... . 2, drive kelly spinner by matching with master bushing Roller kelly bushingRoller kelly bushing is a necessary tool for drilling. It is ... to drive kelly spinner by matching with master bushing. Through rotating of four rollers, the friction between rollers and ... *28.318*18*27.520*20*27.5WeightKg700730670420460340400lb1540161014709241012750808 Roller kelly bushing