The so-called Load Safe system works using a clutch mechanism. Items such as overhead cranes, mobile cranes and offshore cranes can be fitted with the device, which measures the load and cuts off when it reaches dangerous levels.

Certex said items such as chain slings, webbing slings and shackles do not carry safe load indicators. “Chain blocks and lever hoists also have no such device fitted as standard,” it added.

When lifting with conventional blocks there is no safeguard incorporated in the design of equipment to prevent excessive overloading. Thus, judging when a load reaches its acceptable limit is often down to the skill and experience of individual operators.

"Unfortunately, this is where errors can occur," said Charles Gillespie, Certex sales and marketing director. "For instance," he continued, "it is all too common practice to extend the leverage by adding either a longer pipe to the lever hoist handle or using additional personnel to increase the manual effort on the hand chain when the lifting effort becomes too great."

Introduced four years ago, the Bulldog range includes chain blocks, lever hoists, girder trolleys and girder clamps.