Safety Tailgate
Chainsaw Rotational Kickback Even the most experienced user is susceptible to this machine’s dangerous kick By Kevin Myers, Arborist training instructor ACRT Arborist Training
For many arborists, a chainsaw is an everyday tool. With such regular, fre- quent use, it can be easy to slip into complacency. Knowing and under- standing chainsaw kickback can help prevent incidents or injuries. No matter how long you’ve been in the industry, remembering and following safety best-management practices in your day-to-day work can be one of the most important things you accomplish every day. For many who are involved in this industry, there’s an inherent el- ement of risk. But we can mitigate that risk by staying on top of established safety guidelines. For those who regularly work with chainsaws, kickback is potentially one of the most dangerous and devastat- ing safety hazards we may encounter. The sudden, unexpected, and forceful movement – kick – of an operating chainsaw can cause serious injury to an unprepared operator. And it can happen to even the most skilled chain- saw user. None of this is new. Kickback is widely understood, and just about every regu- lar chainsaw user is aware of it. So why do incidents continue to occur? What can we be doing to prevent kickback incidents? It starts with an understanding of kickback and what causes it to occur. It ends with always remaining vigilant when it comes to safe chainsaw opera- tion and maintenance.
Rotational kickback can occur when a chainsaw's rotation stops suddenly, causing the machine to bounce backwards toward the operator.
That sudden, split-second halt is usually caused by a cutter tooth of the chain being exposed to a larger bite of wood as it passes the upper quad- rant of the guide bar’s tip, or when it comes in contact with a foreign object. Why does this happen? Under ordi- nary circumstances, the saw chain very quickly shaves many thin strips of wood out of a cut. Think of a bench planer, if you’re familiar, which is gen- erally used to remove a thin top layer of a piece of wood; a saw chain operates similarly, but far more rapidly. Those thin cuts are critical here. The depth of each cut made by the saw chain is determined by the raker or depth gauge. The raker passes across the top of the existing cut, or wood sur- face, and determines the thickness of the material being shaved off by the
UNDERSTANDING KICKBACK Any chainsaw is a powerful piece of equipment. No matter the size of the individual saw, significant force and power keep the cutting chain rotat- ing at high speeds to efficiently cut through wood. Throughout the operation, the force that keeps the chain moving is acting just the same on the body of the saw as it is on the chain itself. With an operator holding the body of the saw steady, the force causes the chain to rotate as intended. But when the chain’s rotation is sudden- ly halted, all that force has to go some- where, and the momentum is trans- ferred, forcing the saw to pivot up and back toward the operator. This is com- monly known as a rotational kickback.
50 | ArborTIMES Winter 2024
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