Reaching into the depths

A huge cloud of mud spreads out in the water in front of the high dam wall of Lago di Luzzone in the Swiss canton of Ticino. With a gurgle, the bright red clamshell grab, which weighs over a tonne, rises out of the water, sending a fountain of water soaring up several metres high. The powerful metal fist, which Yann Blouet, one of two crane operators, controls almost playfully with a kind of joystick, holds ten cubic metres of mud and debris. He navigates it to the loading area of the lighter, a ponderous transport vessel, which has drawn up right alongside the crane. The grab opens and releases its wet load. "I dredge sediment out about twelve times an hour," says Blouet. "The handling volume is huge."

By 2018, the duty cycle crawler crane supplied to the French construction company S.E. Levage will have dredged as much as 125,000 cubic metres of material out of the reservoir. The reason for doing this: The power plant in nearby Olivone that is connected to the reservoir does not obtain sufficient water pressure if debris and sediment block up the filter grid in front of the outlet. As this cannot be completely prevented in this high-alpine environment, the power plant has been shut down in the summer months for three consecutive years. The Liebherr HS 8130 HD duty cycle crawler crane, which is firmly anchored on a barge close to the dam wall, can then begin its work. The crane brings considerable power to the task: the engine has a power rating of 505 kW, the crane's lifting capacity is 130 tonnes and its tractive power is 2 x 350 kN. Depending on the depth at which it is working, the XXL machine at the reservoir in Switzerland can handle up to 130 cubic metres an hour.

  • Huge chunks of rock
    Yann Blouet doesn't find out what he has got hold of down there at a depth of 150 metres until he has hauled the special grab up from the bottom of the reservoir. Besides a lot of muddy sediment, there may also be huge boulders. They will now no longer block the outflow.

    Huge chunks of rock

    Yann Blouet doesn't find out what he has got hold of down there at a depth of 150 metres until he has hauled the special grab up from the bottom of the reservoir. Besides a lot of muddy sediment, there may also be huge boulders. They will now no longer block the outflow.

  • Specially manufactured
    The special grab from Negrini was optimized specifically for use in Ticino and has a load capacity of ten cubic metres.

    Specially manufactured

    The special grab from Negrini was optimized specifically for use in Ticino and has a load capacity of ten cubic metres.

  • Duty cycle crawler crane operator Yann Blouet
    For crane operator Yann Blouet, this work high up in the Alps is always a great experience.

    Duty cycle crawler crane operator Yann Blouet

    For crane operator Yann Blouet, this work high up in the Alps is always a great experience.

  • Lago di Luzzone
    Lago di Luzzone is a reservoir at the upper end of the Blenio valley. The top of the dam lies at 1,609 metres above sea level and the water in the lake at its lowest level lies at 1,435 metres.

    Lago di Luzzone

    Lago di Luzzone is a reservoir at the upper end of the Blenio valley. The top of the dam lies at 1,609 metres above sea level and the water in the lake at its lowest level lies at 1,435 metres.

  • The challenge here is the depth from which the sediment has to be dredged up. We go down as far as 200 metres to the bottom of the lake.

    Fascination of the depths

    Yann Blouet, who with his goatee and moustache looks a little like his rock idol Frank Zappa, is fascinated by his workplace at 1,600 metres above sea level: "The challenge here is the depth from which the sediment has to be dredged up. We go down as far as 200 metres to the bottom of the lake," he explains.

    Up here, surprises are part and parcel of a crane operator's job description: for example, the work can be hampered by wind, heavy rain and rockfalls or a sudden deterioration in the weather. Blouet sometimes also dredges up a surprising or unpleasant load, such as a dead animal – a sheep, a deer or a chamois which has slipped off the smooth rocks into the lake and drowned. Often there are also really large trees or rocks that have to be removed from the underwater grid.

    "The grab takes several minutes to get to its deep underwater dredging point," says Blouet. Nothing can be seen down there. "I feel it with the grab." Blouet's hands clasp the joystick in the cockpit as he glances at the monitor with the GPS display that uses coloured bars to show him the depth at which the grabber is located. Blouet operates the control lever at the current depth of 150 metres: once again, he is moving a little closer to his target of having completely cleared the grid to a depth of 200 metres.

    Investing a lot of power to obtain more energy

    Logistics

    Precision work

    How do you get a crane through the eye of a needle? Transporting the duty cycle crawler crane to its operating site in the Ticino Alps was an adventure and a technical masterpiece in terms of logistics.

    The duty cycle crawler crane is flexible and can be deployed almost anywhere. However, the construction site at Lago di Luzzone is far from being an ordinary location. The reservoir lies at 1,600 metres above sea level at the upper end of the Blenio valley. The route to the dam wall follows a narrow road winding uphill. It poses a genuine challenge in terms of transport logistics and calls for precision planning, literally to the millimetre.

    How can the exceptionally long articulated lorry manage the hairpin bends? How can the dismantled crane be driven up the valley road out of Val Carassino and manoeuvred through two tunnels? One is damp and cold, the other long and dark. "On top of this, there is the threat of falling rocks due to heavy rain," says Paul Hotz from the logistics company JMS-RISI, outlining the risks.

    Prior to transportation, the logisticians had prepared templates which they used for measuring the narrow passages in the tunnels and for planning how to negotiate the hairpin bends on mountain roads with 300-metre drops down spruce-covered slopes, and manage the journey over the dam wall, which is just under 225 metres high. "Everything went smoothly," says Hotz, evidently relieved to have completed the challenging delivery.

    Assembly

    The "assembly kit"

    How do you put together a duty cycle crawler crane of this size in the mountains? With a lot of skill and expertise and forward planning. At the reservoir, the water has been drained. But it's bucketing down. The rain is running off the workers' hats into their faces. But no-one seems bothered. The team is highly focussed. The upper and lower carriages of the delivered duty cycle crawler crane are being put together by Liebherr experts. This calls for absolute precision work. Crane operator Blouet is also involved. Working from the cab, he holds the individual parts in place. The crawler crane is then placed first on a platform and then on the barge on the bottom of the lake. Overnight, the lake is flooded, and the barge, with the machine, rises and floats to the operating site. Blouet will spend two more summers ensuring that the power plant regains full hydropower capacity.

    Features

    The specialist

    The HS 8130 HD duty cycle crawler crane was manufactured in spring 2016 at Liebherr's site in Nenzing, Austria. It has two hydraulic free-fall winches, each with a line pull of 35 tonnes – approx. 17 per cent more than in the predecessor model (HS 885 HD). "The outstanding features of the duty cycle crawler crane are its 200-metre winch capacity and its higher rope speed, which is automatically adjustable using a dual motor," says Florian Gabriel, Product Manager for Liebherr at Nenzing. In three months, we had built the machine and fitted it with a clamshell grab specially designed for the assignment in Ticino. This flame-red tool from Italian grab specialist Negrini has a filling capacity of ten cubic metres. The grab manages an average handling capacity of 130 cubic metres per hour.

    An average of 180 million cubic metres of water flows through Olivone power plant's turbines each year. Around 234,000 megawatt hours of energy are generated in this way. The same water then flows on to the Bianca power plant and generates a further 304,000 megawatt hours of electricity there. The power plant thus makes a substantial contribution to the region's electricity supply. Provided, that is, that the water can pass unimpeded through the outlet.

    "At first, the operators planned to use a crawler crane to do the dredging work," says Florian Gabriel, referring to the initial plans. But on closer inspection, he quickly realised: "You need a duty cycle crawler crane." Otherwise, it would have been impossible to achieve the high throughput of sediment that was required. "The 200-metre winch capacity and the higher speed are essential for this job," says Gabriel. Another key factor in the award of the contract was Liebherr's servicing and customer service provision in Switzerland, involving relatively short journeys to the reservoir from the plant in Austria or from the Swiss distribution and service company's site.

    Out on the lake, Yann Blouet is not alone

    Every morning at six o'clock, the crane operator and a boatman go out to the barge in a small boat. Blouet checks the crane's oil gauge and the measurement level and lets the engine warm up for a few minutes. In the cab, he has put on "some quiet background music" which allows him to forget that he is alone in the cab in this alpine mountain world.

    The day begins. The boatman moors the lighter against the barge, receives the load from the dredger's grab once, twice, waits until the lighter is full and then takes the load to the other end of the lake. It will be half an hour until he returns. In the meantime, Blouet fills the lighter on the other side of the barge.

    A fascination with technology

    Dredging in the lake is not possible in the winter. Yann Blouet then has time to call in at the Liebherr plant in Nenzing. Even after almost twenty years of experience in the job, he is still enthusiastic about the processes used there in the production of the various crawler cranes, duty cycle crawler cranes and piling and drilling rigs. "I find anything to do with technology interesting," says Blouet. In the plant, the sparks fly up into the dark air in the production shop. The building is as tall as an aircraft hangar. A fitter cuts metal sheets for the vehicles. The "boom" and the "needle", the two arms of a duty cycle crawler crane, lie on the bare floor as if in a state of slumber. Blouet talks shop with the workers, showing interest in every detail, however small. This goes down well at the plant. "After all, quality is important to all of us," says Blouet. This applies as much to the design, production and processing as it does to ensuring absolutely safe and reliable use in the often harsh conditions of day-to-day work.

  • A passion for large-scale technology
    Welding sheets: In Nenzing in the middle of the Alps, Liebherr crawler cranes, duty cycle crawler cranes and piling and drilling rigs are designed and assembled.

    A passion for large-scale technology

    Welding sheets: In Nenzing in the middle of the Alps, Liebherr crawler cranes, duty cycle crawler cranes and piling and drilling rigs are designed and assembled.

  • Behind the scenes
    Duty cycle crawler crane operator Yann Blouet looks around the site in Nenzing, where his machine comes from. "I find anything to do with technology interesting", says Blouet

    Behind the scenes

    Duty cycle crawler crane operator Yann Blouet looks around the site in Nenzing, where his machine comes from. "I find anything to do with technology interesting", says Blouet

  • Exchange of experiences
    The workers and engineers in Nenzing appreciate his visit. In this way, they get first-hand information about everything that their duty cycle crawler crane has to do up in the Ticino Alps.

    Exchange of experiences

    The workers and engineers in Nenzing appreciate his visit. In this way, they get first-hand information about everything that their duty cycle crawler crane has to do up in the Ticino Alps.

  • Underway in style
    Photo souvenir: Yann Blouet has taken a particular shine to the crawler cranes. In 2013, a crawler crane from Nenzing set a world record. The LR 1300 lifted what at that time was the world's widest tilt-up concrete panel, measuring 27 metres.

    Underway in style

    Photo souvenir: Yann Blouet has taken a particular shine to the crawler cranes. In 2013, a crawler crane from Nenzing set a world record. The LR 1300 lifted what at that time was the world's widest tilt-up concrete panel, measuring 27 metres.

  • I enjoy working in this environment with its unparalleled combination of technology and nature.

    Yann Blouet

    Back to Lago di Luzzone. Blouet is dredging close to the reservoir dam. But the crane operator is not entirely happy with what he is lifting out. The monitor shows a distance of twenty metres from the outflow grid. Blouet reaches for the walkie-talkie and calls to the barge operator behind him: "Move closer in!" The barge moves forward slowly. Only another ten metres or so to the wall. Blouet lets the grab shoot down. Blouet's dredger, with its 32-metre-long boom, is now almost dwarfed by the more-than-200-metre-high concrete wall looming over it.

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    Duty cycle crawler cranes

    Duty cycle crawler cranes

    Liebherr crawler cranes can be used in a wide range of applications. They are ideal for materials handling with grabber and drag bucket and equally for dredging excavation and demolition work.

    Liebherr duty cycle crawler cranes