... Frictional and interlocking drilling rod are equipped with all kinds of slewing bucket and short or long optional helical bore ... and have drilling rod auto-assemble function.3.4Retractable ... , oil-burning, gas-burning, coal-burning), Stabilized SoilMixing Plants, Rotary Drilling Rigs... Rotary Drilling Rig (60m, 200m,300m,500m,1000m)