1.It is safe and simple to operate 2.auto stop and anti-jamming function, auto-stop at end-point, auto wash 3. small compact this kind of jumbo is mainly used to drill blast holes for tunneling constructions in mining, metallurgy, water and electricity, railway, highway engineering, etc. This series use single booms to drill, with high efficiency and speed which can be 0.8-2 m/min. The advanced ...