Measurement of Mechanical Stresses Transmitted by Grape Harvesters.

The research aims to analyze the stresses transmitted during the interception and transport of grape by mechanical tools of grape harvesters. The aim is to characterize mechanically an overlooked feature of the harvesters, identifying the most critical points in terms of mechanical stress on the product. The research has tested the main horizontal shaking machines, trailed and self-propelled, operating in Italy. The tests were carried out on Lambrusco Grasparossa vines grown on level land. The vineyard was trained to spurred cordon, with a plant distance of 1.2 m by 2.5 m. The impact on machine parts, from the moment the product was detached until it was unloaded into the hopper, was measured using an instrumented sphere. Each grape harvester has been used in real work condition by putting the sphere in the grape flow. The trial allowed to trace the path of the grape inside the grape harvester, showing significant differences between the two types of machines (self-propelled and trailed) within the same type. It appears that the interception and transport equipment can worsen the integrity and quality of the grapes harvested mechanically.