Depending on the intended usage, hoists are rated in duty rating groups according to ISO 4301-1. The duty rating group indicades the permissible working time and permissible utilization of the hoist equipment at full or partial load. Depending on the duty rating group, the safety factor of the chain (ratio of working and breaking load) is determined.
Duty rating groups according to ISO 4301-1
M1 .... Manual hoist
M2, M3, M4, M5 ..... Motor driven hoist