a material reducing apparatus comprising a feed conveyor , for conveying material to be reduced , and a feed roller cooperating with the feed conveyor . an upwardly rotatable rotor carrying a plurality of strikers which facilitate reduction of the material to be reduced and an anvil cooperating with the plurality of strikers to facilitate further reduction of the material to be reduced . a grate assembly , located adjacent an arcuate path of the rotor , which permits sufficiently reduced material to pass therethrough . the material reducing apparatus further includes a failsafe system which comprising an accelerometer supported by the rotor and coupled to a control system such that the accelerometer , upon detection of the rotor contacting a hard material , sends a signal to the control system . if the signal indicates a sufficiently large material , the control system reverses a rotational direction of the feed roller so that the feed roll rotates to withdraw the hard material from contact with the rotor . a section of the grate assembly may also be moved away from the rotor , by a release device , upon the release device receiving a command from the control system .