Seal for a rolling cone cutter earth boring bit

摘要

A seal acts as a barrier to the drilling fluid, pulverized cuttings and other materials in a borehole preventing the materials from entering the bearing area of a rolling cone cutter earth boring bit and retains lubricant inside the bearing area. A rolling cone cutter is rotatably mounted on a cantilevered bearing pin extending from the bit body. A "Z" seal is positioned between the cutter and bearing pin. An outer rigid seal ring is positioned around the bearing pin. The outer rigid seal ring is split to allow radial expansion and contraction. An inner rigid smaller diameter seal ring is positioned around the bearing pin. The inner rigid seal ring is also split to allow radial expansion and contraction. An elastomer ring is located between the inner and outer rigid rings and affixed to the rigid rings. Fluid in the borehole causes the elastomer ring to force the inner rigid ring to contract into tighter contact with the bearing pin and the lubricant between the bearing pin and the rolling cone cutter causes the elastomer ring to force the outer rigid ring to expand into tighter contact with said rolling cone cutter thereby preventing the ingress or egress of fluid and materials.