Abstract: A cutting machine for cutting ligneous materials into small pieces comprises a toothed cutting cylinder and a reaction member. In a mobile version of the machine the reaction member is in the form of a toothed felling cylinder 14, which is tangentially mounted with the cutting cylinder within a frame. The cutting and felling cylinders are coupled to a mechanism for driving them in rotation in such manner that their angular speeds are equal. The number of cutter blades carries by the cutting cylinder is equal to, or an integral multiple of, the number of teeth on the felling cylinder. The frame is mounted on a vehicle chassis so as to be rotatable relative thereto about two axes at right angles to each other. Jacks are provided for orientating the frame relative to the chassis which itself is tiltable by jacks with respect to a driving undercarriage.