| 摘要 |
A double life shaft seal includes a seal case and an elastomeric sealing annulus having first and second seal lips adapted to be sequentially contacted by a rotating shaft. A tensioned garter spring is initially located on the sealing annulus so as to bias the first seal lip into operative sealing engagement with the shaft to provide a first service life, the spring being positioned thereat by spring biased expanded constriction ring restrained against axial movement by engagement with blocking lugs on the seal case. After predetermined wear of the first seal lip, the constriction ring contracts in diameter and loses contact with the blocking lugs at which time the ring and the garter spring are axially shifted to a second position wherein the garter spring is located so as to bias the second seal lip into operative sealing engagement with the shaft to provide a second service life.
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