... WDH-500 is centrally driven by a Cummins diesel engine, with all the mechanism/systems of traveling, rotating, driving, feeding, rod ... Air Circulation drilling, DTH Reverse Air Circulation drilling. If work with rotary drill bit, it can be used also for mud ... Rod : 3M/PCDia. of Drilling Rod : Dia.89/Dia.108MMAir R/C Drilling Rod Dia. : Dia. 108MM, 89MMApplicable Condition : Soil, Weathered Rock ...