Wire Rope & Lifting — validation & limitations

What it calculates

• ISO 2408 / EN 12385-4 rope selection by duty class (M3–M8): required MBL, minimum diameter and selected standard diameter from the breaking-force formula F_min = K·d²·Rr/1000
• FEM 1.001 reeving efficiency: drum pull force and system mechanical efficiency for 1–12 falls using the geometric tension-distribution formula (not the over-conservative η_s^n approximation)
• FEM 1.001 load combinations LC1–LC3: dynamic factor φ₂, wind load, inertia and skew forces against the allowable rope load
• D/d bending-fatigue check: minimum sheave/drum diameter as the stricter of the duty-class ratio and the rope-construction minimum (tool values), and a fatigue-life sensitivity chart as a function of D/d ratio
• Bending-cycle life estimate (an engineering form, not from FEM 1.001, with an estimated rope-tension factor — rough and conservative): estimated operating hours to rope replacement at 50% of N_f for the given construction and cycles per hour
• Elastic and constructional elongation: Hooke's law on metallic area plus construction bedding-in, critical for hoist-height accuracy
• Multi-construction rope comparison: 6×19 FC, 6×37 FC, 6×19 IWRC and 8×19 ranked by mass and achieved safety factor for the given duty, with environmental and cyclic derating applied

Standards this tool applies

• ISO 2408 — Rope selection by duty-class safety factor Zp (ISO 4308-1 / FEM 1.001) using the ISO 2408 / EN 12385-4 K factor for MBL — minimum diameter (8–40 mm range), safety factor, reeving efficiency, fatigue-life estimate and multi-construction comparison. D/d minima are tool values.

Validation evidence — independent reference cases (1)

Each case runs the tool's engine on a worked example whose values come from a published source or a hand derivation from the cited equations, and an automated regression test asserts the engine against those values within the stated tolerance. "Conservative" means the engine is known to sit on the safe side of the reference and the test asserts that side. Sources are cited; their text is not reproduced.

• Rope diameter selection and rope SF against duty-class Zp

  Agrees

  Source: ISO 4308-1:2003 (superseded by ISO 16625:2013, same Zp) §5 (d_min = c·sqrt(S)); EN 12385-4:2002 minimum breaking force; FEM 1.001 reeving efficiency

  Inputs: W 80 kN, 2 falls, phi 1.1, M6 (Zp 5.6), 6x19 IWRC K 0.356, grade 1960

  Quantity	Reference value	Tolerance
  lead-line tension S (kN)	44.44444	1e-6 relative
  d_min (mm)	18.8864	1e-6 relative
  selected diameter (mm)	20	exact
  SF at 20 mm	6.27984	1e-6 relative

  tests/golden/REF-wirerope-rope-sf-iso4308.golden.test.ts

Limitations

Not checked by this tool

• End terminations and fitting efficiency (sockets, ferrules, clips) — MBL is the rope's; derate for the termination per EN 13411 or the maker
• Drum shell strength under multi-layer rope pressure — Not checked; design the drum shell for the wound-on rope pressure with the crane code or the drum maker
• Sheave and drum groove profile (groove radius, depth) — Specify the groove geometry per ISO 16625 or the rope maker
• Deflection or lead sheaves between the block and the drum — Not modelled; each adds a sheave loss — lower the sheave efficiency to include them
• Rope torque and block spin on high single-fall lifts — Not checked; choose a rotation-resistant construction with the rope maker
• Man-riding and special-duty safety factors — Higher factors than this tool applies are required; apply the governing rules