along a sloping curve c where the outer rolls 100 u2032 100 u2033 respectively and the inner rolls 101 102 respectively are at different horizontal heights with respect to the frame 110 see fig1 a the outer rolls are placed higher than the inner rolls and the intermediate rolls between them are on heights which are progressively lower going from the outer rolls towards the inner rolls both the inner rolls are at substantially the same height and both inner rolls are at substantially the same height in this way the material to be shredded will tend to fall towards the middle of the roll arrangement as opposed to staying at the extreme ends of the roll arrangement this enhances the shredding capacity by avoiding still standing or stuck material at the walls of the shredder because of the periodic reversal of the roll rotating directions material will not gather along the sides of the shredder where the rolls are held to the frame preferably a pressure sensing means 501 see fig5 a is connected to the drive system to automatically reverse the roll rotation directions in case material gets stuck in the roll arrangement detection of high pressure or slow down of rotation speed of the rolls also a timer arrangement 502 see fig2 c will periodically reverse the roll rotation direction as described fig1 a to 12 c show a sequence where a roll off type truck 900 u2032 is used to load a shredding apparatus.