Spotlight Rigging

By Seth Skydel Rigging Precision

“ There are well-known equations for determining the weight of a pick in crane operations,” said Zach Hayes, global product manager of sling chain and fittings at Kito Crosby.“ However, the static weight of the item being lifted is only part of the equation. Other forces, such as angular loads and horizontal forces, also impact rigging performance.”

To illustrate, Hayes offers a simple analogy: imagine carrying two five-gallon buckets of water. When held close to your body, they each feel as heavy as their actual weight. However, if you extend your arms outward, the strain increases because of added horizontal forces.

In rigging, this effect is significant. In a multi-point pick with two legs of chain, the horizontal force can dramatically alter the actual load on each sling. At a 90-degree angle, the force remains equal to the load weight. At 60 degrees, the force increases by approximately 15 %, and at 30 degrees, a sling leg could experience twice the vertical share of the load.

Accounting for these forces is crucial when choosing rigging products. One common point of failure, for example, are eye bolts, which are particularly vulnerable to angular loads.

“ An eye bolt rated for a vertical lift may lose up to 70 % of its capacity when used at a 45-degree angle,” Hayes explained.“ This can introduce a dangerous point of failure. In fact, eye bolts are one of the most frequent causes of lifting failures.”

Selecting the right rigging equipment can mitigate these risks.“ In non-repetitive lifting environments, chain is the most versatile option,” Hayes noted.“ When paired with an adjustable sling,

The GrabiQ all-inclusive chain sling system features adjustable chain slings, allowing for precise lifting of asymmetrical loads.

angles improve and even lifting of asymmetrical loads, such as L-shaped objects is ensured.”

Engineered Solutions

Kito Crosby offers a range of lifting and rigging products, including the Gunnebo Industries GrabiQ chain sling system. Designed for coupling, shortening and lifting, GrabiQ allows for precise control of asymmetrical loads by using one adjustable sling instead of separate long and short slings. The system also enables shortening chain lengths for low headroom applications and includes options for lifting bars, tubes and pipes.

Another key innovation is the midgrab chain shortener( MIG), which allows chain shortening at the hook rather than the master link. This is especially useful for long chain legs, as

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March 2025 • www. cranehotline. com