| 摘要 |
A removable collar for an adjustable sub for use in the directional drilling of oil and gas wells is hinged at one side for ease of installation and removal and bolted at the other side. A set screw device within the collar body prevents loosening of the bolt when installed. A set screw bore extends obliquely from the main bore. A set screw is inserted completely into the set screw bore and the bolt is installed and tightened. The set screw is then partially retracted and frictionally and positively engages the bolt head to resist rotation thereof. A lock nut is alternatively retained in a slot to prevent retraction of the bolt.
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