... drilling rig 3,CE,ISO9001 4,Warranty 2Ys 2012 New type DTH drilling rig:Zhengzhou Dayu Machinery Co.,Ltd. ... equipment have small vibration and working stable. 3,New type boom of Dayu DTH drilling rigThe scope adjustable sysytem ... and rotating system of Dayu DTH drilling rigNew type swing mechanism constituted by cycloidal hydraulic motor and ... Dayu Machinery Co.,Ltd web: 2012 New type DTH drilling rig