The performance of all wire ropes is depended on the good condition and sufficient dimensions of sheaves and drums. Too small sheaves and drums will reduce the service life of a rope. This is more a question of ‘performance’ rather than ‘safety’. The following table is based upon recommendations by the Wire Rope Technical Board:

Sheave opening angle should be 35° to 45° for applications with fleet angles ≤ 1.5°, for larger fleet angles use 60° opening.

Maximum rope fleet angle for general purpose ropes should not exceed 4°, for non-rotating/rotation resistant types and Python® Power 9 and Ultra the fleet angle should not exceed 1.5°.

 
CONSTRUCTION Suggested
D/d ratio
19×7 / 18×7 34
6×26 WS 30
6×25 Filler, 6×31 WS, Compac® 626 26
Python® Power 9, Ultra 26
6×36 WS, Construct 6, Compac® 636 23
8×25, Python® Super 8 (all types), Multi 20
Compac® 18 & 35 and Hoist 20
8×36 WS 18

Recommended Sheave and Drum Contours:
Groove radii minimum:
0.53 to 0.535x d for new rope
Groove radii maximum:
0.55 to 0.56x d
Sheave Groove depth:
1.5 x d
Drum Pitch for SINGLE layer minimum:
2.065 x groove radii
Drum Pitch for SINGLE layer maximum:
2.18 x groove radii
Drum groove depth:
minimum ≥ 0.375x d for helical grooved

Hardness: As wire rope has a hardness of about 50-55RC we recommend that the hardness of sheaves and drums is at least 35 RC, better is 40-45 RC.

 

Multi-layer drum systems should use Hi-Pac™ or ForcePac™ compacted Python® rope constructions having a steel core. The higher fill factor of such rope constructions will offer a greater resistance to crushing and flattening than conventional rope types. This is particularly important for boom hoist ropes on lattice boom cranes at the cross over point from one rope winding to the next.

Cranes equipped with multi-layer drum systems which require rotation-resistant or non-rotating rope are best served with Python® or Python Compac® rope constructions (Python® Compac 18 and 35) as these have a smooth outer surface allowing the rope to better ‘glide’ from one winding into the next. To further reduce drum crushing have the rope layers wound onto the drum with about 5-10% of the WLL and avoid that the first layer unspools and re-spools without tension. This would cause a ‘soft’ bottom layer which will flatten rather quickly.

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HiPacᵀᴹ and particularly ForcePacᵀᴹ compacted Python® ropes also help reduce strand interlocking which normally occurs at adjacent rope wraps. This is caused by too large of fleet angles as well as is the cause of multiple layer windings on smooth (ungrooved) drums.

Compac® and Python® ropes have a smooth and very round outer rope surface which helps to minimize abrasive wear due to strand-to-strand contacts.

For further information please refer to our page “Use and Care of Wire Rope”

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