This invention relates to a supply system (7) for a combine harvester (100), the supply system including a housing and a conveyor assembly (101) arranged in the housing, and the conveyor assembly including lateral support arms, and movable toothed belts which are guided by gear discs The toothed pulleys are mounted on a drive shaft in the vicinity of an outlet section of the housing and on a conveyor near an inlet section of the housing. The toothed pulleys are mounted on a drive shaft (22) which is located near an outlet section (15) of the housing and on a conveyor shaft (26) in the vicinity of an inlet section (14). The conveyor assembly is provided with a first and a second tensioning mechanism, the first mechanism being configured to press the conveyor shaft forward
