Selecting the connection method

Find out how connection methods affect lifting angles.

A working load for slings changes subject to the application. This is why doggers and riggers must know what they are lifting and how it will be attached to the load. Here are some examples:

The methods of lifting for synthetic slings 

The methods of lifting for alloy chain slings

If using multi-leg slings, the included angle is critical when selecting the correct sling for the job.

How many legs are lifting the load?

• Change in centre of gravity of load
• Variation in lengths of the slings
• Wire rope stretches (and can vary)
• Alloy chain pitch varies

All 2, 3 and 4 legged slings under the Australian Standards for lifting are based on 2 legs taking the majority of the load. The other legs only provide stability or balance. It is not always guaranteed that the weight of the load is evenly distributed. The sling leg lengths can vary through manufacturing.

Lifting angles

60 degrees is the preferred angle for safe lifting. This is because it is:

• the most efficient
• the easiest to work out (all sides are the same length)
• an angle that is very stable.

The chart below shows how you can calculate a safe angle for lifting by the use of a tape measure:

Calculating a safe maximum lifting angle

Why do angles affect loads?

All multi-leg slings exert a horizontal component of force. This increases as the included angle becomes greater.

No sling should be used if the included angle is more than 120 degrees. Beyond this point, the forces in the legs increase by a lot. This is shown below:

How angles affect loads

Note: do not use slings at angles within the diagram's shaded area. Angles of load less than 15 degrees should also be avoided. These can lead to the load becoming unstable.