| 摘要 |
A single-part hollow shear coupling is provided for connecting a downhole pu mp with the terminal member of a sucker rod string. The coupling is threadably connected to the sucker rod and the pump during normal operations, but can relatively easily be parted, if the pump becomes stuck, by pulling up on the still free sucker rod string. One end of the coupling has a pin incorporating an externally threaded head and the other end has an internally threaded cavity. A cylindrical, hollow body joining both ends is weakened by the groove, providing a stress concentratio n point, where the coupling will part, when exposed to predetermined desired load. The weakened part of the shear coupling is protected with a special coating, preventing corrosion and abrasion.
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