What effect does a choker hitch around a square load have on the Safe Working Load (SWL) for the sling?

A choker hitch reduces the Safe Working Load (SWL) or Working Load Limit (WLL) of a sling when used around a square load. This reduction occurs because the way the hitch is configured creates additional angles and stresses in the sling, which can weaken its capacity to carry the load safely.

In a choker hitch, the sling is looped around the load and then fed back through itself, creating a secure hold but also introducing a configuration that places more stress on the sling material. This added stress means that the effective lifting capacity is reduced compared to a straight-up lift with a vertical hitch. The general guideline in rigging is that using a choker hitch, especially on blocky or angular loads, leads to a decrease in the SWL/WLL, often cited as a reduction of about 50%.

Understanding this principle is crucial for ensuring safety during lifting operations. Proper rigging techniques and an awareness of how different hitches impact the SWL are vital components of safe lifting practices in excavator operation and other heavy lifting scenarios.