... 3,CE,ISO9001 4,Warranty 2Ys 2012 New type DTH drilling rig:Zhengzhou Dayu Machinery Co.,Ltd. ... have small vibration and working stable. 3,New type boom of Dayu DTH drilling rigThe scope adjustable ... hole scope larger and also can drill low level hole 4,Powerful feeding and rotating system of ... Dayu DTH drilling rigNew type swing mechanism constituted by cycloidal hydraulic motor and ...