Terex AC-500-2 All Terrain Crane
JPW Riggers, Inc. Syracuse, N.Y., recently acquired a Terex AC 500-2 all-terrain crane to assist with its wind turbine work at the Maple Ridge Wind Farm in Lowville, N.Y. The AC 500-2 served as an alternative to the lattice boom crawler cranes JPW typically uses for wind turbine construction and servicing.
With structural and operational components weighing tens of thousands of pounds, turbine erection and maintenance requires significant crane and rigging support. Heavy-duty crawler cranes are often used to handle the lift requirements of heavy loads and high winds. “These turbines are placed where the winds are prevalent as evidenced by locating Maple Ridge in the foothills of the Adirondacks,” says Dave Schwalm, executive vice president of JPW Riggers, Inc. of Syracuse, N.Y. “Small hydraulic cranes with high booms may offer the extension necessary to work on the turbine, but they only offer a 16 to 18 mph wind rating.”
JPW first used the AC 500-2 to lift a 35,000-pound generator 350 feet in the air for maintenance work on one of the wind turbines. “When hoisting a 35,000-pound generator 350 feet in the air, it’s nice to have a 22 mph wind rating for the crane,” said Schwalm. “Since we are often working in windy conditions, this extra capacity can mean the difference between putting the project on hold to wait for the wind to die down or installing the new generator and moving on to the next project.”
In the 600-ton capacity class and with a 478.3-foot maximum working height, the AC 500-2 offers various set-up configurations to handle lifting tasks. JPW’s crane can be moved in six to 16 loads, depending on job specifications. For the generator project, the company mobilized the crane in seven loads.
Empire Crane Co., Syracuse, N.Y., assisted with the crane rigging, using a 70-ton Terex RT 670 rough-terrain crane to stack the 11-ton counterweights on the AC 500-2. It also positioned the lattice work for assembly of the crane’s luffing jib. Workers had the crane rigged and ready for operation in one day.
The AC 500-2’s Sideways Superlift (SSL) system, which juts out to the sides at 30° or 60° angles to provide more structural stability, helps JPW when positioning gearboxes for wind turbine maintenance because it reduces bending of the main boom.
While offering high lift capacities, at just 56.1 feet long, the AC 500-2 offers a compact undercarriage. With eight axles (axles 1-4 and 6-8 steerable and axles 1, 2, 4, 5 driven), the crane efficiently moves onsite and can maneuver in confined spaces. In addition to enhancing crane stability, the star-type outrigger configuration saves space at the job site. A rated capacity limiter also protects crane operators from pushing the crane’s lifting potential beyond configured limits.
Within a half day, the AC 500-2 lifted and positioned the turbine’s new generator, quickly completing the 35,000-pound lift. Schwalm said that the crane was very smooth to operate, partially because of its IC-1 computer system controls, a computer system that delivers automated control over lifts to enhance operating safety. The operator inputs crane configuration parameters, load and radius via a touch screen. With all load charts stored in the IC-1, the system continuously monitors the lift, and green, yellow and red screen lights alert the operator when a load approaches lift configuration limits.
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