Rig · Drilling
Top Drive
A motor that hangs from the traveling block and turns the drill string from the top, moving up and down the mast with it.
What it does
Rotates the string through a short pipe called the quill. It lets the crew drill with full stands and start pumping or rotating quickly while tripping, which reduces stuck pipe. The older alternative is a kelly turned by the rotary table on the rig floor.
Basics
| Drive | One or more electric or hydraulic motors |
| Connects through | Quill and saver sub |
| Alternative | Kelly and rotary table |
Common failures
- Worn saver sub damaging the drill pipe threads
Troubleshooting
- Symptom
- Thread damage on many connections
- Likely cause
- Worn saver sub
- What to check
- Inspect and replace the saver sub