A comparison between two materials for head-clamping pads of olive tree shakers: first trials

Current international olive growing practices are helping production from emerging countries to rise thanks to their technological capabilities. This creates new market dynamics and, consequently, it becomes necessary for Mediterranean producers to preserve their competitiveness within the global market. Technological innovation aimed at increasing harvesting operation sustainability constitutes one of the most decisive points that allow enhancement of olive growing. Trunk shakers have been the systems that provide the best working performance, at the same time allowing working site rationalization. However, one of the most important requirements is to ensure accurate fitting between the harvesting system and the tree, in order to guarantee that the tree properly receives settled vibrations from the shaker, and to maximize fruit detachment, at the same time avoiding trunk damage. The aim of the present research was to analyse the dynamic response of the olive tree trunk to transmitted vibrations during mechanical harvesting in a new intensive orchard in Andalucia. In particular, two different materials for head-clamping pads were tested, vulcanized rubber and PVC granules included in a coat of resilient material, in order to assess the transmitted efficient vibration. Dynamic analysis was performed on trees of cultivars 'Arbequina' and 'Picual'. Data analysis showed that the calculated acceleration values along the y-axis of the trunk were always higher, followed by those calculated along the z-axis. The lowest values were those recorded along the x-axis. For both cultivars, mean resultant acceleration was higher using head-clamping pads made from vulcanized rubber. However, less trunk damage resulted from use of the PVC granule pad. More studies are still needed to better understand the influence of this new material on transmission of vibration to the tree trunk.