an oscillating sorting conveyor is adapted for separating whole berries of wine grapes from undesirable components such as “ shot berries ” , stems , raisins , leaf material , bugs , pebbles and the like . the sorter deploys a downward tilting trough that is driven to oscillate . a screen is disposed at the bottom of the trough such that whole berries are conveyed over the screen while the undesirable components pass through the screen the preferred embodiment of the screen has a non - uniform cross - section to improve the efficiency of removal the undesirable components without clogging or requiring constant maintenance .