A conveyor is arranged to be mounted underneath a hopper bottom highway transportation truck which has two longitudinally spaced dump hoppers each with a bottom discharge opening to carry the discharged material to the side of the trailer from each of the hoppers in turn. The conveyor is thus carried between the bottom discharge openings so that it can be raised up between them during transport. From the mounting point at one side between the openings the conveyor is lowered so that its loading end is lowered and then the conveyor pivots to one side or the other so that its loading end is underneath the selected bottom discharge opening. The conveyor runs in a direction so that it lifts the material from the selected discharge opening upwardly to the mounting point at the one side for discharge to the side.
