COARSE MATERIAL CRUSHER

PROBLEM TO BE SOLVED: To replace cutting blades when they are partially worn or damaged to extend the service life of the whole lower crushing roller by attachably and detachably fitting main cutting blades to cutting and crushing blades near collection parts formed between screw crushing blades. SOLUTION: A pair of upper crushing rollers 3, 4 in parallel and a lower crushing roller 10 positioned thereunder are provided. The upper crushing rollers 3, 4 each have plural screw-like cutting blade groups whose torsion direction is reverse to each other in the axial direction, and coarse material fed with the rotation is collected between the opposite cutting blades to crush it, and also the lower crushing roller 10 is provided with plural screw-like cutting blades whose torsion direction is reverse to each other in the axial direction corresponding to the screw-like cutting blades of the upper cutting rollers 3, 4 and plural cutting crushing blades with inclined angles in the reverse direction to them and with rough pitch. To the cutting blade suitable places, main cutting blades 13 are attachably and detachably fitted.