... rig on crawler base, max drilling capacity 40m, hole diameter 105 - 152mm, with diesel engine Main Technical Specifications Model No. DHK ... -140A Workable Rock F = 6 ~ 20 Hole Diameter 105 ~152mm Economic Drilling Depth 25m Working Air Pressure 1.0 ... DHK-140A for max drilling capacity 40 meter and hole 105 - 152mm