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U ovom radu predstavljen je metod za eksperimentalno određivanje parametara pogonskog mehanizma obrtne platforme hidrauličnih bagera sa dubinskim manipulatorom. Definisan je matemetički model kojim se određuju kinematički i dinamički parametri pogonskog mehanizma obrtne platforme hidrauličkih bagera, na osnovu mrenih veličina stanja rada bagera u eksploatacionim uslovima. Dobijeni eksperimentalni rezultati pokaziju da su najveća opterećenja aksijalnog lezaja pogona okretanja platforme pri operaciji kopanja. Osim toga izrazite dinamičke promene parametara hidrostatičkog sistema pogonskog mehanizma obrtne platforme javljaju se pri operaciji prenosa materijala.

Abstract:Plants from genus Seseli, have been widely used in European traditional medicine, exhibiting antibacterial, antifungal, insect repellent, emmenogogue, antiflatulence, anti-inflammatory, antinociceptive, anti-tumor, antirheumatic activities and protective effect on human lymphocytes DNA. They usually grow on mountain rocky terrains. Part of their habitat on Vidlic Mountain, located in South-east Serbia, was struck with a large wildfire. Seseli rigidum fruit essential oils (from post fire and control areas) compositions were analyzed by GC and GC-MS, identifying monoterpenes α-pinene and sabinene as most abundant. Statistical tests showed a non-significant difference in chemical composition of these two oils, but a significant difference in comparison with the herb from a geographically different origin. Antimicrobial tests showed strong activities of the oils against tested bacteria, thus confirming its administration in various inflammation processes as a quite effective remedy. Applying DPPH . and ABTS + . radical scavenging and total reducing Fe(III) to Fe(II) power assays, antioxidant characteristics of both studied essential oils were estimated as weak, though of close values. Seseli rigidum fruit essential oil was proven as a potent inhibitor of human and horse serum cholinesterase, recognizing its possible application as neural protective agent.

The paper presents the results of a numerical and experimental analysis of the dynamic stability of hydraulic excavators. The analysis has employed the software developed on the basis of a defined general dynamic mathematical model of an excavator grounded in Newton-Euler equations as well as the measured quantities of the excavator operating state in exploitation conditions. The defined model is used to model the members of the excavator kinematic chain using rigid bodies while the actuators (hydraulic cylinders and hydraulic motors) of the excavator drive mechanisms are modeled with elastically dampened elements. The elastically dampened characteristics of the actuators are defined with regard to the size of the actuator as well as to the compressibility and temperature of the hydraulic oil used in the excavator hydrostatic drive system. To illustrate the analysis, the paper provides the results of the analysis of the dynamic stability of a 16000 kg tracked excavator equipped with a manipulator digging bucket of 0.6 m3 in capacity.