Wire Rope Calculator

Select rope diameter and grade based on FEM/ISO duty classes.

1. Load Parameters

Ton

kg

Typ: 1.1 - 1.3

2. Reeving & Duty Class

%

Auto-filled

3. Hardware Dimensions

mm

mm

Calculation Result

ROPE SELECTION

Max Rope Tension: 0.0 kN
Req. Safety Factor: 4.0
0 kN
Min Diameter: 0.0 mm
Select Size: --
Drum D/d Ratio Check
Sheave D/d Ratio Check

FEM 1.001 Duty Class Standards

Duty Class Safety Factor (Zp) Min Drum Ratio (D/d) Min Sheave Ratio (D/d)
M1 - M3 3.0 - 3.5 14.0 16.0
M4 4.0 16.0 18.0
M5 4.5 18.0 20.0
M6 5.0 20.0 22.4
M7 - M8 6.3 - 9.0 22.4 25.0

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Understanding Wire Rope Sizing

The wire rope is the literal "lifeline" of an EOT crane. Selecting the correct rope diameter and construction is vital for load-carrying capacity, fatigue life, and overall safety. This calculator follows the guidelines of ISO 4308 and FEM 1.001 standards.

Key Design Factors

  • Total Vertical Load: The sum of the Safe Working Load (SWL), hook block weight, and the weight of the rope itself (for very high lifts).
  • Number of Falls: Distributing the load across multiple falls (e.g., 4 falls) reduces the tension in a single part of the rope, allowing for a smaller diameter rope to be used.
  • Safety Factor (Zp): FEM standards require a minimum safety factor (typically ranging from 3.55 to 9.0 based on duty class M1-M8) between the rope's Minimum Breaking Force (MBF) and the maximum static tension.
  • Selection Factor (C): A constant derived from the duty class and safety requirements, used to calculate the minimum required rope diameter directly using the formula: d_min = C × √S where S is the rope tension.

Rope Construction & MBF

  • Minimum Breaking Force (MBF): The load at which the rope is guaranteed to fail. Your selected rope MUST have an MBF greater than (Max Tension × Required Safety Factor).
  • Construction (6x36, 8x19, 19x7): Affects the flexibility, fill factor, and resistance to rotation. Standard 6-strand ropes are used for general hoisting, while rotation-resistant ropes are needed for high-lift single-fall applications.

Results Explained

  • Calculated Min. Diameter: The absolute smallest rope size that meets the safety factor requirements for your specific duty class.
  • Static Safety Factor: The actual factor of safety provided by your specific combination of rope diameter, grade, and configuration.

Inspection and Replacement Guides

After sizing the rope, use the inspection cluster to control real-life replacement risk. Sizing alone does not cover broken wires, diameter reduction, corrosion, NDT findings, or discard criteria.

Wire Rope Inspection Guide Broken Wires in Wire Rope Diameter Tolerance Replacement Period