- Metal-Fach has three stubble cultivator models with 300 mm spaced prongs. The machines feature from 10 to 14 working teeth, depending on the model. Each model has a different working width, from 3 to 4.2 metres. The U490 is the smallest model in the range, complete with 7 discs and 10 prongs. The available working width is 3 metres. The required minimum tractor output ranges from 120 to 190 HP. T...he U490/1 version has 12 teeth and 8 discs. The working range here is 3.5 m. Since this version is larger, it requires a tractor rated at 130 to 210 HP. Both model versions have the working depth range of 5 to 30 cm. Both model versions feature rigid suspended frames. The largest version of the Metal-Fach stubble cultivators comes with 14 prongs and 10 discs. Metal-Fach designers have applied a hydraulically-folded suspended frame in the machine. The cultivator’s working range may reach an astounding 4.2 m. The machine’s power demand is very high, from 150 to 240 HP. All machine versions feature hydraulic working depth control.