Vibrazioni sulle grandi operatrici agricole semoventi : indicazioni per un progresso tecnico delle norme

The Large Self-propelled Agricultural Machines (LSAMs) suffer for a lack of dedicated standardization on vibrations. For the complexity in driving LSAMs, both on the field and on the road, operators are particularly exposed to vibrations, due to remarkable phyiscal and psycological stress they cause. For this, vibration levels of various LSAMs working on cereals and vegetables crops were measured, with the aim to obtain a specific risk evaluation. The values were ascertained both on the driver’s seat and on the steering wheel, following what stated in EN 1553: all the working accessories running, rated engine speed, no load, stationary vehicle. The limits provided by the Machine Directive were considered: 0.5 m/s² (whole body) and 2.5 m/s² (hand-arm); the measurements were executed in accordance with ISO 2631/1 (seat) and ISO 5349 (steering wheel). In general, the examined LSAMs did not show high vibration values: nevertheless, some doubts are arisen about the suitability of the limits provided by the Machine Directive in order to conveniently cover the particularly stressing working situations on LSAMs. Therefore the obtained results have been compared with possible reduction of 10 %, 30 % and 50 % of the present limits. Considering the results of this study, a reduction between 30 % and 50 % could be proposed for the seat (new lower limit: 0,30 m/s²), while a decrease of 30 % could be applied for the steering wheel (new limit: 1,75 m/s²).