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.