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Troubleshooting GuideRope Spooling Unevenly on the Drum
Uneven spooling brings the rope to its discard criterion early.
Why it matters
Drum grooves are cut so the rope sits in exactly the same place on every wrap. Once the rope loses this pattern, the wraps overlap; the upper wrap crushes the one below it.
Crushing flattens the individual wires and disrupts the rope's internal structure. A rope that still looks sound from the outside has reduced load capacity and reaches its discard criterion early.
Possible causes
| Possible cause | How to identify it |
|---|---|
| Fleet angle out of limit | Rope enters the groove at an angle, jumping at the edge |
| Drum groove worn | Groove profile has rounded off, depth reduced |
| Rope twisted | Rope rotates on its own axis, hook spins freely |
| Hook block rotating | Hook rotates under load, rope takes on a spiral |
| Rope fitted incorrectly | Lay direction reversed, wrong from the very first wrap |
| Sheave bearing seized | Sheave does not rotate freely, rope is dragged |
Step-by-step diagnosis
- Watch the spoolingSlowly lower and raise the hook to see where it goes wrong.
- Check the fleet angleInspect the rope's entry angle into the groove at the extreme positions.
- Measure the drum grooveIs the groove profile and depth worn.
- Check for rope torsionRelease the hook unloaded and watch whether it rotates.
- Check the hook blockIs the bearing free, does the anti-rotation device work.
- Check the sheavesDoes every sheave rotate freely, are the housings worn.
- Inspect the ropeIf crushing or flattening is present, assess it against the discard criterion.
Fix and prevention
A fleet angle problem is fixed by checking the axial position of the sheaves and drum; this measurement must be verified after installation.
If the drum groove is worn, the drum is re-machined or replaced. Fitting a new rope onto a worn groove wears out the new rope quickly too.
Rope torsion is relieved by letting the rope hang free so the twist can release. If the hook block rotates, check the bearing and the anti-rotation device. When replacing the rope, the fitting direction and lay direction must always be verified.
Technical terms
| Term | What it means |
|---|---|
| Fleet angle | The angle at which the rope enters the drum groove; past its limit, spooling breaks down. |
| Drum groove | The helical groove cut into the drum for the rope to sit in. |
| Hook block | The block carrying the hook and lower sheaves. |
| Anti-rotation device | A mechanism that limits the hook rotating under load. |
Frequently asked questions
Can I spool the rope in the reverse direction?
No. The spooling direction must match the rope's lay direction; reversing it produces torsion and uneven spooling.
The spooling looks bad but the rope looks sound — can it wait?
If crushing has started, the rope's internal structure degrades faster than it appears. Continuing without fixing the spooling means a rope replacement soon.