US Patent 7540136 Field chopper and press rolls

The invention relates to a field chopper having at least one rotatable lower rough-press roll and at least one rotatable upper rough-press roll. Between the rough-press rolls crop is pressed and fed to a chopping drum where blades chop the crop. A space is defined down stream of the moveable rough-pressing roll between the chopping drum, the stream of pressed crop and the movable rough-press roll. Located in this space is a pressing element that acts on the pressed crop and which exerts a rough-pressing effect on the pressed crop downstream of the movable rough-press roll and upstream of the chopping drum.