Exposure to high level of vibrations encountered in driver’s cabin of heavy duty truck over extended time causes driver fatigue and leads to serious health disorders. In most of the current heavy duty trucks in India, absence of proper vibration isolation system for driver’s seat results in transmission of high levels of vibration to the driver. A proper seat isolation system, combined with proper cushioning of seat can considerably reduce vibration transmissibility to the driver. The work presented here addresses the problem of vibration levels in a heavy duty truck and proposes solution for reducing vibration transmissibility to driver seat by using isolation and cushioning system. Vibration levels on floor, driver’s seat and seat back of an existing truck were measured using tri-axial accelerometer and 9 channel spectrum analyzer. Measured vibration levels in the vertical direction were found to be exceeding comfortable level. Using a single degree of freedom dynamic system to simulate floor-seat configuration, stiffness and damping parameters for an isolation system were determined. Another model, a 2 degree of freedom system that considers the stiffness and damping characteristics of the seat cushion, was also used for refininged the design. Isolator stiffness and damping parameters calculated were able to reduce RMS acceleration and VDV on stiff seat by 46%. For flexible seat, 63% reduction vibration level was possible.
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