E21C27/00—Machines which completely free the mineral from the seam
E21C27/10—Machines which completely free the mineral from the seam by both slitting and breaking-down
E21C27/12—Machines which completely free the mineral from the seam by both slitting and breaking-down breaking-down effected by acting on the vertical face of the mineral, e.g. by percussive tools
E21C27/128—Machines which completely free the mineral from the seam by both slitting and breaking-down breaking-down effected by acting on the vertical face of the mineral, e.g. by percussive tools with breaking-down members functioning on the slitting level