Hujo Ľ., Tkáč Z., Tulík J., Kosiba J., Uhrinová D., Jánošová M. (2016): Monitoring of operation loading of three-point linkage during ploughing. Res. Agr. Eng., 62: 24-29.The research was focused on operational measurements of tractor plough tools and their subsequent utilisation and simulation under laboratory conditions by a hydrostatic simulator. In this field, theoretical and experimental works were focused on tractors, whereby the proposal of laboratory test arose out of the loading characteristics of the three-point linkage of the tractor. These characteristics were obtained from the agricultural tractor's operation in plough aggregation. Measurements were performed with the following tools: tractor with carrier-mounted four-mouldboard plough PH1-435 and tractor with Kuhn plough manufactured by. The subject of these measurements was to obtain the time courses of forces and pressures in the hydraulic system of the three-point linkage during ploughing with carrier-mounted and semi-mounted ploughs. For objective comparison of the obtained results during experimental measurements, we determined the characteristics of measurement conditions focused on physical and mechanical properties of the soil -bulk density, moisture, penetrometer resistance and slide strength of the soil.

This publication deals with the dra of measurement chain for application of synthetic organic liquid Hydros Uni in agricultural tractor Zetor Proxima 7441. The used organic liquid was evaluated on the basis of its eff ect on the technical condition of hydrostatic converter UD 20. By the dra ed measurement chain, it was performed individual measurements which were realized by specifi c engine speed and prescribed temperature. Then, the fl ow values were statistically analyzed. From the obtained results, it could be concluded that the proposed measurement chain meets the requirements for measuring the fl ow characteristics of liquids. Based on the results show, organic synthetic transmission hydraulic fl uid does not negatively aff ect the technical condition of the tractor hydraulic pump.

Solid carbon (C) is produced during hydrocarbon fuels combustion by the molecules heat decomposition process in a local lack of oxygen. More reactive hydrogen consumed the part of oxygen in the zone of an oxygen-rich mixture, so carbon particles are not gaining access to oxygen. Solid carbon particles are bound to other various materials such as mechanical impurities, sulphates, condensates, and liquid fuel residues, some of them with high toxicity – such as polycyclic aromatic hydrocarbons (PAH). The cause of high solid carbon emissions is a significant inhomogeneity of the mixture up to the value λ = 0 inside the fuel droplets where oxygen absences up to λ = ∞ in the space where fuel does not even come. Therefore, solid carbon emissions highly depend on the quality of atomization of the fuel which is injected into the cylinder. The supply of oxygen required for oxidation is improved by increasing the total amount of the air in the cylinder. In Slovakia as well as in other countries (the Czech Republic, etc.), there have been recently multiple instances of removing catalysts from vehicles by services, deactivation of diesel particulate filters (DPF, SCR), or vehicle control units reprogramming (tuning), or a combination of the previous actions. From the perspective of a company and its interest, it is a large interference with vehicle design, and it also affects the relationship with the environment. From the perspective of society, it is irrelevant whether it is the individual's conduct or the conduct of certain groups. This article explores the possible solutions for checking the illegal diesel engines conversion due to deactivation of particulate matter filters in exhaust systems of diesel engines as well as the current legislation that covers this issue.

A test bench for biodegradable hydraulic oils generates pressure surges by cyclic pressure loading. The parameters of these pressure surges (maximum pressure, amplitude, frequency etc.) are defined by the characteristics of the pressure valve and pipe line system. The response of the hydraulic system was recorded and studied in the case of four test bench modifications by comparing the maximum pressure, maximum pressure increase and the opening time of the pressure valve. The test bench with steel pipe between the hydraulic pump and pressure valve shows the highest maximum pressure increase (4.28 MPa). The opening times of pressure valve were measured for the evaluation of dynamic stability of the test bench. In case of all test bench modifications the opening time of pressure valve did not exceed the calculated limit value. The experiments were also aimed at the response of hydraulic system to three different frequencies (1.5 Hz, 2.5 Hz and 5 Hz) of cyclic pressure loading. Increasing the frequency only minimally increases the maximum pressure during the pressure surge. On the other hand, it increases maximum amplitude after the maximum pressure depending up to frequency of cyclic pressure loading. Fast Fourier Transform (FFT) confirms the facts mention above.

Hydraulic pumps are the most important components of hydraulic circuits in agricultural tractors. Their durability is influenced by flow characteristics and thus the flow efficiency. This paper presents the laboratory test of an ecological synthetic hydraulic fluid of UTTO type. This fluid is currently under development. In terms of a decrease in hydraulic pump flow efficiency, laboratory tests of these fluids did not show negative effects of its application. It can be stated that after completion of laboratory tests, it will be needed to continue with trials under operational conditions.