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Farm Tractor Harvesting Systems
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Farm tractor harvesting operations are usually developed by farmers looking for extra income in winter months. However, a few small contractors also use them very effectively. Most people starting up an operation already have a tractor, but there are modifications that need to be made to the tractor before it can be used in harvesting operations. The ideal tractor is 60 horsepower or more with a low center of gravity. The tractor having four-wheel drive is also an added bonus. The tractor should be forestry-modified to operate safely. This typically includes a strengthened frame and three-point hitch, as well cab that is approved for protection against falling objects.
Being a lower production system, trees are typically felled and bucked (cutting the trees into logs of the desired length) with a chainsaw. Trees can also be felled and bucked with a harvesting head attachment for the three-point-hitch on the tractor.
Harvesting head mounted on an agricultural tractor
( http://www.hud-son.com/dealers.html )
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Next, the logs are extracted from the timber stand. There are several methods to accomplish this. The most common method is a skidding winch attachment on the farm tractor (also referred to as a skid plate). The skid plate is cheaper than other options, and it also allows for harvesting on steeper slopes because the tractor does not have to be driven to the stump area during removal of the log.
Agricultural Tractor with a skid plate
(from http://www.hud-son.com/dealers.html)
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Another method involves a grapple . The grapple is best suited for level ground because of the need to drive to each log during extraction.
Small grapple attachment for the three-point hitch
(from http://www.hud-son.com/dealers.html)
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The last method of extraction is the forest trailer and log loader (also referred to as a forwarding trailer). This trailer can load the logs in the timber stand. After the logs have been removed from the stand the trailer can be hooked to a truck for hauling to a mill.
Forest trailer with a log loader
(from http://www.hud-son.com/dealers.html)
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The last step is loading the logs. Most farm tractor operations will not have a forest trailer and loader on site, so the logs are loaded by other means. Almost all farm tractor loggers contract with area mills to have their logs hauled to the mill. The logger simply places the logs near a roadside, and the mill comes with self-loading trucks to picks up the logs.
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Operating Range and Conditions
Farm tractor systems are generally best suited for level to moderately-sloping terrain. They do not work well in extremely wet or swampy conditions. Skidding distances should be 500 feet or less for the system to be profitable. Farm tractors are smaller and lighter than conventional harvesting equipment, which reduces the chance of soil disturbance and residual stand damage, but also reduces handling efficiency. Loaded farm tractors can be difficult to manage with a heavy load, making these systems better suited for operations that involve small to intermediate size trees such as thinnings. Operating payloads average approximately 0.6 cords (48 ft 3 of solid wood) per turn, generating an average of 1.3 cords per hour.
Advantages
The system has four primary advantages. First, it is relatively inexpensive to establish. Second, it is a very versatile system that can effectively execute forest management regimes such as silvicultural clear-cuts, thinnings, group selection harvesting, and single-tree selection harvesting. Third, farm tractors can be adapted to a variety of tasks including cable logging (for steep terrain), cable skidding, and forwarding. Finally, soil compaction and damage to residual timber can be minimized, due to the light weight and small size of most farm tractors.
Disadvantages
Disadvantages of this system include low productivity (relative to conventional systems), early equipment failures, limited range, and elevated safety risks. Farm tractors are not designed as logging machines; they are neither as powerful nor as durable as conventional logging machines, which results in smaller payloads and more frequent breakdowns. Their lighter frame, while reducing soil compaction, can make handling difficult when hauling a load.
System Variations
Forestry equipment manufacturers currently offer a plethora of technologies that allow operators to match their farm tractor system to a wide variety of conditions. Skid distances can be extended by operating the tractor as a forwarder, rather than simply skidding the logs with a winch. For example, the challenges of steep terrain harvesting can be overcome with a three-point-hitch-mounted cable logging tower.
Koller K-300 yarder driver from the PTO of an ag tractor
(Visser and Stampfer, 1998)
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Productivity and safety can be increased with a hydraulic shear mounted on a skid-steer loader , which can dramatically reduce the need for slow and dangerous motor-manual tree felling.
Skid steer with small shear head for felling
(http://www.treeshears.com/timberwolf/default.htm )
Written by: Eric Carbaugh and Andrew Hensley
Edited by: Rien Visser
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Folkema, M.P. (1986, September). Logging Winches for Farm Tractors. Woodlot Technology, TN-90.
Folkema, M.P. (1986, September). Logging Winches for Farm Tractors. Woodlot Technology, TN-90.
Farm Tractor Logging for Woodlot Owners (1998). Retrieved March 2, 2005, from http://www.ext.vt.edu/pubs/forestry/420-090/420-090.html
Advantages and Limitations of Small-Scale Logging Technologies (2002). Ontario
Woodlot Association . Retrieved March 2, 2005, from http://www.ont-woodlot-a ssoc.org/sw_smallscalelogging.html
Huyler, N.K. and Ledoux, C.B. (1989, August), Small Tractors for Harvesting Fuelwood in Low-Volume Small-Diameter Hardwood Stands, Forest Engineering Meeting, Coeur ‘D Alene, ID.
Visser R. and K. Stampfer. 1998. Small and Medium-Scale Cable Hauler Equipment (1998). Liro Forestry Solution Reports. Retrieved March 2, 2005, from http://www.cnr.vt.edu/visser/cable_logging/europeandevelopments.htm
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