... rig WDH-500 is centrally driven by a Cummins diesel engine, with all the mechanism/systems of traveling, rotating, driving, feeding, rod ... /driven. This allows the drilling rig works with high efficiency, ease and conveniences. With the support of Medium or High Pressure Air ... be used for DTH Air Circulation drilling, DTH Reverse Air Circulation drilling. If work with rotary drill bit, it can be used ...