Rig · Drilling
Crown & Traveling Block
Two sets of pulleys: the crown block fixed at the top of the mast and the traveling block that moves up and down below it, joined by the drilling line.
What it does
Together they multiply mechanical advantage, so a fairly thin wire rope can lift and lower drill strings, casing and liners much heavier than the rope alone could hold.
Basics
| Crown block | Fixed pulleys at the top of the mast |
| Traveling block | Moving pulleys inside the mast |
| Line care | Slip and cut to avoid fatigue |
Common failures
- Fatigue failure of the drilling line
Troubleshooting
- Symptom
- Line has done its planned work
- Likely cause
- Accumulated fatigue
- What to check
- Slip fresh line through the blocks and cut off the worn section