Device for Hammer Drill Small 320×142 Medium 640×283 Large 1024×453 Download Tiff Original 2400×1062 | (560.8 KB) Description This is a hammer drill, also known as a rotary hammer, a pneumatically powered mechanism which uses percussion to penetrate rock. Keywords device, drill, Hammer, hammerdrill, percussion, pneumatics, tool Galleries Power Tools Source: Government Printing Office Official Gazette (Washingon, DC: Government Printing Office, 1912) Courtesy the private collection of Roy Winkelman
