Two six-axle Grove cranes complete tandem lift in New Zealand

When one of the world’s largest paper and pulp facilities needed a new barking drum, two of Manitowoc’s six-axle Grove all-terrain cranes were called into action to hoist the 84 t load into position at a challenging job site in Kawerau on New Zealand’s north island. With tight clearances, on-site obstacles and limited space to set-up, the two cranes worked perfectly in tandem, offering an ideal solution to a difficult lifting problem.

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The Tasman Mill is in operation 24 hours a day, seven days a week, and processes over 1.1 million t of wood every year. Pedersen’s Industries took over the management and operation of the log yard and chip mill in 2004, and recently decided to upgrade the debarking system. National crane hire specialists, Pollock & Sons Crane Hire Ltd, were chosen to supply the lifting equipment from its range of 10 Grove cranes.

The two largest cranes in the fleet – the Grove GMK6400 and the Grove GMK 6300L – were transported from Pollock & Sons’ headquarters in Tauranga, 100 km away, to carry out the delicate operation. Not only did the operators have to be mindful of the underground constraints, such as pipe work and drainage systems, but also aboveground obstacles including buildings situated in close proximity.

Before installing the new drum, the old system was removed in four loads, each weighing around 62.5 t. The log decks were also removed, weighing between 35 t and 55 t per load. For these operations, the GMK6400 was configured with a full counterweight of 135 t and its MegaWingLift capacity enhancing attachment, which increases lifting capacity for the crane by up to 70% for some boom positions. Like the GMK6400, the GMK 6300L was also equipped with its full complement of counterweight, 92.5 t.

“Both of the cranes offered quick set-up times and the rigging was straightforward, which allowed us to move the cranes around the site with minimal downtime,” explains Carl Hawkings, dispatch operations at Pollock & Sons. “The MegaWingLift attachment on the GMK6400 allowed us to achieve greater capacity when working with longer boom lengths – and without it, the lifts on this project wouldn’t have been achievable. The customer was very pleased with the efficiency of our operations.”

The MegaWingLift attachment on the 400 t capacity GMK6400 helps the crane achieve its superior lift capabilities by providing extra support to the boom. It also has a patented self-rigging system that mounts on the chassis and connects to the boom. When the boom is in the working position, the MegaWingLift extends laterally to stiffen the boom, allowing it to lift greater loads. As well as the best load chart in its class, the GMK6400 offers a 60 m main boom that can be extended to 134 m with a luffing jib, enabling it to perform lifts that are not possible with any other six-axle crane.

Meanwhile the 300 t capacity GMK6300L offers the longest boom in its class at 80 m and this can be extended further still with its 37 m jib. Despite offering exceptional reach the crane is also relatively compact and offers excellent on-site flexibility with a choice of five available outrigger positions, more than any other crane in this capacity class, giving ultimate flexibility, even in the narrowest of sites.

Once the two cranes had worked separately to remove the old debarker, it was time to work together to lift into place the new 84 t barking drum, which measured 25 m long and 3.7 m in diameter. With limited space on site, the drum was lifted between the two cranes at a height of 13 m to clear the buildings, leaving minimal clearance between the GMK 6300L’s boom and the nearest obstacle.

“Our biggest challenge was bringing the drum between the two cranes and rotating it without touching either boom, which would have resulted in damage,” Hawkings explains. “With the two cranes’ differing swing radiuses and lift capacities, a considerable amount of time and planning went into the lift. But our expert team and trustworthy equipment enabled us to complete the tandem lift successfully.”

Once the drum was in place, the chutes that feed logs into the drum, each weighing between 50 t and 60 t, had to be installed. Now that the new system is successfully up and running, the logs are fed along a conveyor belt into the rotating drum and the bark is stripped as the logs tumble against one another and the ribbed sides of the drum.

“At Pollock & Sons, we’ve nicknamed our GMK6400 ‘King Crane’, because it really is the ultimate heavy lifter taxi crane in our fleet,” adds Hawkings. “And the GMK 6300L is affectionately named ‘Brutus’. Brutus has been an asset since we purchased him in May 2011 with his fast set-up and versatility on construction sites.”

Other Grove all-terrain cranes in the Pollock & Sons fleet are: one Grove GMK6220L, one GMK5170, two GMK5130s, one GMK4100 and two GMK3060s, while the company also operates a TMS875 truck crane. The company’s fleet operates across the areas of Auckland, Hamilton, Tauranga and Kawerau.