Rotary table (drilling rig)

The chains require constant oiling to prevent burning and seizing.

This is commonly used by crews in lieu of using a second pair of tongs to makeup or break out pipes.

These can generally be removed in two separate pieces to facilitate large items, e.g. drill bits, to pass through the rotary table.

The large gap in the center of the rotary bushings is referred to as the "bowl" due to its appearance.

Most recently manufactured rigs no longer feature rotary drives.

In this simple diagram of a drilling rig, #20 (in blue) is the rotary table. The kelly drive (#19) is inserted through the center of the rotary table and kelly bushings, and has free vertical (up & down) movement to allow downward force to be applied to the drill string , while the rotary table rotates it. (Note: Force is not actually applied from the top (as to push) but rather the weight is at the bottom of the drill string like a pendulum on a string.)