Bale forming apparatus with a bale forming device comprising - a plurality of rotatably mounted bale forming rollers (10.1,..., 10.6, 11.1,..., 11.6, 23.1,..., 24.2, 8.1, 8.2) and - a first roller holding device, wherein the bale forming device is arranged to form a round-cylindrical bale in a bale forming chamber which - is at least temporarily delimited by the forming rollers (10.1,..., 10.6, 11.1,..., 11.6, 23.1,..., 24.2, 8.1, 8.2) of the plurality and - is changeable between a first chamber size and at least one further chamber size being larger than the first size, wherein - at least one moveable bale forming roller (10.1,..., 10.5) and at least one further bale forming roller (10.6) belong to a first set and - at least one other bale forming roller (11.1,..., 11.6) belongs to a second set, wherein the bale forming chamber is positioned between the two sets (10, 11), wherein the or every moveable bale forming roller (10.1,..., 10.5, 11.1,..., 11.5) is moveable in a direction perpendicular to its rotating axis into at least two different roller positions, and wherein the bale forming rollers (10.1,..., 10.6) of the first set are mounted in a sequence at the first roller holding device, characterized in that the bale forming device further comprises a connecting slide, wherein the connecting slide is moveable along the sequence of the bale forming rollers (10.1,..., 10.6) of the first set - into a first sliding position and - into at least one further sliding position with respect to the first set, wherein the bale forming chamber - has the first chamber size when the connecting slide is in the first sliding position and - has the or one larger further chamber size when the connecting slide is in the or one further sliding position, wherein the connecting slide connects in every sliding position - one bale forming roller (10.1,..., 10.6) of the first set with - one bale forming roller (11.1,..., 11.6) of the second set, wherein in every sliding position the two connected bale forming rollers (10.1, 11.1,..., 11.5) contribute to delimiting the bale forming chamber, wherein the connecting slide being in the first sliding position connects - the or one moveable bale forming roller (10.1) of the first set with - one bale forming roller (11.1) of the second set, wherein the connecting slide being in the or every further sliding position connects - the or one further bale forming roller (10.2,..., 10.6) of the first set with - one bale forming roller (11.2,..., 11.6) of the second set, wherein the further bale forming roller (10.2,..., 10.6) of the first set which is connected by the connecting slide being in the further sliding position is spaced apart from the bale forming chamber, thereby does not contribute to delimiting the bale forming chamber, when the connecting slide is in the first sliding position. - a plurality of rotatably mounted bale forming rollers (10.1,..., 10.6, 11.1,..., 11.6, 23.1,..., 24.2, 8.1, 8.2) and - a first roller holding device, - is at least temporarily delimited by the forming rollers (10.1,..., 10.6, 11.1,..., 11.6, 23.1,..., 24.2, 8.1, 8.2) of the plurality and - is changeable between a first chamber size and at least one further chamber size being larger than the first size, - at least one moveable bale forming roller (10.1,..., 10.5) and at least one further bale forming roller (10.6) belong to a first set and - at least one other bale forming roller (11.1,..., 11.6) belongs to a second set, - into a first sliding position and - into at least one further sliding position - has the first chamber size when the connecting slide is in the first sliding position and - has the or one larger further chamber size when the connecting slide is in the or one further sliding position, - one bale forming roller (10.1,..., 10.6) of the first set with - one bale forming roller (11.1,..., 11.6) of the second set, - the or one moveable bale forming roller (10.1) of the first set with - one bale forming roller (11.1) of the second set, - the or one further bale forming roller (10.2,..., 10.6) of the first set with - one bale forming roller (11.2,..., 11.6) of the second set,