Evaluation of Quality of Harvest and Mechanical Aspects Related to Beater Adjustments in Mechanical Grape Harvesting

Abstract

<abstract> <bold><sc>Abstract. </sc></bold>Research was conducted on a trailed grape harvester that allows independent adjustment of frequency and amplitude of the beaters’ movement. The frequency ranged from 300 to 540 beats min^-1, while the amplitude range was 30 to 90 mm and was managed by the operator using an electromechanical control. The objective of this research was to evaluate the effects of these adjustments on the quality and productivity performances of a grape harvester. Harvest quality was evaluated by checking the condition of the detached grapes, the level of plant defoliation, and the amount of visible and concealed losses. The mechanical action of the harvester was evaluated at the moment of grape detachment, measuring the stresses transmitted by the beating system. The dynamic effects of adjustment of the beater movement amplitude were similar to those of the frequency adjustment, affecting the number of stresses, the transmitted power and displacement caused, but not the acceleration values. Compared to frequency control, adjustment of the beater movement amplitude also provided greater possibilities to use a higher forward ground speed. The variation in beater movement amplitude proved to be an adjustment in many ways similar to the frequency variation that can be used to improve grape detachment or increase grape harvester productivity. In the case of only varying the beater movement amplitude from 30 to 90 mm, the harvesting losses were reduced from 7.9% to 5.1%.