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BTB 21: Tackling Tough Terrain in Sweden

Tigercat finds niche in one of Sweden’s most demanding forest machinery applications.

— Paul Iarocci

In a demanding application where duty cycles approach 100% in soft ground, steep hills and rock strewn terrain, Tigercat has found a new market for its super-duty forwarders and six-wheel drive skidders. The country is Sweden, the application is ground scarification and the requirement is for high horsepower, durably constructed prime movers.

The discs float over the rocks as the scarifier moves across tough terrain.

Tough terrain. The discs float over the rocks.

In Sweden, the scarifying process generally involves the use of a disc or trenching attachment fitted to the rear of a heavy-duty carrier. The machine travels over a previously harvested tract, breaking through branches and tops left over from the harvesting process and creating rows of inverted turf. The mounded rows provide new trees with more light, water and access to nutrients, encouraging improved root formation.

In some cases saplings are manually planted on the edge of the mounds. In other cases, seeds are planted during the scarifying process using a system integrated into the attachment. Yet another method involves natural regeneration by seed trees left on the harvested area.

The rear bogie smooths out the ride as the machine moves over the rock strewn terrain.

The rear bogie smooths out the ride.

Tommy Olers, foreman for Akers Skog stands in front of one of their forwarders.

Tommy Olers, foreman for Akers Skog.

Tommy Olers, foreman for Akers Skog is operating one of the company’s two 1075 scarifiers fitted with a Bracke T26.a disc trencher attachment. At 205 kW (275 hp), the 20-tonne (22 tn) 1075 is Tigercat’s largest forwarder. It is quickly becoming regarded as the forwarder of choice for scarifying applications. Tommy is currently working the machine in southern Sweden near Filipstad where the ground will not freeze until January. At that time the machine can either be converted to a standard forwarder for the winter or Tommy can seek contracts to the south in more temperate Germany.

Akers Skog provides scarification services to forest industry giant Stora Enzo as well as a Swedish government-owned company. These companies try to place the 1075 scarifiers in sites with the most malevolent terrain and greatest amount of rock, recognizing there are few machines or contractors in Sweden that can handle these difficult contracts. Although it varies according to the terrain, the production rate averages one hectare (2.47 acres) per hour in tough ground.

The E625C is equipped with a three-row mounder.

The E625C is equipped with a three-row mounder.

Tommy puts in long days, routinely working 12-14 hour shifts. As the sole operator, he put 800 hours on the 1075 in the first two months. Spending that much time in the machine, comfort is an important factor. Tommy says that the double bogies and centre joint oscillation contributes to a significantly smoother ride over the rough ground. The bogies also lower the ground pressure, allowing the machine to work wetter, softer terrain.

Another advantage of the forwarder based scarifier is the crane. “I need the crane for balance and weight distribution for the middle and front of the machine. Also to move large trees and obstructions,” Tommy asserts.

The 1075 scarifier working on a challenging site for Stora Enzo. A near 100% duty cycle on steep terrain and rocks is extremely demanding on the machine.

The 1075 scarifier working on a challenging site for Stora Enzo. A near 100% duty cycle on steep terrain and rocks is extremely demanding on the machine.

The disc trencher is designed to float over rocks. “You must plan in advance where your path will be in order to avoid the large rocks. Smaller rocks are not a problem,” Tommy says. “The machine is very strong and well built. It can do work that no other machine can do.”

Kurt Collin, owner of F:a Kurt Collin and Per Tysk, owner of F:a Per Tysk Tyskgården both focus exclusively on scarification services. Kurt runs a new E625C with a rotating seat (now called the 635D) and son Per has the distinction of running the very first forwarder ever produced by Tigercat. This prototype 1018 model was converted to a scarifier when Per bought it back in 2005.

Kurt Collin sits inside the cab of a Tigercat skidder.

Kurt Collin likes the two-position rotating seat and rear drive controls.

The scarifying attachments invert the top layer of turf and soil to give new trees a higher survival rate.

The scarifying attachments invert the top layer of turf and soil to give new trees a higher survival rate.

Both machines are equipped with three-row mounders designed for sites with less rock cover. The mounder attachment creates intermittent patches of inverted soil as opposed to rows and doesn’t handle rocks as well as a disc-type trencher. Kurt and Per’s specialty machines are best suited to the mix of wet and hilly terrain encountered within a few hundred kilometres of Filipstad in the southwestern part of the country.

The relatively short skidder-based machine is easy to turn at the end of a row, increasing productive time. The two-position rotating seat and reverse drive controls also reduce end-of-row turn times. “The rotating seat is the best thing,” explains Kurt. He says that the skidder maintains quick travel speeds, routinely covering one hectare (2.47 acres) per hour.

As for ride quality Kurt says that the oscillating front axle combined with the rear bogie makes for a smooth ride and comments on the favourable weight distribution that allows him to tread lightly onto the soft, wet terrain that he often encounters.

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