| 摘要 |
The assembly is designed to convert a conventional land rig to "top drive". It comprises a torque track that is shipped in sections and is assembled to form a rigid track extending vertically in the derrick.á The track is rigidly attached to the derrick only at its base, so that the track is free to twist and deflect laterally along its length. The housing of the top drive is connected by an angled, pivotally mounted link means with a tubular bushing that embraces and slides along the track. The link means and bushing are adapted to restrain rotation of the housing relative to the track, while transmitting both side and torque reactive loads to the track. áThe angled pivoting link enables the top drive to be displaced outwardly to a position over the mousehole. The top drive incorporates a hydraulic motor and gear drive assembly for rotating a drive shaft connecting the drill string and hoisting means. The housing does not carry the drill string load and can be made lighter and more c ompact as a result.
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