Experimental investigation of the influence of fluid viscosity on the efficiency of a crawler excavator

Abstract

In view of decreasing energy resources and the rising problems associated with CO2 emissions and global warming, there is a strong interest in reducing the fuel consumption of machines in all sectors. Manufacturers of mobile machinery, such as hydraulic excavators, are also striving to develop increasingly efficient machines. Triggered by this development trend, the power density of hydraulic systems and their components continues to increase. This results in higher pressures, temperatures and lower oil volumes in the system. As a result, the hydraulic fluid used is subject to greater thermal stress and the systems thermal properties are becoming increasingly important. Further developments of tribological systems, for example in hydraulic displacement units, also create new demands on the hydraulic components and fluids. The fluid properties in particular are increasingly coming to the fore. For this reason, the content of this paper is to consider the influence of the hydraulic oil’s viscosity on the efficiency of a crawler excavator and to present the viscosity dependent losses of valves and pipe/hose lines. To this purpose, experimental tests are discussed by regarding viscosity related energy losses of the hydraulic system of a crawler excavator. Therefore the results of experimental tests of a gravel cycle at different temperatures will be discussed. The results are divided into different types of energy losses. Finally, a hypothesis can be made about the dependence of the viscosity of the hydraulic fluid on the efficiency of the system.