Influência de superfícies de rolamento na vibração de corpo inteiro transmitida ao operador de trator agrícola

Abstract

In a world where large-scale production dominates the work pace, the tractor operator is required to have contact with the machine for longer hours throughout their daily work shift. One of the problems associated with this daily contact with the tractor is the exposure to whole-body vibration (WBV) transmitted to the operator, which can lead to health issues such as muscle injuries and spinal disorders. This study aims to analyze how different rolling surfaces impact the vibration levels experienced by the operator through the agricultural tractor. For this purpose, a 4x2 tractor with auxiliary front drive (TDA) from Valtra®, model BM 125i, was used. To investigate the vibrations transmitted to the operator, the tractor moved over four different rolling surfaces: a concrete track, a cobblestone path, an asphalt pavement, and finally, prepared soil that had been plowed and harrowed. Additionally, the surfaces were analyzed at two travel speeds, 3.5 km/h and 7.5 km/h, achieved through engine speeds of 1860 rpm in gears L2 and L4, respectively, totaling eight treatments. The following evaluation parameters were used: average acceleration, maximum peak, crest factor, normalized exposure resulting acceleration (aren), and resultant vibration dose value (VDVR). A daily work shift of eight hours was considered. Vibration measurements were taken using a Delta OHM® model HD2030 vibration analyzer, along with a model 356B41 seat accelerometer fixed to a seat pad. Data processing was conducted using Noise Studio® 6.95 software and tabulated in Excel®. For statistical

analysis, the Anderson-Darling test was performed, confirming the non- normality of the data. Subsequently, the Kruskal-Wallis test was used to

determine if any treatment differed from the others. Once it was established that there was a difference in at least one of the treatments, the Dunn post-Hoc test was employed to identify which treatment(s) showed differentiation. According to NR-15 and NHO-09 regulations, none of the treatments constituted unhealthy conditions for the operator. Concrete at both speeds exhibited the least amplification of transmitted vibration, while the cobblestone surface amplified it the most. The cobblestone and prepared soil at the higher speed were classified as regions of uncertainty, indicating that preventive and corrective measures should be taken to mitigate the vibrations experienced by tractor operators, thus providing better working conditions for professionals.