The driver responses to the vibration of tractor
Whole body vibration is one of the main causes of musculoskeletal disorders of drivers. The purpose of this study was to investigate the allowable exposer time, the care limit and driver response to the vibrations of the seat of ITM 475 Tractor. A three-way accelerometer was used to carry out the tests in the present study based on the ISO 2631-1 international vibration standard. The studied factors were engine rotational speed at three levels of 1000, 1500 and 2000 rpms, gear ratio (1, 2 and 3) and road at two level, dirt and asphalt. The obtained data were analyzed through factorial experiment based on completely randomized design with 18 treatments and three replications. The results showed that effects of the main factors and those of their interactions on the total vibration emitted from the tractor seat were significant at 1% probability level. The highest amount of whole body vibration on a dirt road was 1.49 m s-2 which took placed at 2000 rpm and the 3rd gear ratio. Consequently, the minimum exposure time and the driver care time limit were 1.16 and 0.14 h, respectively. This treatment was in very uncomfortable range. The maximum whole body vibration for 8 h ride on ITM 475 was 0.85 m s-2. Therefore, it is necessary to reduce whole body vibration of the studied tractor via designing a cabin and/or a new seat.