Drill blastholes for tunneling construction Explosion proof Twin boom Cross section: 5.2m x 4.5m Drilling speed 0.8-2m/m CMJ17 All hydraulic crawler drilling Jumbo is mainly used to drill blastholes for tunneling construction in mines of metallurgical, nonferrous metal, coal etc, and also hydro-power station, railroad, highway engineering, etc. The jumbo is designed with two drilling booms, ...