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Turntable
A stationary heavy-duty rectangular steel case houses the rotating turntable.
The turntable is round in shape and is near the middle of the case. The turntable
produces a turning motion that machinery transfers to the pipe and bit. The case also
holds gears, bearings, and other components on which the turntable rotates. An
electric motor or gears and chains from the rig drawworks power the turntable.
Additional equipment transfers the turntable's turning motion to the drill pipe and
attached bit.
Master Bushing and Kelly Drive Bushing

A bushing is a fitting that goes inside an opening in a machine. A rotary table
master bushing fits inside the turntable. The turntable rotates the master bushing. The
master bushing has an opening through which crew members run pipe into the
wellbore.
A tapered bowl fits inside the master bushing. This bowl serves a vital function
when the pipe and bit are not rotating. When the driller stops the rotary table and uses
the rig's hoisting system to lift the pipe and bit off the bottom of the hole, it is often
necessary for crew members to suspend the pipe off bottom. To do so, they place a
set of segmented pipe gripping elements called "slips" around the pipe and into the
master bushing's tapered bowl. The slips firmly grip the pipe to keep it suspended off
the bottom.
The third piece of rotary equipment is the kelly drive bushing. A kelly drive
bushing transfers the master bushing's rotation to a special length of pipe called the
"kelly." The kelly drive bushing fits into the master bushing. Two types of master and
kelly drive bushing are available. One master bushing has four drive holes. Strong
steel pins on the bottom of a kelly drive bushing made for this type of master bushing
fit into the holes. When the master bushing rotates, the pins engaged in the drive
holes rotate the kelly drive bushing.

Kelly

The fourth major part of a rotary-table system is the kelly. A kelly is a special
length of pipe. It is not round like conventional pipe, however. Instead, it has four or
six flattened sides that run almost its entire length. Kellys are square or hexagonal in
cross section, instead of round, be-cause the flat sides enable the kelly to be rotated.
The kelly's flat sides mate with a corresponding square or hexagonal opening in the
kelly drive bushing. Therefore, when the driller inserts a square or hexagonal kelly
into the matching four- or six-sided opening in the kelly drive bushing and activates
the rotary table, the kelly drive bushing rotates the kelly. Moreover, because crew
members make up the drill string to the kelly, the kelly rotates the string and attached
bit.
The kelly slides easily into the drive-bushing opening. It is therefore free to
move up or down through the bushing opening, even as it rotates. The kelly's being
able to move through the rotating bushing is important because it allows the kelly to
follow the bit down as it drills deeper. When the driller stops rotating and lifts (picks

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