人間工学ジャーナル
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概要

Effect of Tractor Seat Suspension Parameters on Vibration Exposure

Pradhan RR*, Behera D, Goel AK, Mohanty SK

India is the largest manufacturer of farm equipment like tractor, harvester and tiller. It accounts one third global tractor production. Tractor sale in the country is expected to increase 11-13 per cent in the financial year 2019 while the tractor industry is expected to grow at 8-10 per cent during 2019-23. In the country, the agricultural tractors used for different farm operations starting from land preparation up to harvesting and transportation of agricultural products. Due to this various types of random vibrations, generated from terrain and tractor engine, is transmitted to the operator through seat suspension. Most of the tractors available in India, are attached with a passive type vertical seat suspension which is found to decrease vibration in vertical direction. Many research works have been done in optimisation/modification of the seat suspension parameters alone and development of new seat suspension. But none of them optimize the seat suspension parameters in combination. Hence, the following study was conducted to determine the optimized value of seat suspension parameters for which the vibration transmitted to the operator could be minimum. For this a seat suspension model was developed in AMESim software. The model requires input signal which was tractor seat mounting vibration data and gives the model output data as seat cushion vibration. When the model output data was compared with the test result data for the same vibration input, it was found to have 77.93 per cent correlation. The optimization result of seat suspension parameters alone, spring stiffness of 12000 N/m damping coefficient of 4225 N.s/m was observed to have minimum vibration. While optimizing both the suspension parameters, the combination of 3000 N/m and 2225 N.s/m was found to have minimum vibration. However, it was only 10.79 per cent less than the measured vibration value which might not be an economical decision though there is reduction in vibration.