The design of bunch shaker and the date fruit detachment force

Abstract

In this work, the design and construction of a tractor-mounted shaker used for the removal of date fruits from the bunch is presented. The dynamic force developed by this shaker is calculated and the tensile force required to detach the date fruit at subsequent stages of fruit maturity is measured with the prospect of relating the two forces. Such a relation would facilitate the design of shaker stroke and frequency which would develop a dynamic force equivalent to the detachment force requirement for any type of date variety. The experimental results confirmed that the detachment force decreased significantly with the progress of fruit maturity. The average tensile detachment force at the final stage of fruit maturity was 6.8 N which is 20% of the average tensile detachment force at the first stage of fruit maturity (33.4 N). However, the dynamic force developed by the bunch shaker at different shaking frequencies, which ranged from 0.42 N to 2.68 N, is much lower than the tensile detachment force. This implies that dates removal from the bunch by a bunch shaker cannot be attributed to the development of a dynamic force which exceeds the tensile detachment force requirement. Consequently, the tensile fruit detachment force cannot be utilized as a criterion for the design of a date bunch shaker.