In the former, the operator usually rotates his left wrist and knocks the top hand guard forward with the back of his hand, re-setting it by reaching forward with his fingers to pull the top hand guard backwards. The chain brake may be activated deliberately by the operator, or automatically by the force of a kickback event. Correspondingly, it may require considerable force to reset.
CHAINSAW DEPTH GAUGE FULL
The spring-loaded action allows powerful braking under emergency conditions and can halt a chain under full power in a fraction of a second. The chain brake is principally operated by the top-hand guard being pushed forward to engage the brake, and pulled back to disengage. Kickback injuries usually occur to the head, face, neck and shoulders when a running chain is involved, such injuries are usually very serious, often disfiguring and sometimes fatal. Being struck by even a static chain may cause serious injury, but anything that can be done to mitigate the usually dreadful injuries caused by contact with a moving chain is of considerable benefit to operators. Secondly, the chainbrake can activate under kickback conditions to prevent the operator from being struck by a running chain. This would otherwise lead to uncontrolled chain movement, a major hazard in older saws. First, it can be used to secure the chain when changing position, moving between cuts or starting a cold saw, which requires a partly open throttle. Clamping force for the brake band is provided by a powerful spring. Specialist carving bars are available with small pointed noses.įront handguard, and combined chain brake leverĬhain brakes prevent movement of the saw's cutting chain by applying a steel brake band around the driven clutch drum. By simply reducing the diameter of the chain nose, the amount of chain, and thus the force generated during a kickback, may be reduced. The hooked nose of the tip protector can be used to "grab" branches for cutting, and presents no great drawback since these very small saw units are not used for cuts where the bar tip is buried.Ĭhainsaw carving often makes deliberate use of plunge cuts, and cuts on the tip of the bar. They find a useful application in pole pruners and one-handed battery-powered saws that are used for trimming, hedge laying etc. While these are effective, they hamper the saw in terms of the type and capacity of cuts it can execute, and are not widely used. Tip protectors are metal or plastic devices that fit over the bar tip and are usually fitted to small, domestic-class saws. Where the chain is moving downwards, as at the tip of the bar, the same reaction force now acts upwards and will cause a kickback upwards. All cutting produces a reaction force on the saw: normally this should be the lower edge of the bar, where the chain is travelling towards the saw and the reaction tends to pull the saw safely towards the log, against the spur dogs. Some saws, usually electric saws intended for domestic garden use, shield this whole area from contact with a "tip protector".
Kickback is primarily caused by cutting with the chain in the "kickback zone" on the bar, the upper quarter of the nose. Most older saws have few or none of these features, and extra care should be taken in their use.Ĭhainsaw bars Kickback reduction In addition to the safety features built into the chainsaw, operators should also wear specific chainsaw safety clothing. Most chainsaw safety features are focused on the kickback problem, and seek to either avoid it ( chain and bar design), or to reduce the risk of injury should it occur ( chain brakes). Companies continue to develop new features over time. Best practice dictates that an operator should inspect the saw before starting work and only operate the saw if all the safety features are properly functional.Īdditional safety features are a significant commercial advantage to chainsaw producers. Some features have become de facto standards, and others are legal requirements in particular jurisdictions. Manufacturers have invented numerous design features to improve safety. This article is about risk control methods specific to chainsaws and chainsaw operations.Ĭhainsaws incorporate numerous safety features common to many engine-driven power tools.
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