High Quality Content by WIKIPEDIA articles! Safe working load (SWL) is the load that a lifting device such as a crane, a cherry picker, or a lifting arrangement can safely lift, suspend or lower. Other synonyms include working load limit (WLL), which is the maximum working load designed by the manufacturer. The load represents a mass or force that is much less than that required to make the lifting equipment fail or yield. The SWL is calculated using a given safety factor (SF) which for lifting slings could be given for example 5:1. The failing load is also known as minimum breaking load (MBL).