... .9mm), 9 1/2"(241mm),9 5/8"(245mm), 11 5/8"(295mm),12 1/4"(311mm), 13 5/8"(346mm),14 3/4"(374mm), 15 ... HA(rubber sealed journal bearing)Aircooled bearing typeApplicable FormationsSoft formations with low compressive strength and high drillability, such as mudstone, ... the cone. Hardfaced head bearing surface. Cone bearing inlaid with friction-reducing alloy and then silver-plated. Abrasion resistance and ...