Mechanical harvesting of apricots

An inertia type limb shaker hydraulically, powered and driven by the tractor power take-off, was designed and constructed for the mechanical harvesting of apricots. The study included some properties of apricot fruits, the apparent stiffness with respect to limb diameter, the time needed to shake a limb, optimum frequency and amplitude to obtain maximum fruit removal with minimum reactive force, limb amplitude, the effects of limb and tree properties on the fruit removal percentage, fruit damage, harvesting rate of the shaker; and comparisons with other harvesting methods. Harvesting rate was calculated by weighing both the harvested and unharvested apricot fruits. Fruit damage was evaluated from the modulus of elasticity of apricot fruit before and after harvesting. In order to study fruit damage, the effect of surface of different materials were examined: plastic canvas; nylon; and sponge. In the tests, the limbs were shaken at 20, 30, 40, 50 and 60 mm amplitude of the connecting rod attached to the crankshaft and 10, 15 and 20 Hz frequencies for optimum shaking time. The results were analysed according to the maximum fruit removal percentage. The limb amplitude was calculated using the apparent stiffness, masses of shaking mechanism, shaker arm and reduced mass of limb. Shaking time, frequency and amplitude for a limb were found as 5 s, 15 Hz, and 40 mm, respectively. Limb position, limb length and tree size affected the fruit removal percentage at the 5% significance level. The least fruit damage was obtained with the plastic canvas catching surface. The time required to harvest an apricot tree by hand and by traditional and mechanical harvesting methods were 400, 20, and 6 min, respectively. The inertia type limb shaker showed great promise and did not cause any damage to the limb and bark. (C) 2003 Silsoe Research Institute. All rights reserved Published by Elsevier Science Ltd.