A feeder apparatus for a combine harvester, for transporting crops from a combine header towards a threshing and cleaning installation of the combine harvester, the feeder apparatus comprising a feeder housing having an inlet section and an outlet section, and further comprising a conveyor assembly mounted in the housing, the conveyor assembly comprising: • a frame comprising a first and a second support arm (18,19), the support arms being mutually parallel and extending between the inlet and outlet section of the housing, the frame being pivotable with respect to the feeder housing, about a pivot axis that coincides with the rotation axis of a drive shaft, • the drive shaft being rotatably mounted between the first and second support arms, proximate the outlet section of the feeder housing, with at least two sprocket wheels mounted on the drive shaft, • a conveyor shaft rotatably mounted between the first and second support arms (18,19), proximate the inlet section of the feeder housing, with at least two sprocket wheels mounted on the conveyor shaft, at positions corresponding to the sprocket wheels on the drive shaft, • toothed belts arranged around each pair of sprocket wheels (25,28) on the drive shaft and on the conveyor shaft, the teeth of the belts engaging with the sprockets of the sprocket wheels, so that rotation of the drive shaft actuates movement of the belts, • transversal crop transporting slats attached to each pair of adjacent belts, wherein the conveyor assembly further comprises: • a first belt tensioning mechanism comprising a pair of first tensioning arms configured to be able to push the conveyor shaft forward with respect to the support arms (18,19), • a second tensioning mechanism comprising a pair of second tensioning arms carrying between them and above the support arms, a tensioning axle provided with tensioning rolls, the belts running over the tensioning rolls, the second tensioning arms being spring-operated in a manner to be able to push the tensioning axle upwards with respect to the support arms (18,19). • a frame comprising a first and a second support arm (18,19), the support arms being mutually parallel and extending between the inlet and outlet section of the housing, the frame being pivotable with respect to the feeder housing, about a pivot axis that coincides with the rotation axis of a drive shaft, • the drive shaft being rotatably mounted between the first and second support arms, proximate the outlet section of the feeder housing, with at least two sprocket wheels mounted on the drive shaft, • a conveyor shaft rotatably mounted between the first and second support arms (18,19), proximate the inlet section of the feeder housing, with at least two sprocket wheels mounted on the conveyor shaft, at positions corresponding to the sprocket wheels on the drive shaft, • toothed belts arranged around each pair of sprocket wheels (25,28) on the drive shaft and on the conveyor shaft, the teeth of the belts engaging with the sprockets of the sprocket wheels, so that rotation of the drive shaft actuates movement of the belts, • transversal crop transporting slats attached to each pair of adjacent belts, • a first belt tensioning mechanism comprising a pair of first tensioning arms configured to be able to push the conveyor shaft forward with respect to the support arms (18,19), • a second tensioning mechanism comprising a pair of second tensioning arms carrying between them and above the support arms, a tensioning axle provided with tensioning rolls, the belts running over the tensioning rolls, the second tensioning arms being spring-operated in a manner to be able to push the tensioning axle upwards with respect to the support arms (18,19).