Brush up on chainsaw safety

Photos: ACRT
Photos: ACRT
Rotational kickback is one of the biggest safety
issues surrounding chainsaw use. Photos: ACRT

Many landscape and tree care professionals use a chainsaw daily—but that doesn’t mean safe handling best practices should be taken lightly.

We all fall into routines, whether it’s how you get ready for work each day, the route you take to get there or how you perform your job.

But for those of us working with powerful equipment each day, it’s critical that we put safety first and that we don’t fall into complacency. There’s an element of risk in taking on big pruning and removal jobs, no matter the application. Allowing ourselves to shrug off simple safety measures in favor of quickness or efficiency can’t happen.

Nowhere is that more important than when handling a chainsaw. For those of us who work with chainsaws regularly, we know rotational kickback is something we need to work to avoid at all times. This is when the chainsaw suddenly and forcefully kicks back at the operator, and it can cause potentially devastating injury to both novices and the most seasoned chainsaw users.

Understanding is key to prevention. That’s why it’s worth brushing up on kickback.

What causes kickback?

Stop and think about how a chainsaw works. Dozens of sharp, heavy-duty cutter teeth race around the bar quickly enough to cleanly cut through large branches and logs. It’s a powerful instrument, and its operation depends on much force, torque and speed.

And that’s where rotational kickback starts, occurring when the chain’s rotation is suddenly halted, even for just a split second, by some interfering element. When this happens, the force that keeps the chain moving along the bar must be transferred somewhere. In a kickback event, it’s transferred to the body of the saw, forcing the entire device to pivot or “kick” backward toward the operator.

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A well-maintained machine is less likely to kickback Photos: ACRT

So, what causes kickback? Under ordinary operation, each tooth of the saw chain shaves off a little individual piece of wood. Of course, this happens very rapidly in chainsaw operation, allowing for the clean, rapid cut. The shallow depth of each individual cut is determined by the raker (or depth gauge), allowing just a small bit of wood to be cut by the tooth.

Kickback happens when a larger bit of wood or some other foreign object hits the cutting tooth. Since the device isn’t designed for such a large piece of wood, it causes the chain to stop completely for a split second, causing the transfer of rotational force that results in kickback. This is most likely to occur in the upper quadrant of the chain’s guide bar, called “the kickback zone.”

Most chainsaws are designed so the depth gauge allows approximately 0.018 inches to 0.030 inches of wood to be cut in each individual cut. In the kickback zone, the orientation of the chain is such that it allows much more wood than designed for to drop below the cutting tooth.

Kickback prevention

The basic premise of kickback prevention is simple enough: Don’t hit a piece of wood in the kickback zone during chainsaw operation.

But, as we know, field work isn’t always so uniform, and most kickback events happen due to incidental contact. While bucking a large log, a chainsaw user might unintentionally strike a branch or other log behind his or her target with the tip of the bar. Elsewhere, there are a number of advanced cutting methods, including bore cutting, that involve intentionally sticking the tip of the bar into a piece of wood or tree.

In the end, it comes down to situational awareness when you’re working with a chainsaw. Pay attention at all times to how, where and what you’re cutting. Know where the tip of the bar is, no matter what you’re doing, and always pay attention for interfering objects. Ensuring a proper grip on the saw at all times is also helpful, keeping your left hand and thumb firmly gripped around the forward handle, while the right hand and thumb are gripped around the rear handle.

Being diligent and engaged when using a chainsaw helps avoid dangerous encounters. Photos: ACRT

Locking your left arm during operation, so your elbow does not form an easy pivot point, also can help in case kickback does accidentally occur. Keeping your head positioned to the side of the bar ensures your head is clear if kickback occurs. Additionally, while operating the chainsaw, it’s imperative that you maintain proper body position and avoid cuts above your shoulders.

Equipment care and preventive maintenance

Ensuring your equipment is in proper working order is another critical component of overall safety. Most modern chainsaws have incorporated new safety devices that have made the devices less risky than ever, whether they’re homeowner saws, reduced kickback chains or chain brakes.

These things work only if the entire chainsaw is in proper working order, especially the chain brake, which can be the difference between a minor or major injury during a kickback event. The chain brake stops the movement of the saw’s cutting chain, primarily used to prevent accidental acceleration while the operator is adjusting cutting positions. In a kickback event, though, it can be used to mitigate the potential damage. Being hit by a static chain can still be harmful but will cause significantly less damage than being hit by a moving one.

Always follow manufacturer instructions when caring for this equipment, as different saws from different manufacturers vary. Most saws are equipped with two braking systems, a mechanical brake and an inertia braking system. Elsewhere, some manufacturers build in a third braking option. Consider Husqvarna’s TrioBrake, which employs a second mechanical brake at the rear of the saw and Stihl’s Quickstop Plus option where the brake engages when your right hand is removed from the rear handle of the saw.

No matter the saw you’re using, vigilance is the most important thing you can do from a safety perspective. Don’t let yourself fall into complacency during chainsaw operation.

Photos: ACRT

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Kevin Myers

Myers is an ISA-certified arborist, ISA-certified Utility Specialist, Arborist Training Instructor with ACRT and recipient of the 2016 UAA Silver Shield Award

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