... rock drill tool,composed of a small petrol engine,ann air compressor and a rock drill. ... is a portable machine,Its also can use with supporting stand.Drilling hole diameter 28mm-42mm, ... a Kind hand held drill built up with gasoline engine,Air pump,rock drill and the rotation ... 315*229 mmDiameter of engine pistonĪ58 mmStroke of engine piston70 mmRotating speed of engine with load>=2450 rpmDrilling speed ...