| 摘要 |
A tubing tightener which is readily adaptable to either clockwise or anti-clockw ise rotational setting operation and which uses a series of drag slips having integr al drag and slip surface regions. The drag surface regions are substantially smooth and are advan ced into contact with a wellbore with the slip surface regions retracted, when the tighte ner is in its unlocked orientation. The slip surface regions are serrated to provide a positiv e engagement with the wellbore and are advanced into engagement with the wellbore with the dr ag surface regions retracted, when the tightener is in its locked orientation. The drag sli ps are caused to rock about a point of contact between the drag slip surfaces and the wellbore , located intermediate the drag and slip surface regions, in order to advance the appropri ate surface region of each drag slip into engagement with the wellbore. The invention provid es for a compact, lightweight construction with improved reliability and increased bypass around the tightener.
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