ALL TERRAIN CRANES Ӏ SECTOR REPORT
j adjusted to balance transport
weight, set up space and tailswing restrictions, and lifting capacity, using Liebherr’s VarioBallast system. On the 300-tonner ballast can be set at 4.94 m or 5.94 m and is easily adjusted using a mechanical system. This allows the latest version of the crane, the LTM 1300-6.3, to achieve similar lifting capacities to the earlier 600t model, the LTM 1300-6.2, with 8t less ballast. That ballast can be secured on the crane’s turntable using Liebherr’s ‘one button’ Auto- Ballast system.
Wind speeds increase with height. The ‘canyon’ effect of skyscraper-lined city streets can further increase gusting. As the crane industry learned in the first years of widespread wind farm development, the effect of wind on loads can be catastrophic. So it makes sense that Liebherr should transfer some of the lessons learned from the wind energy sector to a tall city-focussed crane like this.
Liebherr has developed load
charts for different wind speeds, allowing work to continue, within safe limits, even when gusts exceed the 9 m/s that is typically the maximum for crane operations. The new load charts allow
operators to work at 11.2 m/s, or even 13.4 m/s, when using lattice equipment. In pure telescope mode, the tables even allow for a speed of 15.6 m/s. They are all stored on the crane’s control system computer, allowing operators to switch between them when needed. If the wind speed measured on the crane’s boom during a job exceeds the set chart wind speed, the crane operator can simply switch to a load chart with a higher maximum wind speed, Liebherr says, which will often allow the job to be continued.
Liebherr’s
VarioBase Plus on the LTM 1300-6.3
GOING 'EXTRA LONG' All of the most recent versions of cranes in this class offer substantially improved boom lengths compared to predecessors. As we’ve seen, a long boom can let you get to work quicker, and often means less loads needing to be carried to site. Today, all cranes in the 250-275t class offer at least a 60m boom, compared to the 50m that would have been standard a few years ago. In fact, only one crane in the
group – the Liebherr LTM 1250- 5.1 – reaches to just 60m. The Link-Belt ATC 3275 reaches 68m, and its bigger successor, the 275t 300|AT, reaches 72.5m. Manitowoc’s GMK5250L-1, along with Tadano’s AC 5.250-1 and upcoming AC 5.250-2, all offer a 70m main boom.
With the GMK5250XL-1,
Manitowoc has gone extra long. The five axle crane carries a hefty 78.5m main boom. That’s 8.5m longer than any other 250t crane, an extra 50cm of main boom reach compared to the six axle LTM 1300-6.2, and only slightly shorter than most other cranes in the six- axle, 300t class (with the exception of the new LTM 1300-6.3). The crane’s extra-long boom
allows it to be used flexibly, on a range of challenging job sites. Two recent tandem lift jobs by
22 CRANES TODAY
Spanish rental company Tinlohi demonstrate the wide range of requirements the crane can meet. On both jobs, one on a wind
farm and one at an industrial facility, Tinlohi used its XL crane alongside a GMK6400. On the wind farm, the company had been contracted to dismantle a turbine in Palencia, in north western Spain. The GMK6400 was rigged with 35t of counterweight to support its maximum 60m boom plus a 30m fixed jib. It lifted just over two- thirds of the load. Alongside it, the five-axle GMK5250XL-1 was also rigged with its maximum boom and fitted with a 9.4 m jib. The counterweight was 30.5t for the GMK5250XL-1 to manage its role in supporting one-third of the load. Components were lowered from a height of 90m. The company was able to complete the job in a day, including crane set-up. In nearby Valladolid, Tinlohi took on another dismantling job, this time at an industrial facility, where they were to remove a drying tube from a gasification plant. The cranes were set up to split the 55t load equally, with the larger crane set up with boom extended to 40m, and carrying 45t of counterweight, while the XL crane’s 72.5m boom was at 41.2m, with 65t of counterweight.
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