The invention relates to a device for crumbling root crops into substantially equal sized pieces, comprising: a main frame having an inlet side and an outlet side; a root crop supply at the inlet side; at least one crumbling shaft rotatable supported in the main frame, the crumbling shaft being provided with a plurality of curved hooks, which are curved into a direction of rotation of the crumbling shaft; and a non-rotating cutting rake having a plurality of protrusions and recesses and forming a counter blade for the hooks, wherein the hooks are arranged for interlaced movement with said recesses of the non-rotating rake. The invention moreover concerns a system and a corresponding method.