| 摘要 |
A pipe handling assembly in connection with an oil derrick comprises two pivotable and vertically movable arms having a grab head in the form of a U-shaped claw intended for transporting a stand of pipe, a drill collar or the like from the well center to a rack, and vice versa. The grab head on one arm, preferably the lower arm, is subdivided vertically into a lower U-shaped member fixedly connected to the arm via a housing and an upper U-shaped member rotatably relative to the lower member and provided with locking means for retaining the pipe, drill collar or the like. The two members are provided with rotation means intended to bring the upper, rotatable member from an arbitrary angular position into a locked position in which its claw aperture is in alignment with the claw aperture of the lower member. The rotation means which brings the two apertures into alignment, in a preferred embodiment, consists of the facing surfaces on the two members, which are formed as complementary, helical, inclined planes whose ends (entry and exit of the Helix) are connected via respective surfaces which form an acute angle relative to the centerline of the housing.
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