| 摘要 |
Male and female coupling members (120, 130) for a drill string (10) are provided. The male and female coupling members have abutment faces (122, 132), fitted with torque reducing rings (124, 135) of low-friction, material, and multi- start threads (140, 150), having higher lead angles .alpha. than conventional coupling threads, to enable uncoupling of the coupling members (120, 130) at reduced torque.
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