A chainsaw (or chain saw) is a portable mechanical, motorized saw. It is used in logging activities such as felling, limbing, and bucking; by tree surgeons to fell trees and remove branches and foliage; to fell snags and assist in cutting firebreaks in wildland fire suppression, and to harvest firewood. Chainsaws with specially designed blades have been developed as tools for use in chainsaw art.
A chainsaw consists of a several parts.
The underside of each link features a small metal finger that keeps the tooth centered between the rails of the bar, helps to carry lubricating oil around the bar, and engages with the engine's drive sprocket inside the body of the saw. The engine drives the chain around the track by a centrifugal clutch, engaging the chain at high speed but running free at lower speed. The chain on the lower side of the cutter bar is normally used for cutting, working towards the operator.
As chainsaws become more popular among home owners, chainsaw manufacturers are introducing features to make them easier to use.
As chainsaw carving has become more popular, chainsaw manufacturers are making special short, narrow-tipped bars for carving. These are called "quarter tipped," "nickel tipped" or "dime tipped" bars, based on the size of the round tip. Echo sponsors a carving series, as well as carvers such as former Runaways singer Cherie Currie. RedMax specifically built the G3200 CV chainsaw for carving applications.
Most chainsaws require two sources of lubrication. Like most two-stroke engines, the engine is lubricated by its fuel, which contains about 2 – 5% (depending on model) oil dissolved in the fuel. Separate chain oil is used for the external lubrication of the bar and chain. The chain oil is depleted quickly because it tends to be thrown off the chain by centrifugal force, and it is soaked up by sawdust. The chain oil reservoir is usually topped up at the same time as refuelling, and the reservoir is large enough so that the saw runs out of fuel and stops before the chain oil runs dry. Failing to keep the chain oil topped up, or using an oil of incorrect viscosity, is a common source of damage to saws, and tends to lead to rapid wear of the bar, or the chain jamming or coming off the bar.
Chains must be kept very sharp to perform well, and become blunt very rapidly if they touch soil, metal or stones. When blunt, they tend to produce powdery sawdust, rather than the longer, clean shavings characteristic of a sharp chain; a sharp saw also needs very little force from the operator to push it into the cut. Special hardened chains (made with tungsten carbide) are used for applications where soil is likely to contaminate the cut, such as for cutting through roots.
The air intake filter tends to clog up with sawdust. This must be cleaned from time to time, but is not a problem during normal operation.
Despite safety features and protective clothing, injuries can still arise from chainsaw use, from the large forces involved in the work, from the fast-moving, sharp chain, or from the vibration and noise of the machinery.
The most common accident arises from kickback, when a chain tooth at the tip of the guide bar catches on wood without cutting through it. This throws the bar (with its moving chain) in an upward arc toward the operator, often causing serious injury or even death.
Another dangerous situation occurs when heavy timber begins to fall or shift before a cut is complete – the chainsaw operator may be trapped or crushed. Similarly, timber falling in an unplanned direction may harm the operator or other workers, or an operator working at a height may fall or be injured by falling timber.
Like other hand-held machinery, the operation of chainsaws can cause vibration white finger, tinnitus or industrial deafness.
The risks associated with chainsaw use mean that protective clothing and hearing protectors are normally worn while operating them, and many jurisdictions require that operators be certified or licensed to work with chainsaws. Injury can also result if the chain breaks during operation due to poor maintenance or attempting to cut inappropriate materials.
Two important contributors to the modern chainsaw are Joseph Buford Cox and Andreas Stihl; the latter patented and developed a chainsaw in 1926 and a gasoline-powered chainsaw in 1929, and founded a company to mass-produce them. In 1927, Emil Lerp, the founder of Dolmar, developed the world's first gasoline-powered chainsaw and mass-produced them. McCulloch and Industrial Equipment Corp in North America started to produce chainsaws. The early models were heavy, two-person devices with long bars. Often chainsaws were so heavy that they had wheels like dragsaws. Other outfits used driven lines from a wheeled power unit to drive the cutting bar.
After World War II, improvements in aluminum and engine design lightened chainsaws to the point where one person could carry them. In some areas the skidder / chainsaw crews have been largely replaced by the feller buncher and harvester.
Chainsaws have almost entirely replaced simple man-powered saws in forestry. They come in many sizes, from small electric saws intended for home and garden use, to large "lumberjack" saws. Members of military engineer units are trained to use chainsaws.
In films and computer games, the chainsaw is usually used as a weapon or an instrument of murder or torture, most famously in The Texas Chain Saw Massacre and its sequels, as well as many subsequent films (such as Scarface, Deliria, and Halloween: Resurrection).
The chainsaw is also synonymous with zombie related movies and games, as seen in Dawn of the Deadand Night of the Living Dead, The chainsaw has also been used as a musical instrument by musicians such as Jesse Dupree of the American rock band, Jackyl, Finnish punk rocker Maukka Perusjätkä and Swedish ensemble Peter Carlsson & Blå Grodorna.
In The Simpsons Movie, Homer Simpson tries to defend his family by "faking" a chainsaw motor, but failed.
|
|
|
|
|
|
|
|
|
|
|