| 摘要 |
An earth boring bit having a lubrication system that includes a pressure compensator 19 and seals 29 to confine lubricant within the bearings between rotatable cutters and shafts, the seals being of the asymmetrical shear/compression type, each half of which having a load deflection curve resulting from components satisfying the following criteria: DH>ApS and DC>ApS [(S-1)/S]<1/2> Where: DH=Assembly deflection of shaft seal ring with bearing thrust faces in contact (in); DC=Assembly deflection of cutter seal ring with bearing thrust faces in contact (in); Ap=Axial cutter play (in); S=Ratio seal to cutter movement. Also preferably, DC SIMILAR DH[(S-1)/S]<1/2> The seal 29 comprises a pair of metal rings (45,47) having opposed sealing faces (49) with lubricant space (51) all within a seal groove, and a pair of resilient energizer rings (53,55) with annular surfaces opposing walls of groove and metal. rings. <IMAGE>
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