Navoi State University of Mining and Technologies, Navoi, Republic of Uzbekistan

N. A. Abduazizov, Vice-Principal of Education, Doctor of Engineering Sciences

A. Sh. Zhuraev, Acting Associate Professor, Candidate of Engineering Sciences

NUST MISIS, Division in Almalyk, Almalyk, Republic of Uzbekistan
G. E. Raikhanova, Deputy Director, Candidate of Engineering Sciences, galiya82@inbox.ru

Moscow State Technological University, Moscow, Russia
A. V. Vinogradov, Deputy Director of Center for Automated Machine Building Supervision

Mining enterprises of the Republic of Uzbekistan pay great attention to the improvement of quality indicators of the main excavation and loading equipment operation. The growing depth of open pit mining in difficult geological conditions and the increased requirements for reliability and efficiency of excavators lead to the expansion of application fields of hydraulic machines and to the increase of their capacity. Modern hydraulic excavators are the expensive high-tech equipment, and their operation and maintenance require strict adherence to technical regulations and specialized training of personnel. Efficiency of an excavator depends on many factors and largely on technical state of its hydraulic system. When hydraulic excavators operate in difficult climatic conditions, the number of failures of hydraulic equipment increases, and therefore issues connected with reducing the operating cost of hydraulic systems of mining excavators and with their trouble-free operation are highly relevant. Reliability and efficiency of hydraulic system components depends greatly on the purity of the hydraulic fluid used. The decrease in the service life of assemblies and parts of the hydraulic system of a hydraulic excavator occurs due to the following reasons: high concentration of solid mechanical impurities, which leads to adhesion, abrasion and erosion damage; high concentration of liquid impurities, including water and bitumen, which causes corrosion and siltation; excess concentration of air (gas), which conditions cavitation erosion. The article presents the research results on the impact exerted by the concentration of working fluid impurities on the service life of the hydraulic system of excavators. The graphical pattern of durability of hydraulic systems with respect to the level of contamination is plotted; the composition of hydraulic fluids is analyzed in terms of dust and contaminating elements, and their impact on the system is assessed; the dependence of contamination of the working fluid of the hydraulic system on the time of its use is proposed to predict the degree of contamination and to determine the optimum level of contamination of the hydraulic system.

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