When using four slings, which two legs should determine the maximum angle?

The maximum angle for using four slings in a rigging application is determined by the diagonally opposite legs. This is because the force distribution in a rigging setup is influenced most by the angles formed between the lines of the slings and the load. When you have four slings secure a load, the two diagonally opposite slings will bear the primary responsibility for managing the angle, as they inherently balance the load between themselves while ensuring stability.

In this configuration, if the angle becomes too steep at the diagonally opposite legs, it can lead to increased stress and potential failure. Hence, it's essential to monitor the angles of the diagonal slings to ensure they are within safe operating limits, allowing for the most effective load distribution. This principle helps confirm the stability and safety of the rigging setup.