatures is important to designers and operators of hydraulically driven and controlled mobile machinery which have to operate in a cold climate environment. The paper presents typical results of tests on hydraulic fluids and on components of a hydraulic system in temperature down to -50°C. The low-temperature behaviour of the hydraulic systems was characterised by non-Newtonian characteristics of the hydraulic fluid, increased pressure losses, lower system efficiency. The effect of low temperatures on rheological properties of hydraulic fluids and characteristics of basic hydraulic components used in mobile machinery are discussed.