Influence on operator's health of hand-transmitted vibrations from handles of a single-axle tractor.

The operators of the single-axle tractors are especially exposed to hand-arm transmitted vibrations. These vibrations can cause the complex of vascular, neurological and musculoskeletal disorders, collectively named hand-arm vibration syndrome. Among these, the most common disorder is vibration-induced white finger (Raynaud's phenomenon). The vibration levels were measured in three tractor's working conditions, namely idling, transportation and soil tillage. The vibration level on the handles was measured and analysed and the frequency spectra for the chosen working conditions were obtained. The frequency-weighted acceleration, given in m/s2, was calculated and the obtained values are graphically presented. The measured vibration levels are then discussed with regard to the operator's daily exposure limits recommended by the ISO 5349. The vibration levels were much higher in the x and y directions than the z-direction in all working conditions. The vibration total values in idling, transportation and soil tillage were 3.37, 8.37 and 9.62 m/s2, respectively. Results showed that the 10% of workers are exposed to a risk of vibration-induced white finger disorder of the hands after relatively short periods (3-4 years), if the tractor is used 8 hour per day in soil tillage and transportation at full load. Considering the criteria of the ISO 5349, the daily working time with the single-axle tractor should be limited in order to protect the operator and work schedules should be arranged to include vibration-free periods.