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A harvester is a type of heavy forestry vehicle employed in cut-to-length logging operations for felling, delimbing and bucking trees. A forest harvester is typically employed together with a skidder that hauls the logs to a roadside landing, for a forwarder to pick up and haul away.
Forest harvesters were mainly developed in Sweden and Finland and today do practically all of the commercial felling in these countries. The first fully mobile timber "harvester", the PIKA model 75, was introduced in 1973 [1] by Finnish systems engineer Sakari Pinomäki and his company PIKA Forest Machines. The first single grip harvester head was introduced in the early 1980s by Swedish company SP Maskiner. Their use has become widespread throughout the rest of Northern Europe, particularly in the harvesting of plantation forests.
Before modern harvesters were developed in Finland and Sweden, two inventors from Texas developed a crude tracked unit that sheared off trees at the base up to 0.76 meters (30 in) in diameter was developed in the US called The Mammoth Tree Shears. After shearing off the tree, the operator could use his controls to cause the tree to fall either to the right or left. Unlike a harvester, it did not delimb the tree after felling it. [2]
Harvesters are employed effectively in level to moderately steep terrain for clearcutting areas of forest. For very steep hills or for removing individual trees, ground crews working with chain saws are still preferred in some countries. In northern Europe small and manoeuvrable harvesters are used for thinning operations, manual felling is typically only used in extreme conditions, where tree size exceeds the capacity of the harvester head or by small woodlot owners.
The principle aimed for in mechanised logging is "no feet on the forest floor", and the harvester and forwarder allow this to be achieved. Keeping workers inside the driving cab of the machine provides a safer and more comfortable working environment for industrial scale logging.
Harvesters are built on a robust all-terrain vehicle, either wheeled, tracked, or on a walking excavator. The vehicle may be articulated to provide tight turning capability around obstacles. A diesel engine provides power for both the vehicle and the harvesting mechanism through hydraulic drive. An extensible, articulated boom, similar to that on an excavator, reaches out from the vehicle to carry the harvester head. Some harvesters are adaptations of excavators with a new harvester head, while others are purpose-built vehicles.
"Combi" machines are available which combine the felling capability of a harvester with the load-carrying capability of a forwarder, allowing a single operator and machine to fell, process and transport trees. These novel type of vehicles are only competitive in operations with short distances to the landing.
A typical harvester head consists of (from bottom to top, with head in vertical position)
One operator in the vehicle's cab can control all of these functions. A control computer can simplify mechanical movements and can keep records of the length and diameter of trees cut. Length is computed by either counting the rotations of the gripping wheels or, more commonly, using the measuring wheel. Diameter is computed from the pivot angle of the gripping wheels or delimbing knives when hugging the tree. Length measurement also can be used for automated cutting of the tree into predefined lengths. Computer software can predict the volume of each stem based on analysing stems harvested previously. This information when used in conjunction with price lists for each specific log specification enables the optimisation of log recovery from the stem.
Harvesters are routinely available for cutting trees up to 900 millimetres (35 in) in diameter, built on vehicles weighing up to 20 metric tons (20 long tons; 22 short tons), with a boom reaching up to 10 metres (33 ft) radius. Larger, heavier vehicles do more damage to the forest floor, but a longer reach helps by allowing harvesting of more trees with fewer vehicle movements.
The approximate equivalent type of vehicle in full-tree logging systems are feller-bunchers.
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Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. In forestry, the term logging is sometimes used narrowly to describe the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard. In common usage, however, the term may cover a range of forestry or silviculture activities.
Lumberjack is a mostly North American term for workers in the logging industry who perform the initial harvesting and transport of trees. The term usually refers to loggers in the era before 1945 in the United States, when trees were felled using hand tools and dragged by oxen to rivers.
A chainsaw is a portable handheld power saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar.
A loader is a heavy equipment machine used in construction to move or load materials such as soil, rock, sand, demolition debris, etc. into or onto another type of machinery.
Heavy equipment, heavy machinery, earthmovers, construction vehicles, or construction equipment, refers to heavy-duty vehicles specially designed to execute construction tasks, most frequently involving earthwork operations or other large construction tasks. Heavy equipment usually comprises five equipment systems: the implement, traction, structure, power train, and control/information.
A forage harvester – also known as a silage harvester, forager or chopper – is a farm implement that harvests forage plants to make silage. Silage is grass, corn or hay, which has been chopped into small pieces, and compacted together in a storage silo, silage bunker, or in silage bags. It is then fermented to provide feed for livestock. Haylage is a similar process to silage but using grass which has dried.
A skidder is any type of heavy vehicle used in a logging operation for pulling cut trees out of a forest in a process called "skidding", in which the logs are transported from the cutting site to a landing. There they are loaded onto trucks, and sent to the mill. One exception is that in the early days of logging, when distances from the timberline to the mill were shorter, the landing stage was omitted altogether, and the "skidder" would have been used as the main road vehicle, in place of the trucks, railroad, or flume. Modern forms of skidders can pull trees with a cable and winch, just like the old steam donkeys, or with a hydraulic grapple either on boom or on the back of the frame (clambunk skidder).
Cut-to-length logging (CTL) is a mechanized harvesting system in which trees are delimbed and cut to length directly at the stump. CTL is typically a two-man, two-machine operation with a harvester felling, delimbing, and bucking trees and a forwarder transporting the logs from the felling to a landing area close to a road accessible by trucks.
A forwarder is a forestry vehicle that carries big felled logs cut by a harvester from the stump to a roadside landing for later acquisition. Forwarders can use rubber tires or tracks. Unlike a skidder, a forwarder carries logs clear of the ground, which can reduce soil impacts but tends to limit the size of the logs it can move. Forwarders are typically employed together with harvesters in cut-to-length logging operations. Forwarders originated in Scandinavia.
A feller buncher is a type of harvester used in logging. It is a motorized vehicle with an attachment that can rapidly gather and cut a tree before felling it.
Limbing or delimbing is the process of removing branches from a standing or fallen tree trunk.
A bucket-wheel excavator (BWE) is a large heavy equipment machine used in surface mining.
Ponsse Plc is a company domiciled in Finland that manufactures and markets a range of forestry vehicles and machinery such as forwarders and harvesters. The Ponsse company was established by the forest machine entrepreneur Einari Vidgrén in 1970. Today, Ponsse's machines are used at logging sites in approximately 40 countries, and 80 per cent of the company's net sales come from exports. All machines are manufactured in the company's birthplace in Vieremä. Ponsse Group employs more than 1,800 people in 10 countries, and the company's shares are quoted on the NASDAQ OMX Nordic List.
Sakari Pinomäki (1933–2011) was a Finnish systems engineer and an inventor, who pioneered the mechanized forestry industry. He was the founder of PIKA Forest Machines which produced the first purpose-built forest machine in 1964 in Ylöjärvi , Finland. His inventions had over 50 patents.
A heavy equipment operator operates heavy equipment used in engineering and construction projects. Typically only skilled workers may operate heavy equipment, and there is specialized training for learning to use heavy equipment.
The following outline is provided as an overview of and guide to forestry:
Felling is the process of cutting down trees, an element of the task of logging. The person cutting the trees is a lumberjack. A feller buncher is a machine capable of felling a single large tree or grouping and felling several small ones simultaneously.
Underwater logging is the process of logging trees from underwater forests. When artificial reservoirs and dams are built, large areas of forest are often inundated; although the trees die, the wood is often preserved. The trees can then be felled using special underwater machinery and floated up to the surface. One such machine is the sawfish harvester. There is an ongoing debate to determine whether or not underwater logging is a sustainable practice and if it is more environmentally sustainable than traditional logging.
Heli-logging, or helicopter logging, is a method of logging that uses helicopters to remove cut trees from forests by lifting them on cables attached to a helicopter. Helicopter logging is often used in inaccessible areas of forests. Because the use of helicopters reduces the level of infrastructure required to log in a specific location, the method also helps to reduce the environmental impact of logging. It also can increase the productivity in these remote areas.
A chainsaw mill or PortaMill or Logosol sawmill is a type of sawmill incorporating a chainsaw, that is used by one or two operators to mill logs into lumber for use in furniture, construction and other uses. Although often used as a generic term, Alaskan Mill is a registered trademark of Granberg International.
Media related to Harvesters (forestry) at Wikimedia Commons
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