Hammer drill
（重定向自Hammerdrill）
A hammer drill, also known as a "rotary hammer", "roto-drill" or "hammering drill", (see also rotary drill) is a rotary drill with a hammering action. The hammering action provides a short, rapid hammer thrust to pulverize relatively brittle material and provide quicker drilling with less effort. These tools are usually electrically powered, and increasingly powered by batteries. The same technology is also used in electric "demolition hammers", also known as "chipping guns" or "breakers".