On the drawing board at Spierings in the Netherlands is a 240 tonne-metre mobile folding tower crane on a seven axle carrier. The SK2400-AT7 will extend the range upwards from the current flagship model SK1265-AT6 on six axles. At the time of writing in early January, fabrication of the first prototype was due to start in the next few weeks and the first unit should be ready towards the end of 2006, explained Spierings' Bob Bruijsten.
Maximum load at the end of the 42 m (137 foot) jib is 5.5 tons (on two falls of rope) and the maximum load of 20 tons (on four falls) is shown on the chart out to 13.4 m (44 feet) with the three section lattice jib horizontal. While the available specification is preliminary, the numbers are “more or less definite, and if any change they will only be more,”Bruijsten explained.
Orders have been received for five units, Bruijsten said, and typical buyers are large mobile crane rental companies. Applications will include “heavy lift tower” work, for example, placement of concrete precast elements at maximum radius.
Between the outriggers, where there are five axles, the chassis is like the six-axle model, the difference being that there are two axles at the front on the new model instead of one on the SK1265. Running at 13 tons per axle, including outrigger pads, etc., the additional axle allows more counterweight to be carried on board for more lifting capacity. Overall lengThis 16.865 m (55 feet) compared with 16.279 (53 feet) for the six-axle - a smaller increase than might be expected, due less boom head overhang at the front.