Simulação da estabilidade de tratores agrícolas 4x2

Abstract

RESUMOO objetivo do trabalho foi simular computacionalmente a estabilidade de tratores agrícolas 4x2. Experimentos de simulação foram realizados visando analisar o comportamento dinâmico de um trator agrícola 4x2 trabalhando em diferentes condições de operação e de terreno. Nas simulações em que se variaram as posições do trator sobre uma pista inclinada até o tombamento lateral, o ângulo de posição igual a 60º foi o de pior situação, o que corresponde ao trator descer por uma diagonal em pista inclinada para a esquerda. A bitola e a localização do centro de gravidade na vertical foram os fatores que mais afetaram a estabilidade do trator em tombamentos laterais. Já, a localização do centro de gravidade na longitudinal e a distância entre eixos afetaram mais a estabilidade do trator em tombamentos para trás. O trator deslizou os rodados do lado do tombamento ou perdeu a dirigibilidade dos pneus frontais com ângulos inferiores aos limites de estabilidade para tombamento.Palavras-chave: mecanização agrícola, tombamento, segurança ABSTRACT SIMULATION OF THE STABILITY OF 2WD AGRICULTURAL TRACTORSThe objective of this work was to predict the loss of 2WD tractors stability. Simulations were done to analyze the dynamic behavior of an agricultural tractor working in different operation and surface conditions. Simulating different tractor positions on an inclined track until its side overturn, the tractor angle position of 60° presented the worst situation, what represented a tractor moving diagonally down on a left inclined track. Changing the tractor geometry and weight in the simulations, the vertical position of tractor central mass and its tread width were the parameters that most affected the tractor stability to side overturn. The longitudinal position of tractor central mass and the distance between its axes influenced on the tractor stability to rearward overturning. The tractor either slip the wheels at the side overturning or lost the front tire controlling at angles less than the overturning limits.

Evaluation of tractive performance of four agricultural tractors in laterally inclined terrain

“…Observing the values shown in Table 2, the medium slippage of the left-side tires increased with the increasing of the lateral inclination of the test track for all tractors, showing a quite high increase in the slippage because of the transfer of lateral weight shifted to the right-side of tractors, losing the tire/ground contact, according to KHOURY JUNIOR et al (2009).…”

“…It can be seen in Table 3 that the tractor T1 got the lowest significant differences between the inclinations, which can be attributed to the higher static load on the rear tires, as shown in Table 1, thereby increasing the tractive force due to the weight transfer, as according to KHOURY JUNIOR et al (2009).…”

“…Table 2 shows the average values run of slippage on the right-side tires, left-side tires, and total slippage tractors relating to the lateral inclination of the track. According to the results presented in Table 2, the slippage of the right-side tires increased with increasing of the lateral inclination of the track to the tested tractors, except for the tractor T4, which obtained a minor slippage on the 25 degrees inclination on the tests of lateral track, which can be attributed to the greater weight transfer for the occurrence of the displacement of the center of gravity to the right side, due to increased lateral inclination of the track, according to KHOURY JUNIOR et al (2009). The T1 tractor was the only one whose slippage of the right-side tires was in the range of maximum tractive efficiency until the inclination of 10 degrees, according to MÁRQUES (2008), and 15 degrees forward, as ASABE (2006).…”

“…These deformations depend on the reactions applied on the tires, which results in the increasing of the lateral inclination of the chassis, in relation to the track, decreasing the stability of the tractor (KHOURY JUNIOR et al, 2009). …”

Influence of field slope and coffee plantation age on the physical properties of a red-yellow Latosol

“…Under the upper track physical alterations were more intense than at the other sampling positions, because in the upper track slippage was higher and OM content lower. The tire slippage can be attributed to the greater weight transfer resulting in a lateral shift of the center of gravity, due to the increased lateral inclination of the track (Khoury Junior et al, 2009), causing the loss of the tire-ground contact. The contact loss is expected at higher field slopes (Leite et al, 2011).…”