... 1/2"(165mm), 6 5/8"(168mm),7 1/2"(190mm), 7 7/8"(200mm),8 1/2"(215.9mm), 9 1/2"(241mm),9 5/8"(245mm), 11 5/8"(295mm),12 1 ... rubber sealed journal bearing)Aircooled bearing typeApplicable FormationsSoft formations with low compressive strength and high drillability, such as ... by matching cutting structure with different tooth shape, tooth density and tooth exposure height. 17 1/2" milled tooth tricone ...