PM—Power and Machinery: Innovative Systems to reduce Vibrations on Agricultural Tractors: Comparative Analysis of Acceleration transmitted through the Driving Seat

The vibration transmitted through the seat of a four-wheel drive tractor, developing 92 kW at the p.t.o., and equipped with front suspension axle and shock absorber for the implement, were measured and analysed according to the ISO standard. Several tests were carried out in different conditions considering: type of operation (transfer with and without mounted implement, ploughing, harrowing); type of track (conglomerate bituminous track, macadam dirt track, country lane); connected and disconnected suspension and/or shock absorber and a range of forward speeds. In the transfer test on track, the vehicle suspension caused an average acceleration reduction of about 15%, and it could reach 30%. The shock absorber displayed a variable behaviour depending on the test condition; it could cause both attenuation and amplification, although the combination with the suspension often involves a high average reduction in acceleration (24%). In the soil tillage tests, the suspension could cause a substantial reduction in acceleration (up to 36%), but only in some conditions. With reference to the benefit for the driver due to the acceleration attenuation involved by the systems, it is important to note that, during soil tillage, the vehicle suspension could compromise the driver's health through an increase in daily exposure time of about 50% during ploughing and of more than 100% during harrowing.