InfraStructures - September 2019 - CC 3800 Crawler Cranes Remove Rotor Blades from Wind Turbine Using Tandem Lifts

CC 3800 Crawler Cranes Remove Rotor Blades from Wind Turbine
Using Tandem Lifts

On behalf of Enercon, Belgian crane service provider Aertssen Group NV removed the rotor blades from an Enercon E-126 wind turbine at a height of approximately 136 m for maintenance. However, what may sound like a routine job was actually a tricky challenge, and it was only the team’s extensive experience and a pair of CC 3800 lattice boom crawler cranes that enabled them to successfully carry out the corresponding lifts.

“Before anything else, we had to decide which crane to use for the job,” reports Peter Bertels, Aertssen project manager. After all, there were 2 options available: either a large crane that would be able to take care of the lifts by itself or 2, more compact, cranes that would tackle the lift in tandem. Ultimately, the team decided on using its own CC 3800 cranes, as they were more cost-effective, would be powerful enough when used together, and had the required reliability and precision characteristics for the lifts. However, it was first necessary to make sure that the ground bearing capacities at the work site in Estinnes would be sufficient for the 2 crawler cranes, as they had originally been calculated back when the wind turbine had first been erected, for the use of a single crane only. Once the green light was given though, nothing else stood in the way of using the 2 units.

A total of 52 truck runs across a distance of approximately 130 km were needed in order to get the 2 cranes from the Aertssen Kranen branch in Stabroek to the work site. Once there, a 5-person team set up the cranes within a week.
The 72 t rotor blades not only had to be taken from a height of 136 m and safely lowered to the ground, but they also had to remain perfectly balanced while being lowered. To achieve this, the operator of the crane that was closer to the tower first guided a sling, which was hanging from a spreader beam with 4-part reeving, around the tip of the rotor blade. The operator of the other crane then repeated this exact same procedure. When “lassoing” the rotor blades with the slings, the 2 operators depended on the instructions of Enercon employees who were also on-site for the job.

“The reason is that even though we’d installed cameras on the spreader beams, our crane operators were operating remotely, and were therefore unable to determine whether the slings were at the right height. It was kind of like lassoing a tiny animal,” explains Mr. Bertels.

One week later after the required maintenance was complete, the rotor blades were reinstalled on the wind turbine.
Aertssen Group NV, which is headquartered in the Belgian municipality of Stabroek, was founded in 1964 as a small business by Marcel Aertssen. Today, the company’s fleet has more than 1,000 vehicles, including trucks, bulldozers, lowbed trailers, dump trucks, and cranes with lifting capacities of 25 to 750 t. In addition, Aertssen Kranen has all the transport vehicles, SPMTs, semis, and lifting equipment required in order to perform lifting work. Its state-of-the-art equipment and highly qualified team have enabled the company to have successful national and international operations in the areas of construction & infrastructure, crane services, and transportation & logistics.

Source: Terex Corporation

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