Chainsaw — portable mechanical saw: design, history, uses, and safety

Design and main components

A typical chainsaw consists of a power unit, guide bar, cutting chain, sprocket and casing. Power sources include internal combustion two-stroke engines, four-stroke engines, corded electric motors and battery-driven electric motors. Fuel- and battery-powered models differ in weight, noise and emissions. Chains have alternating cutting teeth and depth gauges; correct chain tension and lubrication are essential for safe operation. For engine types and fuel systems see powertrain types.

History and development

Early chain-driven cutting devices date back to the 19th century; a medical chain osteotome was an early example. In the early 20th century inventors and manufacturers produced progressively lighter, more reliable portable saws suitable for forestry. Improvements over decades introduced anti-vibration mounts, chain brakes, lighter materials and, more recently, electric and battery technologies that reduce emissions and maintenance.

Uses and variations

Chainsaws are used to fell trees, limb branches, cut firewood, and clear vegetation. Firefighters and wildland crews use chainsaws to create fuel breaks and firelines during wildfire suppression; specialized chainsaws and cutting systems are also employed to cut concrete or metal in construction and rescue operations. Ice carving and logging competitions are other examples of specialized use. For firefighting applications, see fireline and firebreak cutting.

Safety, maintenance and operation

• Wear personal protective equipment: helmet with face shield, eye protection, ear protection, chainsaw chaps, gloves and steel-toe boots.
• Use safety features: chain brake, throttle interlock, chain catcher and low-kickback chains when appropriate.
• Maintain the saw: keep the chain sharp, maintain correct tension, clean the air filter, and use bar oil for lubrication.
• Beware of kickback, falling trees, and projectiles; plan escape routes and never work alone in hazardous conditions.

Notable distinctions

Models differ by guide bar length, chain pitch and gauge, power source and intended application. Short-bar saws are used for pruning and rescue; long-bar saws and professional-grade machines are used for felling large trees. Electric and battery chainsaws are increasingly common for residential use because they are quieter and produce fewer emissions, while petrol models remain preferred for heavy-duty, remote work where refueling is easier than recharging.