Prilog sintezi pogonskog mehanizma obrtne platforme hidrauličkih bagera

Abstract

The dissertation defines the general methodology for the synthesis of the slewing platform drive mechanism of hydraulic excavators. The methodology of the synthesis of the drive mechanism of the excavator slewing platform is based on the modular design process, by which the drive components are defined on the basis of the parameters of drive functions and functional constraints of the available components of the drives produced by specialized manufacturers. The obtained research results are related to: the analysis of the parameters of drive functions, the selection of the axial bearing, and the synthesis of the slewing platform drive mechanism of the excavator. An analysis of the function parameters, i.e. the load components and the energy parameters of the drive mechanism of the excavator slewing platform, was carried out through numerical and experimental analysis based on the developed general dynamic mathematical models of excavators and software. The analysis of the function parameters shows that the primary influence on the platform drive is exerted by the forces and moments of the digging resistance and the gravitational force of the members of the kinematic chain and the affected material. For the selection of the size of the drive mechanism axial bearing, mathematical models and software were designed to determine the spectra of loads, which are used, in relation to the permissible load bearing capacity, to select the appropriate bearing size from a set of the available ones. The load spectrum builds equivalent load forces and moments, which are defined on the basis of the limit of the digging resistance that enables the stability of the excavator and that can overcome the maximum operation of the drive mechanisms of the excavator manipulator. The results of the conducted research, within the framework of the dissertation, show that for the selection of the axial bearing of the slewing platform, the equivalent loads that occur during the digging operation with the backhoe and shovel manipulator are applicable. A mathematical model is defined for the synthesis of the drive mechanisms of the slewing platform and software is developed for generalizing possible variant drive solutions by selecting the drive components: hydraulic pump, hydraulic motor and planetary gear, from the files of the available components according to the parameters of the drive functions and the selected axial bearing size. The results of the synthesis show that for the same given parameter functions, variant solutions are generated with different transformational and transfer parameters, i.e. with hydraulic motors with a smaller specific flow and a higher ratio and vice versa.