Kelly Bushing In Oil & Gas Rigs Simple Guide
The Kelly drive bushing engages the master bushing in the rotary (either square drive or pin drive). As the rotary turns, the Kelly drive bushing turns with it to drive the Kelly. At the same time, as the Kelly works down, the rollers in the bushing allow the Kelly free movement and keep it centered in the rotary bore. In other words, it serves as a connection point between the rotary table and the drill string, enabling power transmission from the rotary table to the drill bit.
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