Abstract: A cleaning or treating machine, particularly but not necessarily exclusively for cleaning newly formed aluminum beverage cans, has a belt for conveying items placed thereon through various stages of a washing cycle and a hold-down conveyor overlying the cans for preventing them from tipping. The hold-down conveyor has stiffening means extending thereacross and is trained over rolls or drums which are specially formed to accommodate the stiffening means. The conveyor is longitudinally supported by having rollers projecting from its longitudinal edges and which ride on tracks.