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05.11.2008, 01:34 Uhr
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ALE finishes testing 4,300t SK 90
Abnormal Load Engineering has finished testing of its prototype 4,300t capacity SK 90, which is probably the largest construction crane currently in operation. ALE has built the crane for its exclusive use. It expects it to carry out its first job before the end of 2008.
Apart from heavy lift, the crane can also lift 2,600t in a luffing mode. Maximum boom length is 148m; a fixed jib section measures 48m. There are a total of eight different configurations with varied ballast radius and backmast lengths. The crane recently performed a test lift of 3,000t with an outreach (from the mainmast pin to the load) of 30m and 130m boom.
The crane takes a minimum crew of two. An operator controls the crane in a sightless control cabin; a supervisor/lift coordinator checks the movements. Maximum windspeed for lifting operations is 20m/s, although the team expects to work with an acceptable weather window of several days to make sure that no storms blow up.
The crane takes a team of 12 people 21 days to assemble and 18 days to disassemble. As tested, the crane required a set-up area of 200m by 35m. The boom assembles with hydraulically-activated pins. The total weight of the crane without counterweight is 1,600t, and breaks into 96 loads in standard open-top boxes, over-height boxes and flat racks. ALE has installed specially-designed counterweight containers, which can be loaded up to 100t each.
The crane uses four 900t off-the-shelf strand jacks with redundant sensors. Each jack takes 55 pieces of 18mm strand. A 600t capacity winching system can also be run through the mainmast to function as an auxiliary hook. The crane runs on electric motors powered by twinned 400 kVa diesel generators.
The crane raises the main boom with a patented chain system that ALE refers to as a topping lift. It consists of four hydraulic rams pulling on a plate link system. Each jack stroke is 800mm. This solution functions better than strand jacks, said ALE director Roger Harries: "We did not feel the strand jack arrangement is a good solution as the strand grippers collets often get clogged and the strand loses tension."
Maximum ground load under the counterweight is 34t per sq m, but this declines as the crane takes the weight of the load, to a minimum of 800t. Maximum load under the boom foot is 28t/sq m. "The ground preparation is very dependent on the terrain," Harries said. "If the ground can take the loading then the area has to be consolidated and made reasonably flat. We lay our mats on a sand bed of 150mm deep."
The company is planning to build and test a larger unit, the 120,000tm SK 120, by 2010.
Dieser Post wurde am 05.11.2008 um 01:34 Uhr von tc3000 editiert. |
