Tag Archives: combine harvester

xxx M. Mimra and M. Kavka
Risk analysis regarding a minimum annual utilization of combine harvesters in agricultural companies
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Risk analysis regarding a minimum annual utilization of combine harvesters in agricultural companies

M. Mimra* and M. Kavka

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Machinery Utilisation, Kamýcká 129, CZ165 21 Prague 6–Suchdol, Czech Republic *Correspondence: mimra@tf.czu.cz

Abstract:

This article presents the results of entrepreneurial risk analysis concerning a minimum annual utilization of harvesters in a company providing agricultural services where a group of combine harvesters is used. Furthermore, this article presents the following analysed key operating parameters with the greatest influence on reaching the minimum annual utilization and performance: the changing market price of mechanized work, the volatile purchase price of the machines, average maintenance costs).
Partial profit which an enterprise can reach through operating combine harvesters is directly affected by the level of their annual utilization. Not reaching the minimum annual utilization of combine harvesters would create losses that could result in termination of business activity in the specific field or even insolvency of the company. It is therefore necessary to monitor the key factors which influence the minimum annual usage and in case of negative developments to take timely corrective actions.

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25-32 L. Beneš, P. Heřmánek and P. Novák
Determination of power loss of combine harvester travel gear
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Determination of power loss of combine harvester travel gear

L. Beneš*, P. Heřmánek and P. Novák

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Agricultural Machines, Kamýcká 129, 165 21 Prague 6, Czech Republic;
*Correspondence: benesl@tf.czu.cz

Abstract:

This contribution aims at determining the power loss in hydraulic circuits of the John
Deere S680i combine harvester travel gear. The individual elements of the circuit were measured,
followed by an energy intensity analysis. The analysis includes the calculation of pressure losses
in direct piping, local resistance, as well as pressure losses in the individual elements of the
circuit. Subsequently, power loss was calculated based on pressure losses. In the case of the John
Deere S680i combine harvester, the power loss equals 16.95 kW.

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377-385 D. Steponavičius, L. Špokas and S. Petkevičius
The influence of position of the first straw walker´s section on grain separation
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The influence of position of the first straw walker´s section on grain separation

D. Steponavičius, L. Špokas and S. Petkevičius

Department of Agricultural Machinery of Lithuanian University of Agriculture,Studentu St.15A, LT 53362 Akademija, Kaunas r., Lithuania;e-mail: Dainius.Steponavicius@lzuu.lt

Abstract:

The impact of the inclination angle of the first section (screen) of straw walkers on grain separation through the straw layer of various thicknesses has been tested in the laboratory. The straw feed rate on the straw walkers and the Froude number of the straw walkers (rotational speed of the walker crankshafts) was changed during the test. About 20% of the grains threshed and unseparated through the concave of the threshing device remained trapped in the straw layer fed on the straw walkers. It has been defined that the inclination angle of the first section of straw walkers were related to the straw throughput and the rotation speed of the walker crankshafts. The greatest number of grains was separated through the straw layer when it fell from the first section of straw walkers onto the second one. The optimum value of Froude number of the fourth straw walker assembly was 2.58 (the rotational speed of the crankshafts was 215 min-1), the inclination angle of the first straw walkers section was 22º, a step height was 0.28 m, the permissible limit straw feed rate on the straw walkers of dry straw (moisture content 9.8%) was 2.08 kg (s m)-1 on the layer with 0.43 m thickness because then only 3% of unseparated grains reach the fourth section of straw walkers with the straw. The intensity of grain separation can be controlled using the rotational speed of the crankshafts or the inclination angle of the first section of straw walkers.

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