The 600t and 800t capacity all-terrain cranes have found a ready market among those involved in the erection of telecommunication masts and wind turbines. But for wind turbines at least, crawlers are beginning to take over and crawler crane manufacturers throughout Europe are increasingly taking account of the needs of the wind power industry when designing new machines.
The reason for this is that the nature of the wind power industry is changing from plants of one or two units to large windmill parks of 20 or more units. Therefore the big telescopic cranes are no longer as attractive as they were. They are too expensive to move from one unit to the next on the site because all the ballast has to moved as well. This operation is both time and resource consuming as several extra machines are needed to transport the ballast and boom, and extra cranes are needed every day to load and unload the parts. This is eliminated by using the crawler cranes.
New crawler models such as the Liebherr LR 1400/1 are specially designed for this particular industry, as many features – such as quick connection pins for the boom, the reaved blocks, which can stay on the crane during transport, and the semi-assembled stay rods and pins – reduce assembly/disassembly time of the crane.
Although the general perception is that a telescopic crane is faster to erect and cheaper to transport than a crawler, it is not entirely true anymore, as turbine tower heights creep up to 100m.
Liebherr’s LTM 1800 and LG1500 – ultimately the same machine fitted either with a telescopic or a lattice boom – require almost as many transport units, since neither can carry their own boom, or sections thereof. This is of course targeted by Mannesmann Dematic. The AC 500 and AC 650 can carry their own boom, and so only need transportation for the luffing jib and counterweight.
But none of these machines will be able to reach 100m, and so lattice-boom crawler cranes take over. It is not economically viable to erect one wind turbine with a large crawler, but as wind farms get bigger, the crawler becomes the obvious choice.
Mannesmann Dematic has also been targeting this industry, and both the CC 2500 and the CC 2800 will have a reasonably long lifespan in this industry. The CC 2500 more or less matches the LR 1400/1, and the CC 2800 outlifts both of them. The question of transport time is mainly concentrated on transport to and from site, as all cranes have the same ability to move around on site.
But for how long are these machines the solution? Some of the rental companies are already looking for alternatives, and the wind turbine manufacturers might soon be looking at a 3.0MW machine, with nacelles weighing more than 100t. This calls for either a different assembly method or the nacelle to be lifted in more pieces. Either way, new ideas or even bigger cranes will be needed.
