... with simple structure and reliable performance. Adopting constant WOB auto-bit-feed device, a patent of Honghua , the WOB is ... is independent and lifted hydraulically (ZJ70DBS), without contacting the drill floor, with little vibration, and convenient for installation and ... )1350(135)1700(170)2250(225)3150(315)4500(450)Drill line number810101212Dia. of wireline, mm2929323538Max. pull of fastline, ...