Effect of engine rotation speed and gear ratio on the acoustic emission of John Deere 1055I combine harvester

Abstract

One of the problems of agricultural mechanization is noises caused by the use of machines. The noises should be evaluated due to the negative effects on health and safety level of humans working in this field. However, the purpose of this study is to investigate the effect of gear ratio and engine rotation speed on acoustic noise of John Deere 1055I combine harvester. The experiments were done based on sound international standards ISO 5131, ISO 7216 and the World Health Organization considering different levels of engine rotation speed (1800 and 2500 r/min), gear ratio (1, 2 and 3 H) and distance from the driver ear (10 cm, 7.5 m and 20 m). Three replications were considered for each treatment. The obtained data was analyzed by factorial test based on completely randomized block design. Analysis of variance showed that the interactions of engine rotation speed and gear ratio had significant effects on emitted sound level from the harvester. It was also observed that with increasing of distance from the driver's ear, the sound level was reduced due to the effects of ambient on noise damping. In position of the driver's ear, the sound levels were higher than the standard level of 85 dB(A) in all gears ratios and engine rotation speed. Therefore, the machine operator must use ear protection and the machine manufacturers should reduce the intensity of sound which emitted to the driver cabin.