The efficiency of quarry hydraulic excavators will depend on several factors, namely the climatic conditions of the area where hydraulic excavators are used, the degree of air pollution (pollination), the performance of the structural parts of the excavator, the reliability of the hydraulic system, the performance and cleanliness of the hydraulic working fluid. In this area, research was carried out on the performance of seals used in the hydraulic system of quarry excavators. The article presents the results of experimental tests of the existing type of oil seal a and b, as well as the proposed oil seal type c, shown in Fig. 1. [ABSTRACT FROM AUTHOR]