Roll crusher

A comminuting machine, particularly a roll crusher, comprising a housing;

• two rotors mounted insaid housing for rotation about substantially horizontal axes and having axially staggered circumferentially extending annuli of external teeth, said rotors defining a nip and being arranged to rotate in opposite directions so that their teeth move from above toward, through and downwardly beyond said nip;
• a grate having two sets of several rows of teeth each, the rows of teeth of each of said sets alternating with said annuli of a different one of said rotors, said grate further having a frame including a pair of spaced-apart cheeks and crossbeams extending between and connecting said cheeks to one another, said crossbeams including a mediam crossbeam and two outer crossbeams, the rows of teeth of one of said sets being supported by said mediam crossbeam and one of said outer crossbeams, beams, and the rows of teeth of the other of said sets being supported by said median crossbeam and the other of said outer crossbeams;
• and mounting means provided on said housing and defining for said grate a pivot axis located at a level below one of said rotors, said grate being movable about said pivot axis between an operative position in which said rows of teeth extend at least from below between the neighboring annuli of teeth and an inoperative position in which said rows of teeth are located beneath and extend downwardly from said pivot axis, each of said rotors overlying said grate when the latter assumes said operative position and the annuli of teeth on said one rotor being staggered with reference to the annuli of teeth on the other of said rotors, as considered in the axial direction of said one rotor.