Crawler portable drilling rig HC728: 1.hardness of the rock:f<8 2.work with air compressor 3,with diesel engine Crawler portable drilling rig HC728 :Features:1.Hydraulic motor with low rotation speed,large torque2.diesel engine,movement powerful and stable3.Equipped with auxiliary radiator,fit for cold,high location4.Adopt oil cylinder propulsion,make sure stable performance5. Multiple valve ...