Research in Agricultural Engineering, 2008 (vol. 54), issue 4
INDEX OF VOLUME 54
editors
Res. Agr. Eng., 2008, 54(4):I-III | DOI: 10.17221/701-RAE 
Evaluation of thermooxidation stability of biodegradable recycled rapeseed-based oil NAPRO-HO 2003
M. Kučera, M. Rousek
Res. Agr. Eng., 2008, 54(4):163-169 | DOI: 10.17221/11/2008-RAE
The paper deals with the problems of introducing biodegradable oils in relation to the environmental protection. In the course of the research, the parameters were tested and improved of a number of rapeseed-based oils. Thus, two groups of oils were created to enable to distinguish raffinates and recycled oils. Recycling can remove the greatest disadvantage of raffinates, namely their thermo-oxidation instability, which becomes evident particularity by the formation of hardenable polymer deposits. The deposits result in the loss of the function of the components of the hydraulic circuit and gearbox. The methods of testing are based on the follow-up...
Effect of heat treatment on re-solubility of potato proteins isolated from industrial potato fruit juice
V. Bártová, J. Bárta
Res. Agr. Eng., 2008, 54(4):170-175 | DOI: 10.17221/703-RAE
The contribution deals with thermal stability and re-solubility of potato tuber proteins isolated by ethanol precipitation from industrial potato fruit juice. The protein isolate was exposed to the temperatures ranging from 25°C to 70°C. Patatin, the tuber protein with a high nutritious value, was detected by SDS-PAGE in the region of 39-43 kDa. Patatin was evaluated as thermal sensitive - temperatures above 30°C caused its strong insolubility. Potato protease inhibitors were detected in the region from 4.3 to 24 kDa. Thermal stability of potato protease inhibitors (region from 25 to 14 kDa) was higher, although the temperatures above 45°C caused...
Relation between surface temperature and dryer operation
I. Vitázek, J. Tirol
Res. Agr. Eng., 2008, 54(4):176-182 | DOI: 10.17221/14/2008-RAE
The most significant way of grains conservation is heat drying. This technological process is regarded as a part of the production process with such commodities as grain maize, grain sunflower, rape, and other oil plants. The paper presents partial results of a check measurement on MC 3180 dryer with descending vertical layer in drying grain maize. On the basis of the evaluation of the measured parameters of the drying medium and the analysis of thermovision camera screenshots together with applying the knowledge of the mechanics of wet air, insufficiencies in the dryer operation were revealed and specified. Significant diferences in surface temperatures...
Testing stands for laboratory tests of hydrostatic pumps of agricultural machinery
Z. Tkáč, Š. Drabant, R. Majdan, P. Cvíčela
Res. Agr. Eng., 2008, 54(4):183-191 | DOI: 10.17221/704-RAE
In this paper, a design of testing stands for the durability tests of hydrostatic pumps of agricultural tractors is presented. The designed testing stands will be used for the laboratory verification of the influence of biodegradable oils on the durability of tractor hydrostatic pumps. The designed testing stands were built and tried out. On the basis of the results achieved in the system function tests, we can say that the testing stands are suitable for the durability tests of hydrostatic pumps.
Abrasive wear of high chromium Fe-Cr-C hardfacing alloys
R. Chotěborský, P. Hrabě, M. Müller, J. Savková, M. Jirka
Res. Agr. Eng., 2008, 54(4):192-198 | DOI: 10.17221/1/2008-RAE
Weld deposits are one of the most used economical ways of the wear resistance increase. The study compares the characteristics of the overlay material welded-on and the abrasive wear resistance. The research has been carried out using hardfacing alloys reinforced with primary chromium carbides and complex carbides. The overlay material was deposited on the low-carbon steel S235JR using the gas metal arc welding (GMAW) method. Four different commercial overlay materials were studied in terms of the microstructure effect. The abrasion wear testing was carried out using the abrasive cloth of grit 120 according to CSN 01 5084. The microstructure characterisation...
Influence of using time of selected agricultural machines and tractors on residual market price, repair costs, and annual utilisation
J. Sailer, M. Kavka, P. Kavka, P. Kavka
Res. Agr. Eng., 2008, 54(4):199-207 | DOI: 10.17221/705-RAE
For each new machine designed operational parameters exist and the realisation of these parameters determines the ability to perform the operations which it is designed for. It was proved both technically and practically that there is an impact of the using time of machines on the level of realisation of the operational parameters. Based on a selective the statistic survey, the impact is analysed in the article of the using time of selected agricultural machines and tractors on the residual market price, repair costs, and the trend of annual utilisation. The outcome is a functional dependency of decreased residual market price, the growth of repair...