SOME FACTS ABOUT LOAD CAPACITY

The load capacity of a single hook is dependent on many things, the most important are the material, wire diameter and orthogonal distance. An approximate formula true for a single hook:

Mmax ≈  σs x ø³/99,5e
Mmax = load where irreversible deformation starts (kg)
σs = bending strength ≈ 0,8 x Tensile strength (MPa)
e = distance (mm)

Typical dynamic behaviour of standard hooks when loaded is that maximum load, the load where the wire starts to be permanently deformed (yield stress) is the same for DV and R but approximately double for DV M. Then DV and DV M describe a “concave” load-extension line before the load falls or drops off, while R looks more like a convex figure.

Due to the shape of the hook the load capacity after exceeding the irreversible deformation limit and safety margin are very different. R hooks have a low margin and DV much higher. DV/DVM shape is therefore a safer choice.