Abstract: According to the present invention an agricultural machine for forming a round bale of windrowed fibrous material comprises a displaceable chassis carrying spaced apart side plates defining the width of a bale-forming chamber, a pick-up device located towards a forward end of the chassis and adapted to pick-up fibrous material from the ground and to discharge the fibrous material on to a carrying surface, which extends generally horizontally, of a first, fixed position belt conveyor defining the bottom of the chamber, and having a head end adjacent the pick-up device and a return end remote from the pick-up device, and serving to carry the fibrous material away from the pick-up device, and a plurality of additional belt conveyors each having an active surface adapted to co-operate with the carrying surface of the first, fixed position belt conveyor in the forming of a bale by the rolling of fibrous material, at least one of the additional belt conveyors being movable by having one end pivotably mounted, so th