chainsaw

A chainsaw is a portable mechanical saw that uses a rotating loop of toothed metal chain around a guide bar to cut wood. It can be powered by a two-stroke gasoline engine, a battery-powered electric motor, or a corded electric motor. Chainsaws are widely used for tree felling, bucking, limbing, pruning, and various tasks in construction, forestry, and rescue operations.

Design and variants include petrol, cordless electric, and corded electric models. The main components are the drive sprocket, guide bar, and a continuously moving cutting chain. Bar lengths vary, commonly from about 8 to 36 inches, with longer bars for larger trees and shorter bars for pruning or precision work. Chains differ in pitch, gauge, and tooth shape to balance cutting speed and durability. Petrol chainsaws typically use small two-stroke engines, while cordless models rely on lithium-ion batteries and corded models use electric motors.

Operation and maintenance involve lubrication of the chain by bar oil, proper chain tension, and regular sharpening or replacement of chain teeth. The high-speed chain presents a risk of kickback, where the bar can move suddenly toward the operator, so many models include safety features such as a chain brake, anti-kickback mechanisms, and throttle interlocks. Operators should use appropriate personal protective equipment and follow safety guidelines for handling, starting, and stopping the saw, as well as routine maintenance like cleaning air filters and inspecting the bar and chain.

History and development trace the modern chainsaw to early 20th-century innovations, with Andreas Stihl and other manufacturers producing portable models that enabled single-person operation. Since then, designs have evolved toward greater power, lighter weight, and improved safety and efficiency.