ERGONOMIC EVALUATION OF VIBRATION AND NOISE EMISSIONS OF AGRICULTURAL TRACTORS BASED ON POWER AND WORKING TIME

摘要

Mechanization is essential in modern agriculture. The tractor is one of the machines responsible for the agricultural progress observed in the second half of the twentieth century. The improvement and reliability of these machines has allowed for an industrial revolution, facilitating the clearing of large areas of native vegetation and the economic expansion of the production of agribusiness commodities. However, tractor efficiency, as well as the occurrence of accidents, depends partly on the level of operator fatigue. Of all the ergonomic factors affecting the operator of the machine, noise and vibration are the most important, but few studies have evaluated these parameters and their implications for occupational health. This study aims to evaluate the levels of vibration and noise emitted by agricultural tractors of different power ratings and to compare the results with existing regulations in Brazil. The tractors studied were as follows: tractor A (engine power of 63 kW (86 cv) at 2200 rpm, manufactured in 2005, 4050.5 h of operation), tractor B (engine power of 88 kW (120 cv) at 2200 rpm, manufactured in 2005, 3800.0 h of operation), tractor C (engine power of 127 kW (173 cv) at 2200 rpm, manufactured in 1997, 7472.9 h of operation), and tractor D (engine power of 81 kW (110 cv) at 2200 rpm, manufactured in 2011, 907 h of operation). For all four tractors, the noise levels were above the recommended values, while the vibration levels were typically below the limits established for 8 h of work at frequencies of 5 to 10 Hz. Furthermore, the level of vibration was strongly related to the seat structure of the tractor, which can efficiently cushion impacts on both asphalt pavement and firm ground