2008 Volume 43 Issue 3 Pages 117-125
Mechanical apple harvesting experiments were conducted using a backpack shaker and a tractor-mounted shaker. The shaken fruits were collected by a 2.7m by 2.7m catching frame laid on the ground. The resistance force required to remove a fruit from its bearing shoot and the storability of harvested fruits were investigated. The main results were as follows :
(1) When a fruit was pulled perpendicular to the peduncle, the removal force was 1/5 of that when pulled parallel to it. All fruits pulled perpendicularly retained their peduncles.
(2) In the vibration test, frequencies of at least 6.7, 5.0, 3.3, and 3.3Hz were needed in amplitudes of 1, 2, 3, and 4cm respectively in order to shake off apples from the bearing shoots within 3 seconds.
(3) The percentage of fruits removed from a limb from the point of attachment of the shaker clamp to the tip was 90%. The catching frame collected nearly 100% of the shaken fruits.
(4) The amplitude of limb movement produced by the backpack shaker was 1.4 to 3.3cm and that by the tractor-mounted shaker was 3.8 to 3.9cm.
(5) The shaker-harvested fruits had bruises, cuts and punctures. Sixty% of the fruits showed no skin damage after storage for 2.5 months.
(6) Fruits dropped from a height of 2m onto urethane foam 10cm thick were not damaged.
