One of the world’s advanced heavy lifting systems was called into action recently, when Dawson Engineering in Townsville was commissioned to safely and precisely raise a 250-tonne nickel ore rail car tippler for maintenance.
The PLC-controlled Enerpac synchronous lifting system, supplied by Coates Hire Industrial Division, was used to ensure absolutely precise control of the four CLRG double-acting power lifting cylinders involved, so their plungers advanced at an identical rate within 0.5mm of each other.
The synchronous lifting system, the new versions of which can use 4-64 cylinders ranging from 10-1000 tonnes capacity each, is the same technology used to split a huge mining shovel in Queensland, and to hoist bridges and infrastructure components around the country.
Queensland Nickel Industries (QNI Yabulu) wished to ensure high levels of safety possible in the lift, so Dawson Engineering and Coates Hire specified a system that could achieve high objectives effortlessly.
Previously tipplers were lifted for bearing and wear surface servicing using four cylinders separately, often with one man per cylinder, co-ordinating his lift with the others by way of needle valving. Lift points would be monitored by measuring distance lifted, then adjusting the flow of oil to the leading and lagging cylinders.
The new system, PLC controlled totally by one operator through touch-screen simplicity, is capable of much higher precision and repeatability. The system can be expanded to up to 64 lift points and work down to tolerances of 0.1mm, which is incredible.
The tippler involved in the QNI lift was tipped by 20mm on one side, before being lifted from all four points specified by Dawsons Engineering using the Enerpac CLRG cylinders, which are high-tonnage models available in sizes from 50-1000 tons. The double-acting cylinders, which can provide both push and pull forces, feature built-in safety valves to prevent damage from accidental over-pressurisation, as well as a special bearing design that withstands sideload forces up to 10 per cent of the rated cylinder capacity without scoring.
Enerpac synchronous lifting equipment is designed for applications involving ultra precision civil, mechanical, industrial and maintenance engineering tasks.
The Premium, computer-controlled, synchronous hydraulic lifting system detailed in Enerpac’s new E325A catalogue uses digital synchronisation control, accurate to within a 0.1 millimetre between leading and lagging lifting points.
Synchronous lifting systems electronically control and monitor movement during the hydraulic raising, lowering, positioning or testing of heavy objects such as manufacturing machinery, motors, manufactured structures, buildings, bridges, oil platforms, ships, turbines, generators, mills, mining equipment and heavy, but delicate computerised/electrical equipment.
Operating through PLC control with touch-screen simplicity, the 700-bar system offers maximum stroke to finely balance complex, and sometimes delicate and potentially hazardous structures.
Synchronous lifting offers users’ with significant advantages over manual control, including safety, considerable time savings and virtually no internal stress in the object, helping to obviate potential problems arising later.
Simplicity is the key to the system. Specify the tolerance, specify the target, and start lifting. The user has to just monitor the lift, as the PLC controls everything else. Simplicity is the principle of this unique system. Every point of the load is automatically and synchronously moved and positioned, with accuracy to plus/minus 1mm in the basic version and 0.1mm in the premium version.
Useful integrated features including tilt and load sensing at each lift point, data logging and printout, as well as centre of gravity calculation.
The first versions of Enerpac’s synchronous lifting systems have already demonstrated their prodigious lifting ability on tasks, where safety and precision were at a premium, including splitting of a 3,500-tonne dragline at Curragh in Queensland for maintenance and lifting of bridges for repair.
Enerpac’s synchronous lifting systems have also been used in the construction of the world’s high bridge, the 343 metre high Millau Viaduct in France (which is twice as high as the Sydney Harbour Bridge), and the construction of North Sea oil rigs.