A modular system comprising at least one continuously variable transmission (31, 31') for driving at least one working unit of a harvesting machine, wherein the at least one continuously variable transmission (31, 31') comprises the following basic components: - a drive pulley set and a driven pulley set which each have two conical adjustable pulleys (36a, 36b; 37a, 37b), which are respectively rotatable about an axis of rotation (39a, 39b), - torque-transmitting components on which the drive pulley set and the driven pulley set are disposed, wherein the torque-transmitting components are respectively a drive shaft (40, 47) configured as a hollow shaft (40, 47), a hub (41, 48) which is respectively connected to the hollow shaft (40, 47) so as to be fixed against rotation and axially displaceably disposed on the respective hollow shaft (40, 47) along the axis of rotation (39a, 39b), and - a hollow cylindrical transmission section which is connected to the respectively hollow shaft (40, 47) so as to be fixed against rotation, - wherein a respective at least one adjustable pulley (36b, 37b) is axially displaceably disposed on the respectively hollow shaft (40, 47) of the drive pulley set and of the driven pulley set, wherein, by means of a variation in the basic components, at least two transmission modules (30, 30') can be constructed which form different continuously variable transmissions (31, 31'), wherein two of the basic components (36a, 36b, 37a, 37b, 38) of the at least two transmission modules (30, 30') are identical in construction for the purposes of power transmission, characterized in that the adjustable pulleys (36a, 36b, 37a, 37b) of the drive pulley set and of the driven pulley set of the at least two transmission modules (30, 30') have a structurally identical construction, so that the geometrical shape of the adjustable pulleys (36a, 36b, 37a, 37b) which are used within one of the transmission modules (30, 30') and are used universally for the at least two transmission modules (30, 30') is identical, and in that the hollow cylindrical transmission sections on the drive side and the driven side of the at least two transmission modules (30, 30') are identical in construction, wherein the hollow cylindrical transmission sections on the drive side and the driven side are configured so as to receive the respective adjustable pulley (36a, 37a) of the drive pulley set as well as of the driven pulley set which are respectively immovably disposed on the respective hollow shaft (40, 47). - a drive pulley set and a driven pulley set which each have two conical adjustable pulleys (36a, 36b; 37a, 37b), which are respectively rotatable about an axis of rotation (39a, 39b), - torque-transmitting components on which the drive pulley set and the driven pulley set are disposed, wherein the torque-transmitting components are respectively a drive shaft (40, 47) configured as a hollow shaft (40, 47), a hub (41, 48) which is respectively connected to the hollow shaft (40, 47) so as to be fixed against rotation and axially displaceably disposed on the respective hollow shaft (40, 47) along the axis of rotation (39a, 39b), and - a hollow cylindrical transmission section which is connected to the respectively hollow shaft (40, 47) so as to be fixed against rotation, - wherein a respective at least one adjustable pulley (36b, 37b) is axially displaceably disposed on the respectively hollow shaft (40, 47) of the drive pulley set and of the driven pulley set, - wherein a respective at least one adjustable pulley (36b, 37b) is axially displaceably disposed on the respectively hollow shaft (40, 47) of the drive pulley set and of the driven pulley set,