Importance

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Abstract

Apparatus for rotating a tubular well element about its longitudinal axis. There are first and second elongate casing sections pivotally connected to each other at a pivot. First and second driven sprockets are mounted, respectively, on the casing sections at locations remote from the pivot. A drive sprocket, mounted on the first casing section, is driven by a motor-gear assembly. A continuous chain is mounted around the drive sprocket, and around the first and second driven sprockets, having an inverse internal portion adapted to receive and directly contact the tubular well element to be rotated. Cylinders are connected between the casing sections to pivot them toward and away from each other and thus alternately clamp the inverse internal portion around the wall element, and release such element from the inverse internal portion. One end of each cylinder is pivotally connected to the first casing section at a point between the pivot and the first driven sprocket. The other end of each cylinder is pivotally connected to the second casing section at a point between the pivot and the second driven sprocket.

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First Claim