Template-Type: ReDIF-Article 1.0 Author-Name: L. Jílek Author-Workplace-Name: Faculty of Engineering, Czech University of Life Sciences in Prague, Prague, Czech Republic Author-Name: R. Pražan Author-Workplace-Name: Faculty of Engineering, Czech University of Life Sciences in Prague, Prague, Czech Republic Author-Name: V. Podpěra Author-Workplace-Name: Anser, s.r.o., Prague, Czech Republic Author-Name: I. Gerndtová Author-Workplace-Name: Research Institute of Agricultural Engineering, Prague-Ruzyně, Czech Republic Title: The effect of the tractor engine rated power on diesel fuel consumption during material transport Abstract: The authors of this paper determined in a field measurement how the change of the tractor engine power in a tractor-trailer combination affects the diesel fuel consumption related to the unit of transport output (l/tkm) and the transport performance (t/h) in the conditions of a mountainous region. Transport combinations (tractor - trailer) were compared that were formed by a tipping trailer connected to three tractors with different engine powers when passing allong a route with the gradient of 0°-5.5°. It is obvious from the results of these measurements that the diesel fuel consumption differed by up to 27% in individual combinations. The lowest specific consumption on the measured route was found in the combination with the tractor with the engine rated power of 50 kW (0.037 to 0.077 l/tkm), the highest consumption with the tractor with the rated engine power of 114 kW (0.056 to 0.093 l/tkm). The lowest transport performance on the measured route was found in the combination with the tractor with the engine rated power of 63 kW (19.37 t/h), the highest performance with the tractor with the rated engine power of 114 kW (43.42 t/h). Keywords: engine characteristics, transport, rated power, fuel consumption, performance Journal: Research in Agricultural Engineering Pages: 1-8 Volume: 54 Issue: 1 Year: 2008 DOI: 10.17221/710-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/710-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-200801-0001.txt Handle: RePEc:caa:jnlrae:v:54:y:2008:i:1:id:710-RAE Template-Type: ReDIF-Article 1.0 Author-Name: J. Bradna Author-Workplace-Name: Research Institute of Agricultural Engineering, Prague-Ruzyně, Czech Republic Author-Name: J. Malaťák Author-Workplace-Name: Faculty of Engineering, Czech University of Life Sciences in Prague, Prague, Czech Republic Title: By-products from methyl ester oil production and their thermal-emission properties Abstract: With the exhaustion of fossil energy sources in sight, the importance of the renewable sources of energy becomes one of the major conditions for permanently sustainable development not only in agriculture, but also in the society as a whole. The growing use of biodiesel has opened other areas of utilising the by-products from the manufacture of rape seed oil methyl ester (FARME) as an energy source, used in the combustion equipment designed for these alternative fuels. The aim of this paper is to assess the feasibility of utilising the by-products from the production of rape seed methyl ester as a source of energy, from ecology and economy aspects of the combustion equipment used. Therefore, the study is focused on the concentration of emissions generated by burning FARME, and distillation of residuals from FARME production plants. An important objective of this study lies in the determination of the stoichiometry characteristics of rape seed oil methyl esters and distillation residuals from FARME production plants. The following parameters are set by calculations: fuel heating power, oxygen amount (air) necessary for ideal combustion, flue gases amount and composition, and flue gases specific weight. Keywords: rape seed oil methyl ester, FARME, a liquid fuel, stoichiometry, combustion equipment, emissions, heating value, caloric value Journal: Research in Agricultural Engineering Pages: 9-21 Volume: 54 Issue: 1 Year: 2008 DOI: 10.17221/707-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/707-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-200801-0002.txt Handle: RePEc:caa:jnlrae:v:54:y:2008:i:1:id:707-RAE Template-Type: ReDIF-Article 1.0 Author-Name: V. Mayer Author-Workplace-Name: Research Institute of Agricultural Engineering, Prague-Ruzyně, Czech Republic Author-Name: D. Vejchar Author-Workplace-Name: Research Institute of Agricultural Engineering, Prague-Ruzyně, Czech Republic Author-Name: L. Pastorková Author-Workplace-Name: Research Institute of Agricultural Engineering, Prague-Ruzyně, Czech Republic Title: Measurement of potato tubers resistance against mechanical loading Abstract: The contribution presents a method for the determination of the potato tubers resistance against mechanical loading, the measurement results obtained with the selected potato varieties, and the comparison of the latter. For testing the potato varieties samples, the method developed in Agrartechnik (ATB) Bornim (Germany) was verified and utilised. The potato samples were exposed to vertical vibrations with adjustable amplitude in the device constructed at the Research Institute of Agricultural Engineering, (RIAE) Prague, for testing tuber samples for mechanical loading. The potato samples cutting pictures were scanned by a web camera or a scanner, and the colour changes on the cuttings were evaluated by means of a computer program. In the paper are presented the results of two different measurements. Significant differences were found between four varieties regarding their resistance against equal mechanical load, and in one variety in different degrees of mechanical load for both early and late potatoes. Keywords: potato, mechanical injuries, flesh darkening, measurement methods, tubers resistance Journal: Research in Agricultural Engineering Pages: 22-31 Volume: 54 Issue: 1 Year: 2008 DOI: 10.17221/708-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/708-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-200801-0003.txt Handle: RePEc:caa:jnlrae:v:54:y:2008:i:1:id:708-RAE Template-Type: ReDIF-Article 1.0 Author-Name: D. Herák Author-Workplace-Name: Department of mechanics and engineering, Author-Name: J. Karanský Author-Workplace-Name: Department of technological equipments of building, Author-Name: R. Chotěborský Author-Workplace-Name: Department of material and engineering technology, Faculty of Engineering, Czech University of Life Sciences in Prague, Prague, Czech Republic Title: Utilisation of the method of stress limit for designing the motion screw dimensions Abstract: A design of the motion screw using the method of stress limit is described. Further general formulas are induced to design such kind of screws, applied to an example of 11500 (EN ISO E295) steel made screw, strained by static operational force. Safety equations to prevent screw drift and their diagrams are integrated parts of the article. Keywords: Euler, Tetmayer, motion screw, slenderness ratio, stress, screw drift Journal: Research in Agricultural Engineering Pages: 32-41 Volume: 54 Issue: 1 Year: 2008 DOI: 10.17221/709-RAE File-URL: http://rae.agriculturejournals.cz/doi/10.17221/709-RAE.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/rae-200801-0004.txt Handle: RePEc:caa:jnlrae:v:54:y:2008:i:1:id:709-RAE