A cleaning system for corn cobs incorporating a conveyor system providing a capability for positively removing or cleaning other crop residue from the cobs, which is adapted to be towed by a harvester; to be incorporated with a cob collecting device; and which can be adjustable for varying corn varieties, conditions and the like. The conveyor system includes at least one enclosed inclined conveyor for carrying a flow of the crop residue upwardly and propelling the flow into a space, while a flow of air is directed downwardly along the conveyor to remove other residue material from the cobs. Another flow of air is optionally directed downwardly through the space for removing additional material other than cobs, and at least one aspect of the system can be adjusted for relatively varying the air flows to adapt the system for a variety of conditions.