The jib cranes, which each had a working load limit of 1.5t, were used to provide a second point of evacuation from a series of shafts, in case of an emergency in which workers needed to be stretchered out.
The cranes were supplied by Ranger Lifting and provided 6.5m underslung height with 6m reach, and heights of lift ranging from 26m to 70m. They were paired with 3t-capacity electric chain hoists from Swiss manufacturer GIS, which were downgraded to 1.5t to facilitate man riding. The original specifications of the jib cranes covered use for both man riding and general lifting. It was later decided, however, to restrict their use to personnel lifting, primarily because of duty cycle issues based on the significant height of the lift.
All of the cranes were also fitted with Straightpoint load cells with read-out, as well as pendant and remote controls and overload protection.
Ashley Thacker, general manager at Ranger Lifting, said: “Strict standardisation covers the use of cranes for personnel lifting, meaning a user-friendly, accurate, reliable load measuring solution was required. The large scoreboard displays manufactured by SP ticked those boxes and, if required in an emergency situation, clearly communicate the weight being lifted so the end user could be sure to be operating in line with relevant standards.
“Given the high profile of the site we only sourced from the best manufacturers in each component area. We only worked with suppliers who not only excel in manufacturing, but support that with professional paperwork, top quality engineering drawings, and flexibility to work within the most stringent project-specific requirements.”
David Ayling, director at Straightpoint, said: “It was clear that Ranger had a need to ensure their client conformed to local standards even if the need arose to employ the jib cranes in an emergency situation. Presenting data clearly in real time would have given them great peace of mind. The cabled load shackle was well suited to the demands of this application.”
Upon installation, Ranger used the load shackles to conduct load testing with water bags.
