This study involves designing a branch shaker operating with an air compressor and its application for harvesting olives. Fruit detachment force (FDF) and fruit weight (W) were measured and hence the changes in the percentage of removed fruits with shaking were determined at different maturity times. During the harvesting season, two sets of experiments were conducted to test the shaker in the removal of Halhali cultivar olives (Olea europaea L.) with and without application of abscission chemical (ethrel). Experiments were also carried out to determine the effect of the chemical on fruit detachment force, fruit weight, and mechanical harvesting efficiency. Shaking tests showed that the removal percentage of olives without chemical application was lower than 50%. However, application of abscission chemical reduced the FDF/W ratio and thus increased the removal percentage of olives. The lowest fruit detachment force and the highest fruit removal (96%) were obtained by employing a frequency of 24 Hz and 12.5 mL/L concentration of abscission chemical with constant amplitude of 60 mm. Moreover, it was found that the fruit removal efficiency increases with decreasing olive detachment forces. (c) 2005 Elsevier Ltd. All rights reserved.