Bolk Transport B.V. and Universal Transport have recently opted for DOLL’s self-steering trailer combinations. Both chose hydraulic lifting adapters on a dolly, giving themselves enough reserve capacity to accommodate the steady increase in rotor blade length and weight that the industry is experiencing. With a dead weight of approximately 7.0 to 7.3 tons (depending on the choice of equipment) and a maximum fifth-wheel load of 30 tons, the dolly has a remaining load capacity of around 23 tons. Working at the other end of the system, the four-axle vario self-steering trailers boast a load capacity of around 32 tons with a total technical weight of 40 tons. These trailer combinations are able to accommodate an extensive range of rotor blade sizes, even those approaching the 100-metre mark.
The Netherlands-based Bolk Transport put three of these systems into operation a few weeks ago. “We collected the last two before Christmas”, says managing director Joop Savenije. “Wind turbines have three blades, but it’s not like you transport one to its destination, then go back for the other two”, he adds. “So you need three vehicles – one for each blade.” Previously, Bolk had relied solely on telescopic trailers to transport wind power components. As rotor blades began growing to more than 65 metres in length they had to find an alternative solution. “We’re now increasingly seeing blades approaching 75 metres long – and they’re getting heavier too”, says Savenije. In mid-January, the Seaport of Brake in Germany provided the location for the first trial loading operation, with Bolk project manager Emil Leushuis monitoring the progress and taking notes. “What makes the trailer technology so good is that the rotor blade is self-supporting and there are much more flexible options for navigating obstacles. There’s also a tiltable lifting adapter at the front, and the equipment is able to get round bends much more smoothly. The extensive slewing angle and attached turntable make it possible to position the dolly and self-steering trailer at an almost entirely transverse angle to the bolster, while the vehicle keeps on going”.
The specialists at Universal Transport in Paderborn, Germany have been making use of their three latest DOLL self-steering trailer combinations since August 2020. Driver Ronny Knoblauch commented: “We’re currently using the trailers to carry rotor blades measuring as much as 65 metres long, on vehicles with a total length of up to 77 metres. The extendable cable and rope systems provide 120 metres in length, so there’s practically no limit to how far you can take the system – which isn’t the case with telescopic trailers. As there’s no telescopic beam, you’re left with much more room to cross over obstacles underneath the load. That means we don’t have to move nearly as many crash barriers aside when we encounter them on our outward and return journeys. The system is also a lot more agile. I can navigate roundabouts relatively easily with the traction unit and dolly, for instance, and the self-steering trailer simply follows me round. The turntable on the trailer gives you a huge slewing range at the rear, so you can keep driving straight at the front for a long time. The nature of the system means it’s even more important to have a second person involved so that they can give you feedback and intervene in the steering at any time – but on the whole, the handling is much smoother than it is in a telescopic trailer. And the system’s actually fun to drive”. The hydraulic lifting adapter on the dolly also has a vital role to play: “I can release it by as much as 80 centimetres, which is handy in situations like manoeuvring over a traffic island or crouching down to road level to get under a low sign gantry”.