Vibrações em um trator agrícola cabinado: magnitude das acelerações no assento e transmissibilidade através do coxim

Abstract

The tractor is the machines that provides the largest percentage of power used on rural activities inside the agricultural automation, making the researches on parameters of the vibration frequency on the rubber grommet and the tridimensional magnitude more convenient, in order to contribute to the future engineering researches. Therefore, this work has the main objective to analyze the magnitude of efficient accelerations on the seat-operator interface and the vibrations transmissibility of the rubber grommet on the agricultural tractor with a cabin, using three adjustment knob positions, two scarification depths, two displacement speeds and three different ballast settings. The experiment was held at the Phytotechny School s experimental area (Federal University of Santa Maria) through a subdivided portion outlining with 4 repetitions and 144 experimental units. A 4x2 TDA tractor was used with 63 kW of power on the engine (63 kW) attached to the chisel plow. The information was recorded by the accelerometers that were installed on the floor of the cabin, platform, rubber grommet and on the seat. It was concluded that the magnitude of efficient accelerations obtained on the seat-operator interface in all the 36 individual tests stayed above the comfort limit on the frequency of 1 to 80Hz, established by the standard (ISO 2631-1: 1997) for daily 8-hour exposure. The magnitude of efficient accelerations on the vertical direction (z) in the tractor s cabin floor in all the 36 individual tests had comfortable rates for the total metallic ballasting (TMB) and little uncomfortable for both the partial metallic ballasting (PMB) and the total hydraulic ballasting (THB) according to the (ISO 2631-1: 1997). The vibration transmissibility, on the direction (z) through the rubber grommet, had an amplification in the interval from 0 to 15Hz for TMB, from 0 to 19Hz for PMB and from 71 to 76Hz for THB. The transmissibility rates in the analysis between 1 and 80 Hz corresponded to 59%, 74% and 88% for TMB, PMB and THB, respectively. In all the individual tests, the vibration transmissibility from the floor to the seat was around twenty times higher compared to the vibration transmissibility from the platform to the tractor floor, using the frequency range from 1 to 80 Hz. On the virtual dynamic simulation, the elastomer provided around 11% reduction for the vibration magnitude on the seat-operator interface in the vertical direction.