1.3.20 Working Load Limit (WLL)

The working load limit is the maximum load (mass) that an item of lifting equipment is designed to raise, lower or suspend. In some standards and documents WLL is referred to as ‘maximum SWL.’ This term is more generally used for lifting accessories, but lifting appliances are now commonly marked with a rated capacity, see section 1.3.13 Rated Capacity

Note

  1. Much confusion exists between the terms ‘SWL’, ‘working load limit’ and ‘rated capacity’. By way of explanation, working load limit or rated capacity is the load value assigned to the ‘maximum’ SWL under ideal conditions (by calculation) and in most cases the working load limit or rated capacity and the SWL will be the same. However, depending upon the conditions of use, it may be necessary for the Competent Person to reduce this to a lower SWL and it is in these cases that the working load limit or rated capacity and SWL will differ.

  2. If the risk assessment of the application indicate that such reduction may be required, it is essential that the user declares this information at the time of ordering so that the correct SWL may be attributed to the equipment and documentation. In the absence of such a declaration, the manufacturer or supplier will assume that the application is suitable for equipment rated with the SWL equal to the working load limit. If the equipment is in service or the user has not declared this information to the manufacturer, then it is the user’s responsibility to determine and mark the appropriate SWL.

  3. The conditions where it may be necessary to reduce the working load limit to a lower SWL are HAZARDOUS DUTIES. Hazardous duties could, for example, be environmental conditions such as extremes of temperature, high windspeeds or lifting procedures such as a likelihood of shock loading or inaccuracy of weight. When such circumstances arise, it is essential that systems should be instituted to prevent normally rated equipment being used to its full capacity.

  4. Whilst it is the responsibility of the user to take such steps, the following advice should be considered:

    1. For specific installations where the equipment is fixed permanently in position, the equipment may be marked with the reduced SWL for that specific duty.

    2. For specific installations where the equipment is portable, the user should provide written instructions to the operative which include an instruction to use a normally rated piece of equipment (i.e. SWL = WLL) but of appropriately higher capacity thus achieving the same effective reduction.

    3. For an industry or a definable section of an industry where the majority of tasks require equipment having a reduced working load, then all the equipment should have a reduced working load i.e. that corresponding to the most hazardous duty.