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What is a Safe Working Load (SWL)?

safe working load (SWL) photo

A safe working load is an important safety measure to checkmate the lifting equipment’s overloading capacity. 

According to Wikipedia, a safe working load (SWL)is the maximum force a piece of lifting equipment, lifting device or accessory can exert, lift, suspend or lower a given mass without fear of breaking. 

Lifting equipment.

Lifting equipment is the 

  • Cranes 
  • Forklift trucks
  • Hoists
  • Manually operated chain blocks pull lifts, 
  • Mobile elevating platforms

And some other smaller accessories such as 

  • Ropes.
  • Chains.
  • Slings.
  • Eyebolts.
  • Shackles.
  • Personal safety harness.
  • Attachments used for connecting Load to the lifting device.

The safe working load (SWL) can be called the Normal Working Load (NWL)-All lifting equipment must have an SWL. 

In simpler terms, when you have a lifting belt to carry a load from point A to point B. The Lifting belt should be able to lift the load safely without breaking during the process. Any lifting equipment that carries a piece of load beyond its safe working load, there is a probability that the equipment will sustain damage in the activity. 

How to calculate the safe working load of an equipment

An SWL is the lifting equipment’s minimum breaking strength divided by the safety factor that is constant or assigned to a particular type of equipment.


MBL is the Minimum breaking load

SF is the safety factor between 4 to 6 but can increase to 10 if the equipment poses a greater risk. The two acronyms, MBL and MBS are the same. 

MBS is the minimum breaking strength. 

For example, a chain with an MBL of 2000 Lbf with a safety factor of 5 will have an SWL of 400 Lbf. 

Difference between Safe Working Load (SWL) and Working Load Limit ( WLL).

Safe working load is now an older term of Working load limit (WLL)

WLL replaced SWL because the SWL definition is not specific, leading to legal implications. The SWL was replaced with WLL, firstly in the USA standards, then EU and ISO standards. 

WLL is defined as the maximum mass or force that a product is authorized to support in general service when the pull is applied in line unless noted otherwise concerning the centre line of the product. 

Also, WLL can be defined as the maximum load an item can lift in a particular configuration or location. It is calculated the same way as the SWL. 

Who sets the capacity of lifting equipment?

The manufacturer of lifting equipment sets the lifting capacity and equally recommends the maximum load capacity of the lifting equipment. 

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