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