Allison automatic transmissions help New Zealand logging contractors improve efficiency and safety in the most difficult forestry conditions
WHANGEREI, New Zealand – Steep hillsides, narrow dirt tracks, green valleys and ancient forests abound 150km north of Auckland. This fantastic cinematic landscape played its own starring role in the popular movie trilogy, Lord of the Rings. In reality, the breathtaking topography presents an uncompromising challenge for a New Zealand company transporting pine logs from the forest floor to a ridge-top loading site.
In this rain-sodden forest, a Scania G44 8x8 truck equipped with an Allison automatic transmission gets the job done every time, under some of the harshest logging conditions imaginable.
For the last five years, Kiwi forestry contractor, Douglas Logging has employed the Scania truck to move logs over hills so slick with mud that they are difficult to negotiate on foot. On forestry tracks graded up to 40 percent, the Allison-equipped truck has proven to be the safest, most efficient way to move felled timber from areas that normal logging trucks can’t reach, to a point that on-highway timber jinkers can readily access.
As a logging contractor and the truck’s owner, Peter Douglas believes that the Allison transmission is a key factor in allowing the trucks to operate fully-laden and with relative ease. “It goes places where no normal log truck would ever dare venture – enabling us to quickly move logs out of inaccessible areas to a skid site where we can load them onto a normal truck.”
Douglas added that the Allison transmission’s ease of operation in such tricky conditions was a major factor in its selection. “It’s just so much easier to drive. We don’t swap drivers often, but when necessary, we know a less experienced driver can more easily master the automatic as compared to a manual, which we have proven with a MAN truck we used in similar circumstances.”
“The synchromesh was badly damaged doing similar work, because the driver has to quickly grab a gear to preserve momentum, which means we have to pull out the gearbox, a problem we won’t have with the Allison,” he added. “You also haven’t got the added problem of worn clutches, another consideration with heavy loads on steep grades and in muddy conditions.”
Heavy rainfall throughout New Zealand’s winter makes traction especially challenging in the Puoto Forest. However, according to Douglas Logging, the Allison-equipped truck has never gotten stuck. The Scania always gets its load to the skid site at the summit without bother. At that point, manoeuvrability in precariously tight turning areas can literally be a matter of life and death. The Scania’s regular driver, Karl Thompson, says that the automatic’s smooth launch makes his work, not just easier, but much safer.
In the loading area, Thompson must turn the truck toward the edge of a high ridge, requiring parts of his cab to dangle over a sheer drop – with nothing separating his vehicle from the valley hundreds of metres below. He then makes a multi-point turn to position the truck for loaders.
“It certainly calls for a good deal of trust in the Allison transmission; any snatching or jerks in the take-up when close to the edge could spell disaster,” said Thompson. “The Allison doesn’t jump or lurch and is very predictable.”
Reliable, too. The Douglas Logging Scania has been in almost constant use, making 15 to 18 (300-500 metre) trips daily, moving an average of 450 tonnes. Perhaps that’s why the company recently added another Allison-equipped Scania truck, identical to the first.
“The whole point is to improve efficiency –in the operation’s hilly areas like this Pouto Peninsula forest,” said Douglas. “If you used a log forwarder it would be really slow, and it would badly damage the road.”
The hub reduction front-drive axles are rated at nine tonnes each, and the hub-reduction rear axles feature a 5.14:1 ratio, with a combined 32 tonne rating. The driveline package sees a 440-horsepower Scania DC13 Euro 5 EGR engine mated to the Allison 4500 six-speed automatic transmission.
“With diff-locks selected and the Allison locked into first gear, the rest is easy. You start in first and stay in first, and just keep it at around 1700rpm. That is the only way to do it safely,” finished Thompson.