2016 Volume 7 Issue 2 Pages 113-119
The increase of agricultural mechanization, especially hand tractors has been remarkably emerged in the last decade. It is known as well that agricultural mechanization not only facilitated timely completion of operations but also increased production, labor savings, energy efficiency, productivity, and profitability. With high degree of hand tractor use, providing a safe and comfortable working environment to operators became an important consideration, specifically vibration that is a main cause of early fatigues. In this study focus on measuring translational acceleration and rotational angular velocity at various locations of hand-tractor under stationary and driving modes. Root-mean-squares (RMS) and power-spectrum-density (PSD) were used to investigate vibration magnitude and dominant frequencies, and effective measurements were finally suggested. Results showed that under stationary mode largest vibration acceleration appeared at handgrip in vertical axis of about 8.5m/s2 followed by engine top, gearbox and chassis, respectively. In driving mode, the main vibration magnitude occurs in vertical axis at about 11.8 m/s2. Within 50Hz frequencies, predominant acceleration occurred in longitudinal axis at about 10Hz frequencies at first peak and about 18Hz frequencies at next peak at engine top. Whereas, at handgrip predominant acceleration appeared hugely in vertical axis at about 10Hz frequencies, and at the same frequency was found in pitch axis of rotational angular velocity under stationary mode. However, it appears clearly at about 9Hz frequencies in vertical axis in driving mode. Both conditions, vibration exposures are much higher than that in health risk limitation standard that operators should be prevented effectively; otherwise, to suffer from early fatigue.
