Vibration tests on five agricultural tractors with increasingly efficient vibration control systems under normal working conditions

The investigation involved five agricultural tractors with increasingly efficient vibration control systems. Tri-axial frequency-weighted acceleration values were acquired on the seat surface and on the cabin floor, together with the running speed values. Measurements were carried out under normal working conditions. Results indicate that during ploughing and harrowing the axis determining the exposure risk for the operator is generally the transversal one, due to the roll effect. Differently, during translations on farm roads, the axis determining the exposure risk is the vertical one. The acceleration values determining the risk for the driver during plowing at 5 ÷ 7 km/h are high (0.86 ÷ 1.15 m/s) and always higher than the daily exposure action value defined in the European Directive 2002/44/CE (0.5 m/s). During harrowing at 2 km/h the acceleration values are quite low (0.23 ÷ 0.38 m/s). During translation at 17 ÷ 19 km/h the acceleration values are in the range 0.31 ÷ 0.95 m/s depending on the surface roughness (asphalt, dirt or gravel). Based on the whole set of measurements, the SEAT values are in the range 0.4 ÷ 1.38. As regards the comparison between the tractors, an absolute ranking was not achieved since the performances strictly depend on the working conditions. Referring to the seats, the ranking showed the opposite trend to the one expected considering the seat technology.