Lift System Allows Precise Positioning of Huge Dragline
One of the world's largest precision lifting applications of land-based equipment has been successfully completed in Australia in order to replace a turntable bearing.
November 1, 2004 | By MRO Magazine
One of the world’s largest precision lifting applications of land-based equipment has been successfully completed in Australia in order to replace a turntable bearing.
G&S Engineering Services in Queensland used an Enerpac synchronous hydraulic lifting system to lift, within tolerances of 0.02 in., a huge mining dragline weighing more than 3,500 tons.
Draglines are probably the largest land-based equipment moving across the earth, typically ranging in size from 2,500 to 6,500 tons. For this repair job, the PLC-controlled hydraulic system used eighty 100-ton capacity hydraulic cylinders to lift the dragline at the Curragh coal mine in the Bowen Basin so that necessary maintenance could be done on the bearing surfaces on which it swivels.
The system also tilted the huge suspended weight to simulate different loads on the structure. The bearing surfaces could then be precisely machined to accommodate different loads and maximize the lifespan of the bearing surfaces.
The cylinders, controlled in groups of four around the perimeter of the dragline’s base, lifted it 0.4 in. at a time for optimum precision and control. They raised it a total of 8 in. to allow machining between the upper and lower rails on which a bearing is placed. The system simulated actual loading on the dragline to maximize and accurately predict the life of the bearing.
The high precision lifting job with the hydraulic system enabled exact aligning of bearings on the rail on which the dragline rotates.
The smaller and lighter cylinders translate into more space under and around the job, permitting G&S to employ uninterrupted use of the latest laser-guided machining systems when they were machining the upper rail on which the dragline rotates. The precision achieved by Enerpac’s synchronous system is so great that it can be used to safely tilt massive objects during lifting to enable exact aligning of upper and lower bearing surfaces.