Descriptive analysis of combine cabin vibrations and their effect on the human body

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Descriptive analysis of combine cabin vibrations and their effect on the human body

Hostens, I. / Ramon, H.

All on- and off-road vehicles are exposed to vibrations caused by unevenness of road or soil profile, moving elements within the machine or implements. A higher prevalence of low back pain is found in drivers of off-road machinery than in other drivers. In this study, significantly higher levels of low-frequency vibrations are found in the cabin of a combine, driving at high speed (20 km/h) on a concrete surface, compared to driving slower on field road. Comfort values indicate that injury can result from long-term driving on the field as well as on a concrete road. As seats with suspension systems are the main transmission paths of vibration towards the spine of the driver, their vibration attenuating characteristics play an important role in comfort assessment. The resonant frequency of seats with passive suspension system used in agricultural machinery, lies in the low-frequency range most excited in agricultural machinery. A seat with air suspension is found to attenuate better frequencies above 4 Hz and provide more comfort to the driver than a seat with a mechanical suspension. The study and comparison of two commonly used combine seats with suspension system show the main resonant frequency around 2 Hz for both mechanical- and air-suspended seat. The air-suspended seat provides more vibration attenuation at frequencies above 4 Hz, and more comfort as indicated by the seat values. Above the frequency range 7-9 Hz, the seat cushions provide extra vibration attenuation. Low-frequency vibration is much more present in heavy off-road machinery than in other transportation means and the resonant frequency of nowadays-used seats with passive suspension system lies in the low-frequency area. In future, low-frequency vibration (0.5-5 Hz) need to be given more weight in seat or cabin suspension design and comfort assessment.