Contribution for the definition of a vibrations standard for Big Self-propelled Harvesting Machines

Vibrations are usually an ergonomic parameter poorly investigated in agriculture, even if it influences remarkably the health and the comfort quality of the operators. The dedicated legislation is normally devoted to measure the daily exposure of the worker. The standards can be classified considering as the subject investigated (evaluating his/her whole-body and hand-arm exposures), as the agricultural machinery more directly. The Big Self-propelled Harvesting Machines (BSHM) still suffer of a lack of dedicated standards. Normally, the BSHM are used for short periods during the year, corresponding with the harvesting of cereals and other crops. The operator job results in this case very haeavy, in terms of daily hours worked (till to 10-12), and also for the high level of care devoted to the machine driving. Vibrations often represent a factor of great disturb and producing much fatigue. To investigate the problem, the vibration levels on the seat and on the steering-wheel on various BSHM (such as combine harvesters, forage harvesters, tomate and sugar-beet harvesters, mixer wagons, etc.) were measured and recorded. Due to the poorly defined test conditions, the tests were previously carried out with reference to EN 1553 standard. So, the examined machines were stationary, no product was present, the engine was settled at the rated speed, and all the transmissions and moving parts were working. In such conditions, no dramatically high vibration levels were recorded, apart some few cases. Nevertheless, seems that in some specific situations the limit established by the Machine Directive could be considered rather high, provided that this standard has to be applied to a wide variety of machines, not only those used in the agricultural field. In fact, a different scaling of the limits is under investigation. In any case, the test machine settlement do not generally simulate well the real field conditions, so that a further investigation has been carried out, in order to compare, on the same or very similar machines, the level obtained in stationary conditions and those recorded into the field, carrying out the normal operations. In several cases, significant differences were found: on a tomato harvester, in particular, the vibrations levels were found much more higher into the field, as at the driver’s place (on the seat and also on the steering wheel), as on the platform where some other operators are standing for the tomato selection job. More investigations are needed, in order to point out, for a wide range of BSHM, the field vibrations levels in different operation conditions, to define limits able to suitably assure comfortable working conditions at the operators.