A STUDY TO INVESTIGATE VIBRATION EXPOSURE AMONG ON ROAD TRACTOR VEHICLE DRIVERS by Chander Prakash
For being an agricultural country, over 60 percent of India’s land area is arable, contributes to 16 percent of GDP and employment of 65 percent of total workforce. All such contributions couldn’t be possible without modernization of agriculture by means of mechanized machinery such as tractors. On the contrary, tractors have been found to be a major source of occupational whole body vibration which may affect human ride comfort. So, present study has been undertaken to investigate occupational whole body vibration exposures among tractor drivers while performing on-road as well as in-field harrowing operation. Ten (10) male drivers having mean age 25.10±3.78 years, body mass 75.3±8.54 Kg, stature 1.548±0.01 meter and body mass index 31.43±3.48 Kg/m2 were considered for conducting experimental runs. A total of three hundred sixty (360) experiments were conducted. It has been found that majority of vibration exposure levels in vertical axis were found to be exceeding exposure action value (EAV) as recommended by ISO 2631-1 1997 under on-road operations at 1500 as well as 2000 RPM levels. However, such exposure levels were observed to be exceeding EAV level in x, y and z axes under harrowing operation at 1500 RPM. Moreover, exposure values found above than exposure limit value (ELV) at 2000 RPM. Consequently, postural variation also showed varying vibration responses among all the selected subjects under different experimental conditions. The daily exposure A(8) and daily dose (VDVexp) value were also exceeding ISO exposure limits which may lead to severe health disorders if exposed to such vibrations for long term. Although, 1/3 octave analysis depicted a dominant frequency range of 3.15-4 Hz among all the subjects under entire on-road experimentation. While, frequency about 10 Hz found to be dominant under harrowing operation at both 1500 and 2000 RPM levels. Hence, it has been concluded that tractors needed more
designing efforts in order to damp vibration levels. In addition to it, suitable working time might be planned for operating tractor for various applications accordingly so vibration levels remains up to ISO exposure limits.