Some lifting operations require that the lifting rings are offset from the load to be lifted, for example when the geometry of the part to be lifted prevents the shackle from moving properly. In this case, it is advisable to use a lifting ring with a spacer.
In general, the addition of a spacer reduces the working load limit of a lifting ring. But why? Here are some answers.
The importance of the lifting angle
CODIPRO’s lifting rings are designed to be used with a loading angle between 0° and 90°. Unless otherwise specified in the instruction manual, the same applies to lifting rings with spacer.
If the spacer is used with a 90° lifting angle, it is the least resistant. This is because the force applied induces a moment at the base of the spacer, which is taken up by a tension force in the bolt on the one hand, and a compression force in the spacer on the other.
All other things being equal, increasing the length of the spacer or increasing the applied force increases the stresses at the base of the assembly. Therefore, the greater the length of the spacer, the lower the WLL.
Resistance at 0°
The WLL of CODIPRO’s lifting rings are always given for a 90° lifting angle (lowest WLL). On request, the WLL can also be given for loads at 0°.
In case of a perfectly axial loading (0°±0), all the force passes through the bolt of the lifting ring. In this case, the spacer is more resistant. However, in practice, it is not common for the lifting angle to be exactly 0°. There is always – no matter how small – a radial component to the applied force.
It is therefore important to remember that the longer a spacer is, the greater this effect becomes, and the lower the WLL. It is therefore recommended to avoid lifting operations with a 90° angle in this case.
For any use of lifting rings with spacer, CODIPRO’s design office is at your disposal to design the part that best meets the specifications.