... 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 ... ,537,547,617,637,737IADC CODE116,117,126,127,136,137,216,217,316,317,346,347RPM(r/min)140~60WOB ... bearing with two thrust faces. Ball lock the cone. Hardfaced head bearing surface. Cone bearing inlaid with friction-reducing alloy and then ...