Pexa M., Cindr M., Kubín K., Jurča V., 2011. Measurements of tractor power parameters using GPS. Res. Agr. Eng., 57: 1-7.Understanding of the power parameters of an agricultural energy device (tractor) is very important in relation to the final outcome. This understanding is necessary to achieve high performance in combination with low economic costs and favourable ecological conditions. Monitoring the progress of power parameters (torque and engine power) is possible mainly by dynamometer, which is not affordable for common undertaking. The option of using GPS receiver to determine the torque of the engine and its backup torque seems to be an appropriate option. The data thus collected will contribute to the timely detection of defects, and thus prevent the emergence of economic and ecological consequences that are related to the tractor engine.

The paper describes the modeling of NRTC (Non-Road Transient Cycle) test procedure based on previously measured characteristics of fuel consumption, carbon monoxide (CO), carbon dioxide (CO 2 ), hydrocarbons (HC), nitrogen oxides (NO x ) and particulates (PM) production. It makes possible to compare the current technical condition of an internal combustion engine of an agricultural tractor with its previous state or other tractor's engine. Based on measured characteristics, it is also possible to model any other cycle without further measurements (NRSC test procedure, cycle for specific conditions -mountain tractor, etc.). The result may thus contribute to improving the environment by reducing the production of harmful substances emitted into the air and save money due to reduced fuel consumption.Keywords: NRTC test procedure, fuel consumption, emission characteristics Abstrakt Příspěvek popisuje možnost modelování testu NRTC (Non-Road Transient Cycle) na základě změřených charakteristik spotřeby paliva, oxidu uhelnatého (CO), oxidu uhličitého (CO2), nespálených uhlovodíků (HC), oxidů dusíku (NOx) a pevných částic (PM). Ve srovnání s předchozím zjištěným technickým stavem lze stanovit změny technického stavu spalovacích motorů zemědělských nebo lesnických traktorů. Současně však lze na základě změřených veličinových charakteristik porovnat mezi sebou libovolné traktory a také modelovat libovolný jiný cyklus bez dalšího měření (NRSC test, cyklus pro specifické podmínky -horský traktor apod.). Ve výsledku lze tak přispět ke zlepšení životního prostředí snížením produkce škodlivých látek vypouštěných do ovzduší a současně uspořit peníze sníženou spotřebou paliva.

Pexa M., Kubín K., 2012. Effect of rapeseed methyl ester on fuel consumption and engine power. Res. Agr. Eng., 58: 37-45. This paper describes the effect of a mixture of rapeseed methyl ester and diesel oil on fuel consumption and power parameters of tractor engine. The hydraulic dynamometer was used to load the engine of Zetor Forterra 8641 tractor over rear power take-off. The measured tractor is almost new with less than 100 h worked. The measurements were realized for several ratios of diesel oil and rapeseed methyl ester (from pure diesel to pure rapeseed methyl ester). The engine was loaded by the dynamometer in several working points which were predefined by engine speed and its torque. The fuel consumption was measured by the flow meter in each of these points. The reduction of engine's power parameters and the increase of specific fuel consumption are expected due to the nature of rapeseed methyl ester such as e.g. lower calorific value.

Pexa M., Kubín K., 2014. Effect of rapeseed methyl ester on emission production. Res. Agr. Eng., 60: 1-9. This paper describes the effect of a mixture of rapeseed methyl ester and diesel oil on emission production of tractor engine. The hydraulic dynamometer was used to load the engine of Zetor Forterra 8641 tractor over rear power take-off. The measured tractor is almost new with less than 100 h worked. The measurements were realized for several ratios of diesel oil and rapeseed methyl ester (from pure diesel to pure rapeseed methyl ester). The engine was loaded by the dynamometer in several working points which were predefined by engine speed and its torque. The production of carbon monoxide (CO), carbon dioxide (CO 2 ), hydrocarbons (HC), nitrogen oxides (NO x ) and particulate matter (PM) were measured in each of these points. The comparison of different fuels was performed using the Non-Road Steady Cycle (NRSC) test procedure. Engine maps were also created for each emission component and for all of tested fuels.

This contribution presents a calculation method of indicators in agricultural transport. The tractor Zetor Forterra 8641 with a silage trailer was used. Calculations were performed with various weights of transported material: 2.5, 3.6, 5.8, 7.4 and 9.0 tons. The model was created concerning significant parameters of the transport set, engine characteristics and route. It considered splitting of the route into elementary sections, in which important route parameters were regarded as constant. Indicators were defined in every section (fuel consumption, emissions, etc.) and overall values were calculated as a sum. The set with 7.4 t of load reached the lowest unit costs 20.62 CZK·tkm^–1, transport output 79.51 tkm·h^–1 and unit consumption 0.14 L·tkm^–1. The set with the maximum load 9.0 t reached output 86.05 tkm·h^–1 but unit costs were 20.68 CZK·tkm^–1. Using the maximum capacity was not the most effective option. When the weight of a load increased (from 2.5 to 9.0 t), driving time extended from 0.28 to 0.46 h and hourly transportation output increased from 38.60 to 86.05 tkm·h^–1, unit consumption decreased from 0.24 to 0.13 L·tkm^–1. Total emissions significantly increased, but unit emissions decreased in average two times for each pollutant.