air /petrol /electric rock drill from china type:YT24,YT28,YN30,YN30A,YN30E,YN27,YN27C,YN27T certificate: ... . 4. In operation, it can be handled horizontally, vertically downward, or upward at an angle below 45°. When turned vertically downward ... for rock drilling. It can be converted into a breaker or a hammer for breaking, digging, splitting and ramming by changing ...