Design, construction and evaluation of a portable limb shaker for almond tree

The cost of picking fruit is probably the major factor in determining whether or not there will be an economically successful season for most farmers. Manual harvesting of fruit accounts for 30 to 60% of the total production costs. The aim of the present study was to design, construct and evaluate a portable limb shaker for almond tree. The shaker was powered by a 2-stroke (spark ignition) engine. A centrifugal clutch along with a gearbox was used in conjunction with a slider-crank mechanism to transmit power to a limb through a boom and C- shaped clamp. To evaluate the machine performance, a factorial experiment with complete randomized design in three replications was conducted, the factors being shaking frequency (10, 13 and 15 Hz), shaking duration (5 and 10 s) and almond cultivars (Azar, Harir and a kind of local almond). To calculate the ratio of fruit detachment force (F) to its weight (W), appropriate measurements were made. Also, the geometric mean diameter of the fruits was determined at different stages of maturity. Analysis of variance and comparison of means by Duncanʹs multiple range test showed that the effects of shaking frequency and shaking time on fruit detachment were significant, while the effect of almond cultivars and their interactions were not significant (p<0.01). The number of fruits detached increased by increasing the shaking frequency. Maximum number of fruits detachment (97.99%) was obtained by applying 15 Hz shaking frequency. Also the number of fruits detached increased by increasing the shaking duration. F/W ratio decreased with maturity, while the geometric mean diameter increased with maturity.