... 3)used to drill low compressive strength API 8 1/2" Kingdream Newest IADC 437 TCI tricone bit1 ... 6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8",9 7/8",12 1/4",17 1/2", ... well drillingMain structure features: 1. High precision journal bearing with two thrust faces. Head bearing surface is hardfaced. ... highly elastic rubber energizers are seated separately in head and cone sealing areas functioning as static seals. ...