The purpose of this study is to improve the technical and economic performance of the enhanced two-machine seeder based on the wheel-type tractor of traction class 1.4. Experimental research is based on the general provisions of the standard methodology for operational and technological evaluation of the operation of machine-tractor units in the field. Processing of results from experimental study was carried out by means of developed programs on a PC. Results obtained from field experiments testing the aggregate consisting of two-machine seeder of traction class 1.4, two SZ-3.6 seeders and a semi-mounted coupler indicate its high operational and technological efficiency in comparison to both single-machine and similar two-machine units as part of a conventional trailer hitch. Although it shows an increase in specific time losses at headland of up to 5%, due to the wider working width, utilization of a new two-machine unit on the basis of a semi-mounted coupling in comparison with a single-machine unit allows increasing the productivity of the work by 1.96 and reduction of fuel consumption by 20%. In order to ensure that two-machine unit will perform turning on headland in the optimal mode, it is necessary to equip it with a special automatic device that would change the speed of movement in compliance with the angular speed of tractor‘s steering wheels according to the developed algorithm.

This research deals with the corrosion stability of components with a galvanized surface. The aim is to determine how corrosion resistance is influenced by chemical degreasing. The ZiNi galvanizing method in a bath line was performed on 10 components; another 10 pieces were treated by the same galvanizing method, but without previous chemical degreasing. After measuring the thickness of coating, components were inserted into a salt spray corrosion chamber. The test showed that components with a complete galvanizing process revealed no signs of red corrosion after 456 test hours. In components without chemical degreasing, there were signs of red corrosion after 200 test hours. After this research, we can conclude that chemical degreasing in galvanizing processes has a high influence on corrosion resistance.

Polák P., Mikuš R., Kročko V., 2014. Monitoring of conditions of agricultural machines' parts in operation. Res. Agr. Eng., 60 (Special Issue): S57-S65.This contribution focuses on problems of monitoring the runout of tractor diesel motor parts used in agricultural operation. Crankshafts from the agricultural tractors of type Zetor 6911 are used as samples for measuring the runout and circularity. The first sample of the crankshaft is loaded in the tractor used in livestock production, and the second one is used in vegetable production. Measured values of the runout and circularity of both samples are evaluated by tables and polar diagrams. Results of the experiment show the amount of runout and the following wear of agricultural machine parts in different operating conditions of agricultural production.

The aim of this research is, to investigate the influence of two types of cyclic salt spray tests on parts surface treated with galvanizing. On the selected components was performed the method Zn-Ni surface treating on the bath line. Subsequently were the components embedded in the corrosion chamber, where was performed two types of cyclic salt test. In the first test was performed 4 hour salt spray, 8 hours drying, 60 hours condensation and 24 hours drying. Once cycle lasted 96 hours, and it was repeated 4 times. During the second test was performed 2 hours salt spray, 2 hours condensation. The cycle was repeated 4 times, that means 96 hours. After the cycle was performed 72 hours free relaxation in the corrosion chamber, on 20–25 °C temperature. As the research showed, after the cyclic salt spray was no red corrosion on the selected components. The white corrosion appeared only slightly.

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