Conforto térmico de operadores de microtratores em operação de preparo do solo

Abstract

Agricultural machine operators are subjected to jobs that present quite different conditions, who have contributed to his discomfort during the workday, mainly in the Northeast region, where high levels of solar radiation and air temperature, affect thermal comfort for most of the year. Thus, the objective of this work was to evaluate the thermal comfort to which micro tractor operators are exposed during the tillage operation. The tests were conducted in the experimental area of the Agricultural Machinery Accident Investigation Laboratory (LIMA), at the Federal University of Ceará, Pici campus, Fortaleza, Ceará. For the soil tillage operation, a two-wheel micro tractor power source was used, Yanmar Agritech® brand, 2 x 2, power from 10.3 kW to 2,400 rpm, pulling a rotoencanteirador, model TA33 with 750 mm width and cutting depth 200 mm. A completely randomized design was used, where the treatments were composed by the combination of two qualitative factors: two work marches (1st and 2nd) and three schedules (6:00 am, 12:00 pm and 5:00 pm) for five days, with the days being repetitions. Seven variables were evaluated: temperature, humidity, solar radiation, physical load and fatigue, average skin temperature of the operator (face and chest) and the agricultural micro tractor. All tests were conducted according to the Brazilian Technical Standards Association (ABNT). For the analysis of the data, descriptive statistics were performed, found normality was performed the analysis of variance, the means were compared using the Tukey test, at 5% probability. Based on the temperature and relative humidity of the air, the thermal sensation was calculated, where it presented discomfort in the operating conditions, being classified as unhealthy work by NR 15. From the results, it was found that the time of greatest discomfort happened in the early and late afternoon, generating physiological stress in the operator. For analysis of the physical workload during the soil tillage operation, it was classified as moderately heavy, but did not require rest breaks during the hour worked. Finally, the average temperature of parts of the operator's body (face and chest) and of the mechanized set (micro tractor and brush) was measured, using a thermographic camera, both temperatures showed higher values at 12 o'clock. It is concluded that the soil tillage operation carried out by the micro tractor operator was considered uncomfortable, due to the large thermal load, characteristic of the region's climate. And in the morning, it would be the best shift to carry out the soil preparation, without causing so much discomfort for the operator.