... bearing are improved and suitable for high rotary speed.4.Seal and Lubrication of this series tricone rock bit ... applications.6.Main AvailabilitySize Bit TypeIn.mm6152.4 4.7,517, 537, 617, 637 6 1/2 165.1437,517,537,617, ... 1/2215.9437, 535,517, 537,617,6379 1/2241.3437, 517,537,617,6379 5/8244.5517,535,5379 7/ ... 8250.8517,53712 1/4311.1437, 517,535, 537,617,63717 1/2444.5517,535,537 ...