Abstract: A shredding system for reducing automobiles and other large pieces of metal scrap to fragments includes a feed chute for receiving the scrap and a shredder to which the chute directs scrap. A track feeder is located above the chute for both crushing the scrap and for controlling the speed at which it is introduced into the shredder. The vertical position of the track feeder is adjusted by a hydraulic system which enables the track feeder to float on the scrap and exert a predetermined yet variable force, to raise or lower under command, or to remain in a fixed position. The shredder has a cutter bar with four cutting edges so that when one is no longer effective the bar can be turned to place another cutting edge opposite the paths of the hammers in the shredder. Also, the cutter bar is adjustable toward and away from the hammer paths to maintain optimum spacing. In addition, the bar can be moved longitudinally so that grooves worn in it are moved out of alignment with the hammer paths.