| 摘要 |
In a downhole sucker rod string stress absorber, a relatively inelastic plunger of circular cross-section is mounted on a concentric shaft extending upwardly to an upper portion of the sucker rod string. A resiliently compressible cushion of circular cross-section is disposed below the plunger and above a lower portion of the sucker rod string. A disk may be seated between the cushion and the plunger to distribute forces more evenly on the surface of the cushion. A resiliently compressible cylindrical sleeve, preferably having a plurality of annular grooves spaced thereabout, surrounds the shaft above the plunger. A coupling, adapted for connection to the lower portion of the sucker rod string, has a threaded end with a compressive face which abuts the outer end of the compressible cushion. A guide slidably mounted on the shaft has a threaded end with a compressive face thereonwhich abuts the outer end of the compressible sleeve. A cylindrical housing connects the coupling and the guide with the compressible cushion, the compressible sleeve and the plunger therebetween, the length of the housing being such that the compressible cushion and sleeve are increasingly partially compressed between the compressive faces as the guide and/or coupling are threaded further into the housing.
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