As the Patent ES9301070 discloses, the tank generally used is a V shaped container with a rounded bottom, and usually the diameter of the bottom is wider than the diameter of the circle described by the spirals of the cutting roller when they rotate. Those tanks, currently used to chop animal feed, have the main disadvantage of accumulating the product in the centre of the tank, i.e. between the external diameter of the central blades and the rounded bottom of the tank, which means the shafts of the chopping mechanisms, i.e. the chopping spiral screws, have to generate quite a high operating torque, and sometimes this strain can even buckle them