Picture two loads of the same mass: a welded steel frame and a finished painted component. They may impose a similar vertical load on the crane, but they present different problems for the sling. One has edges and awkward geometry; the other has a vulnerable finish and possible sling movement. A capacity tag alone cannot resolve that choice.
Capacity belongs to an arrangement
WLL means working load limit under specified conditions. Read the assembly marking with its instructions: number of legs, hitch, permitted angle and other restrictions. Straight lifting, basket and choke arrangements are not automatically equivalent.
In a symmetrical two-leg arrangement, tension increases as the legs incline further from vertical. An asymmetric load may also distribute the weight unequally. Simply adding individual leg capacities is therefore unreliable. Establish the mass, centre of gravity and attachment points before selecting the assembly.
Chain is more than its links
Chain, connectors, shortening devices and hooks must form a suitable assembly. A thicker chain need not have a greater capacity than a thinner chain of a different grade. Identification of the complete assembly matters more than an impression of strength.
Adjust leg length only with devices and methods intended for that purpose. A bolt through links or a knot is not a substitute for a shortening device. Inspection includes deformation, cracks, wear and fittings. Welding a damaged link in a workshop does not turn it into a verified lifting accessory; repair and return to use require their own controls.
Wire rope has an internal structure
A wire-rope sling conforms differently from chain, but its many wires and strands can be disrupted by a sharp bend or crushing. Broken wires, kinks, flattening, corrosion and damaged terminations are warning signs.
The contact radius where the rope bends over a load or fitting also matters. Assess suitability using the construction and documentation of the actual sling, rather than a universal ratio for every rope. A wire-rope sling is not automatically interchangeable with the hoist rope running on a crane drum.
Textile needs protection suited to the edge
Flat webbing slings and roundslings can suit vulnerable finishes. Sharp edges, local pressure, heat and chemicals can nevertheless make an apparently gentle contact unsafe. Polyester, polyamide and polypropylene do not have identical resistance to their surroundings.
An abrasion sleeve is not necessarily cut protection, a distinction specifically discussed in DGUV guidance for slingers. Protection must match the edge, load and movement. Turning a load changes the contact conditions. Sling colour cannot replace a legible identification label and instructions.
Check the entire connection
The hook, shackle, eye and lifting points also need assessment: capacity, permitted force direction and how the components bear against one another. Fitting inside a hook is not proof of correct seating. Tip loading or side loading cannot be treated as equivalent to the hook's intended loading.
For our illustrative painted component, textile might be a useful starting point, but an edge or a hot surface could change the decision. Chain might suit the frame, but without verified lifting points and a centre of gravity the lift is still not planned.
Information that makes selection possible
Record the mass and its source, dimensions, centre of gravity, contact-point photographs, temperature and chemical exposure. State whether the load will only be transported or also turned. Add the identification and documentation of available slings. Uncertainty is not resolved by trying a lift to see whether the equipment holds.
Separate damaged or unidentifiable accessories from usable stock for assessment. Specific rejection criteria and inspections depend on the type, instructions and applicable requirements. A sound overhead crane cannot compensate for an unsuitable connection between its hook and the load.
Overhead crane service and repairs
Sources and context
Selection and working procedures require the equipment documentation and a competent assessment of the conditions. HSE, OSHA and DGUV sources explain technical principles within their jurisdictions; they do not replace applicable local requirements or manufacturer instructions.