| 摘要 |
An oil or like fluid seal having a rigid exterior casing, a primary lip and an auxillary lip, with the primary or axially inner lip having a primary seal band surface which is generally cylindrical in its relaxed condition and which includes at least one hydrodynamic pumping element on its shaft contact surface, with the auxillary lip, in its relaxed condition, being of greater inside diameter than the primary lip, with the primary and secondary lips being spaced apart so as to define an intermediate annular groove of generally V-shaped cross-sections between them, with the pumping element acting to space portions of the primary lip apart from the associated shaft so as to provide initial venting of gas and vapors from the sealed cavity into the intermediate region and beneath the auxillary lip as cavity pressure increases so as avoid excessive pressure build up in the sealed region or sudden or erratic venting of such pressure.
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