Three-axial Evaluation of Whole-Body Vibration in Agricultural Telehandlers: The Effects of an Active Cab-suspension System

Agricultural and earth-moving machinery operators are particularly exposed to whole body vibration (WBV), which has severe effects on health and affects comfort and performance. Few studies have investigated vibrational safety and comfort issues in telescopic handlers. These vehicles are widespread in many off-road applications--such as construction, agriculture and mining--used to handle loads and to lift persons and equipment. This study investigated the effects of an active hydro-pneumatic cabsuspension system fitted to a telehandler on a driver's vibration exposure along the x-, y- and z-axes, through both objective and subjective assessments. Sixteen healthy professional telehandler drivers took part in the study. Objective measurements were acquired at the operator's seat, and subjective ratings were taken while participants drove the telehandler with either a deactivated or activated suspension system at 12 kph on an ISO 5008 smooth track. The results showed that the activation of the cab-suspension system reduced the root-mean-square acceleration along the x- and z-axes. (p=.038 and p=.000, respectively). Moreover, the frequency analysis showed a reduction in the acceleration along the z-axis in the range of 2-25 Hz (p<.05 for all comparisons); in particular, the acceleration was reduced by 50% in the acceleration in the higher frequency range (4-20 Hz) along the z-axis.). A reduction in the vibration intensity was perceived by the participants along the y- and z-axes. (p=.009 and p=.003, respectively). Implications for the future development of suspension systems are discussed.