Chainsaw
A chainsaw (also spelled chain saw) is a portable mechanical, motorized saw. It is most commonly used in forestry and by tree surgeons, to fell trees and to remove branches and foliage.Chainsaws consist of a small two-stroke gasoline (petrol) internal combustion engine (although smaller versions sometimes use electric motors), the "blade" (essentially a long metal frame) and the cutting chain itself. Each segment in this chain (which is constructed from riveted metal sections, much like a bicycle chain) features a small sharp blade. The motor drives the chain around the track at a high speed, providing an effective (if rather rough) cutting action.
Since their introduction, chainsaws have become a mainstay of forestry. Despite safety improvements, chainsaws can be dangerous, and injuries can arise from their use. The most common accident arises from "kickback", when the saw blade stalls (due either to being bound by the wood or by striking a resilient object) which causes the entire saw to jerk uncontrollably. Kickback can result in serious injuries or death. The risks associated with chainsaw use mean that protective clothing is generally worn while operating them, and many jurisdictions require that operators be certified or licensed to work with chainsaws.
The chainsaw has gained notoriety as an instrument of murder or torture, particularly in movies such as Scarface and The Texas Chainsaw Massacre and video games including DOOM and . Chainsaws are ungainly weapons and are thus used only very rarely, their only recommending factor being the terror they inspire.