... and drilling to have high-speed-bored hole; if deployed with air-compressor and pneumatic in-the-hole hammer, and accepted ... followed drill tools, the drilling rig can drill the hole with cannula together in those unstable stratum such as conglomerate stratum ... construction site, more suitable for constructing on the falsework.2) With dual-hydraulicmotor, it has high torque, low gravity center, and good ...