The harvesting machine (1) has a belt drive (11) which is directly or indirectly driven by internal combustion engine (10). The belt drive has drive pulley (13), driven pulley (15), and a belt tensioning device (18) which is associated with drive pulley and driven pulley. The belt clamping force of belt tensioning device is adjusted by a control device (21) based on nature and condition of crop and slippage of belt drive.
