mechanical harvesters straddle the tree row the tree goes inside them- they have heavy counterweights on top of two columns, which are driven at variable speeds. as these weights spin they cause the columns to rotate. attached to the columns are hundreds of picking rods, which vibrate and oscillate as the weights on top rotate.the vibration of these rods through the trees is what picks the coffee off the tree. below the columns are "fish plates" which are angled segments of polycarbonate sheet attached to springs.