A tree chipper or woodchipper
Tree chippers are typically made of a hopper with a collar, the chipper mechanism itself, and an optional collection bin for the chips.
Most woodchippers rely on energy stored in a heavy flywheel to do their work (although some use drums). The chipping blades are mounted on the face of the flywheel, and the flywheel is accelerated by an electric motor or internal combustion engine.
Large woodchippers are frequently equipped with grooved rollers in the throats of their feed funnels. Once a branch has been gripped by the rollers, the rollers transport the branch to the chipping blades at a steady rate. These rollers are a safety feature and are generally reversible for situations where a branch gets caught on clothing.
File:Chipper-shredder.jpg|alt=chipper shredder|A Yardbeast 2090, showing a chipper shredder configuration. It is distinguished by two dedicated feed hoppers, for chipping and shredding. This type of machine uses a disk rotor with one or more blades and a cluster of hammers and flails to reduce the size of the material.
Image:Europe Chippers 1.jpg|This type of machine is used to chip large pieces of wood.
Image:Tree shredder 14m07.JPG|A portable woodchipper and truck with wood chips collected in the truck bed.
Image:Wood Chippings.jpg|Wood chips from a small garden chipper.
File:Forestry Chipper.jpg|Tree chipper mounted by side to tree processing into biofuel
History
The woodchipper was invented by Peter Jensen (Maasbüll, Germany) in 1884; the "Marke Angeln" soon became the core business of his company, which already produced and repaired communal- and
woodworking-
machinery.
Types
Disc
The original chipper design
employs a steel disk with blades mounted upon it as the chipping mechanism. This technology dates back to an invention by German Heinrich Wigger, for which he obtained a patent in 1922.
In this design, (usually) reversible hydraulically powered wheels draw the material from the hopper towards the disk, which is mounted perpendicularly to the incoming material. As the disk is turned by a motor, the blades mounted on the face of the disk cut the material into chips. These are thrown out the chute by flanges on the edges of the disk.
Commercial-grade disk-style chippers usually have a material diameter capacity of . Industrial-grade chippers (tub grinders) are available with discs as large as in diameter, requiring . One application of industrial disk chippers is to produce the wood chips used in the manufacture of particle board.
Drum
Drum chippers
employ mechanisms consisting of a large steel drum powered by a motor. The drum is mounted parallel to the hopper and spins toward the chute. Blades mounted to the outer surface of the drum cut the material into chips and propel the chips into the discharge chute. Commercial-grade drum-style chippers usually have a material diameter capacity of .
Conventionally-fed drum chippers use the drum as the feed mechanism, drawing the material through as it chips it. These are colloquially known as "chuck-and-duck" chippers, due to the immediate speed attained by material dropped into the drum. Chippers of this type have many drawbacks and safety issues. If an operator becomes snagged on material being fed into the machine, injury or death is very likely. Hydraulically-fed drum chippers have largely replaced conventionally-fed machines. These chippers use a set of hydraulically powered wheels to regulate the rate of feed of material into the chipper drum.
Other
Much larger machines for
wood processing exist. "Whole-tree chippers" and "recyclers", which can typically handle material diameters of , may employ drums, disks, or a combination of both. The largest machines used in wood processing, often called "tub or horizontal grinders", may handle a material diameter of or greater, and use carbide-tipped flail hammers to pulverize wood rather than cut it, producing a shredded wood rather than chip or chunk. These machines usually have a power of . Most are so heavy that they require a semi-trailer truck to be transported. Smaller models can be towed by a medium-duty truck.
Blades
Although chippers vary greatly in size, type, and capacity, the blades processing the wood are similar in construction. They are rectangular in shape and are usually across by long. They vary in thickness from about . Chipper blades are made from high-grade
steel and usually contain a minimum of 8%
chromium for hardness.
City services
Fallen branches, especially when it is suspected that they are infested by beetles or their larva, are
chipped to prevent further infestation.
[ City governments acquire and operate chippers as needed,]
Safety
Thirty-one people were killed in woodchipper accidents between 1992 and 2002 in the US, according to a 2005 report by the Journal of the American Medical Association.
In popular culture
Coen brothers's film Fargo features an infamous scene in which Peter Stormare, as Gaear Grimsrud, feeds the remains of Steve Buscemi's character, Carl Showalter, into a woodchipper.
It was claimed that Saddam Hussein used chippers to murder dissident citizens of his country,
Horror films Tucker and Dale vs. Evil (2011) and (2023) contain scenes depicting the use of a woodchipper as a murder weapon.
See also
External links
