Shackles must be greater or equal to the diameter of what?

• A. The Load Diameter
• B. The Rope Length
• C. The Pin Diameter
• D. The Rope Diameter

Answer: (D)

Shackles are sized by the opening through which the rope or sling passes. The interior bore of the shackle must be at least as large as the rope diameter to allow the rope to sit properly, move freely, and avoid being pinched or abraded against the sides. If the bore is smaller than the rope diameter, the rope won’t fit or will get distorted, creating severe stress concentrations and a potential failure under load. The other factors—rope length, pin diameter, or the load’s diameter—do not determine the necessary bore size for safe use in lifting; the key requirement is that the shackle diameter matches or exceeds the rope diameter.