| 摘要 |
A shock absorber from an oil well drill string mounted therein adjacent its drill bit to cushion drill bit impacts in hard formations and having an elongate tubular mandrel, for connection with said bit, slidably mounted in and drivingly connected to an elongate tubular housing coupled in the drill string. Tubular housing is composed of upper, intermediate and lower tubular sections, preferably; the uppermost has a bore complementary to and slidably engaged by upper packing means on upper end of mandrel, intermediate section has a bore complementary to and in slidable engagement with the mandrel and the lowermost has an upper bore complementary to and slidably engaged by downwardly biased lower packing means slidably confined upon mandrel and a lower bore complementary to mandrel with slidable drive connection between mandrel and housing therein. Upper and lower packing means coact to provide upper annular sealed chamber therebetween composed of bores of housing sections and containing noncompressible fluid to cushion drill bit impacts; sealing means, at the bottom of bore of lowermost housing section and in slidable engagement with mandrel, coacts with lower packing means to form lower annular chamber enclosing slidable drive connection and containing lubricant therefor; flow control means in lower portion of upper chamber to resist relative upward reciprocation of mandrel.
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