DIFF Subgroup
E21C 27/28 by percussive drills with breaking-down means, e.g. wedge-shaped tools
Introduced: September 1968
Full Title
Machines which completely free the mineral from the seam > Mineral freed by means not involving slitting > by percussive drills with breaking-down means, e.g. wedge-shaped tools
No child classifications to compare. This is a leaf node in both IPC and CPC.