Parâmetros de projeto e desempenho de tratores agrícolas a partir do banco mundial de ensaios

Abstract

Nowadays, the agricultural tractor is considered to be one of the most important agricultural equipment, due to their versatility at performing a great number of field operations. Since its creation in the mid-1850s, various types and sizes of tractors have been developed, evolving according to changes in technologies, size of agricultural areas and specific functions that they need to perform. Thus, this work aimed to analyze the main design and performance parameters used in the project of agricultural tractors through official test reports available at international database. Were analyzed the main changes in framing and performance, besides the influence that the air intake device exerts at the engine performance. The present work was carried out by obtaining, processing and analyzing data from 888 official agricultural tractor test reports, specifically from agricultural tractors with three and four cylinders engines. Through the selecting of the test reports carried out between the years 1993 to 2018, which follows OECD Standard Test (Code 2) and, which are available in the databases from the Nebraska Tractor Test Laboratory (NTTL) and from the Organization for Economic Co-Operation and Development (OECD). The main results demonstrate that the mass/power ratio of agricultural tractors with three and four-cylinder engines decreased between the years 1993 and 2018, indicating an increase at the versatility of the tractors. The mass of agricultural tractors with three-cylinder engines decreased by approximately 6.38%, while the mass of agricultural tractors with four-cylinder engines showed an approximate growth of 42.66% during the analyzed period. The displacement/power ratio showed decreasing behavior between the years 1993 and 2018 for both agricultural tractor settings, showing this reduction at percentage values of 25.76% and 50.09%, respectively for tractors with three-cylinder and four-cylinder engines. In addition, agricultural tractor engines have become more efficient in terms of performance. As for the air intake of the engines, the use of supercharging in the engines of three and four cylinder at agricultural tractors improves their performance by providing greater torque and power, and reducing the specific fuel consumption when compared to natural air aspiration engines. Besides, the downsizing of agricultural tractor engines occurs.