Equipment Specs


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Forestry Equipment
2004 John Deere 2054 Delimber
Delimbers, normally mounted on hydraulic excavators, are used to remove branches from felled trees in the forestry industry.[1] Since their early beginnings, various types have been developed, including chain flail, gate, slideboom, stroke, and pull-through delimbers.


[edit] History

The precursor to delimbing machines was the method of hand-limbing trees, using a hand tool such as a saw. As the need for more efficient delimbers presented itself, developments were made in mechanized processing. The first delimbing machine prototype was introduced in 1953 by Oksa-Olli of Finland, but was not terribly efficient, and therefore did not gain much success. This delimber weighed 551 pounds (250 kg), had a three horsepower engine, and could only delimb trees that were under 4.3 inches (11 cm) in diameter.[2]

[edit] Chain Flail Delimbing: The First Attempt

An early type of delimbing process employed the chain flail method. Essentially, the flailing action of chains attached to a rotating drum would beat the limbs off of trees that were brought to it by a Michigan PL-75 skidder. One of the first such attempts was made at the Ontario Paper Co. in Heron Bay, Ontario,[3] but it remained experimental.

1996 Valmet 911 6x6 Harvester

[edit] Full-tree Harvester Delimbing

In the late 1950s, delimbing was often accomplished using full-tree harvesters. These harvesters would do many jobs including falling, skidding, and delimbing. One such machine was developed by John Pope of North Western Pulp & Power. Pope’s harvester, mounted on a crawler tractor, would rotate a newly-felled tree into a horizontal position before laying it into a delimbing head that would shear off the limbs. The drawback of machines such as these was the fact that they had to drive right up to a tree in order to operate.

An improved harvesting machine was developed in the early 1960s by Bob Larson, maker of the Hiabob knuckleboom loader. His harvester employed a function in which a knuckleboom could reach out from a tractor and delimb a tree with a set of knives before topping and falling it with a shear.

Other harvesters were manufactured from the 1960s, such as the Koehring-Waterous Model IIIB which held a tree at its butt while moving a delimber up the stem.

[edit] Kockums Processors

In 1967 Swedish company Kockums developed a processor he named the Logma. This processor really only did the job of a delimber. It consisted of two cabs, one of which contained controls for moving the machine, and the other of which contained those that operated the processor. This machine had a long boom that fed a log through a set of knives. This machine would gain popularity in the early 1970s, as a Swedish forest company by the name of Doman ordered 125 of these machines.[4]

Shortly after this offering was introduced, Kockums developed the Skruven, which had rotating spirals. This machine operated in such a way that delimbed logs would have to be removed immediately, or they would be reduced to thin sticks. This machine was never developed beyond its prototype stage. It wasn’t until early 1970 that Kockums would introduce more successful production model delimber.

[edit] The Need for a Better Delimbing Process

As the various processes in logging became mechanized, delimbing became a major issue for operators. Workers delimbing trees with power saws could not keep up with the volume of logs being deposited by a grapple skidder and feller-buncher. This laborious task was also dangerous, as men were working among heavy machinery.

[edit] Delimbing Gate

In response to the need for a more efficient machine, delimbing gates were developed. These machines consisted of a vertical grid made of welded pipe. A grapple skidder would bring a full turn of trees into area, and back the trees through the gate. Through this process, limbs were bent backward and broken off.[5] This method was most effective on pine trees.

[edit] Features/Types/How it Works

[edit] Flail Delimbers: The Next Generation

In 1972, Gordon Franklin, the equipment manager for Manitoba Forestry Resources Ltd, developed a new kind of flail delimber.[6] This flail was mounted on the front of a skidder, which drove over several trees simultaneously to remove all their limbs at once. This machine was produced for commercial purposes for a few years, but was never entirely successful, as it could never fully delimb all the trees’ branches.

[edit] Slide Boom Delimber

1988 Komatsu PC200LC 3-Stroke Delimber
In the mid-1970s, slide boom delimbers, also known as hydraulic stroking delimbers, were developed. By the 1980s, these devices were frequently used on large contractor and company jobs. Slide boom delimbers, with processing times between two and four trees per minute, were normally mounted on tracked excavators, operating on a haul road, on windrows full of trees. The first such machine was Sweden’s Logma T-310, consisting of a boom 23-foot (7-m) stroke with two hydraulic delimbing knives.[7] The Logma T-310 would delimb by moving the tree through a holding device and reclamping, enabling an entire tree to be processed regardless of height. Other slide boom delimbers were introduced in the late 1970s by companies such as Roger and Harricana.

[edit] Stroke Delimber

The first stroke delimber, also known as a stick delimber, was developed in 1977 in Sweden.[8] This machine was a complete unit mounted on a rubber-tired frame. Operating in a similar fashion as the harvesting machines developed in the 1950s and 60s, this delimber picked up a tree by its top while delimbing knives were pushed down the stem with a boom. As many Canadian companies came out with less expensive versions of this delimber, it had almost completely replaced the flail delimbers by the 1980s.[9]

[edit] Pull-through Delimber

By the early 1980s, a simpler and cheaper delimber became available: the pull-through type. This machine, set up at the landing, had a set of delimbing knives mounted on a frame. During the loading process, trees were pulled through the delimber by a knuckleboom loader before being stacked into a truck. One of the first companies to manufacture the pull-through delimber was CTR Manufacturing;[10] today, other North American companies, such as Bell and Morbark, also offer these machines.

[edit] Common Manufacturers

[edit] Additional Photos

Waratah HTH24 Super Processing Head
1998 Komatsu PC220 LC Processor
1998 Tigercat 845B Processor

[edit] References

  1. Ritchie Bros. Auctioneers. Equipment Valuation Assistant. Ritchie Bros. Auctioneers Incorporated: 2004.
  2. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  3. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  4. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  5. Stenzel, George and Walbridge Jr, Thomas A. and Pearce, J. Kenneth. Logging and Pulpwood Production. John Wiley Sons: 1985.
  6. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  7. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  8. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  9. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.
  10. Drushka, Ken and Konttinen, Hannu. Tracks in the Forest. Timberjack Group Oy: 1997.

[edit] Additional Resources

  • Conway, Steve. Logging Practices. Miller Freeman: 1982.
  • Creighton, Jeff. Logging Trucks, Tractors, and Crawlers. Motorbooks International: 1997.
  • Tsoumis, George. Harvesting Forest Products. Stobart Davies: 1992.