(57) A wrench assembly for making and breaking connections between tubular members, such
as a drill string and a top drive sub. The wrench assembly consists of a lower wrench
(33) and an upper wrench (31). The lower wrench (33) has a curved gate arm (41) and
a curved latch arm (43) pivotable between an open position and a closed position.
The gate arm (41) has a plurality of teeth on its outer surface, and the latch arm
(43) has a plurality of teeth on its inner surface, for locking engagement with the
teeth on the gate arm (41). The lower wrench (33) also has a clamping cylinder (61)
and a die block (59) for forcing the tubular member against the gate arm (41). The
upper wrench (31), mounted above the lower wrench (33), has a semicircular plate (65).
At least one spline (67) is mounted on the interior surface of the semicircular plate
(59) for engagement with at least one spline on the top drive sub. A fluid cylinder
(71) is provided for applying torque to the wrenches to rotate one of the wrenches
with respect to the other wrenches.
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