Over the years I have listened to my dad and grandpa discuss “days gone by” and the changes that have taken place during the course of their lives. I am often amazed at the wonderful new advancements that did not exit during their lives, and of which I have often taken for granted. Of the many advancements in safety and protection that I could write about, the modern chainsaw and associated personal protective equipment is noteworthy to a person who lives in a part of the country where long cold winters are a norm, where a fireplace is a treasured convenience, and where the annual harvesting of wood for are a part of life. While I or any of my family members have never suffered personal injury from using a chainsaw, I know those that have and feel anguish for them and what they are enduring as a result of their injuries.
Unlike those my grandfather and father used, the modern chainsaw comes with safety features designed to protect the user form severe lacerations, the number one injury to chainsaw users. Most lacerations come form an event known as kickback, the sudden, forceful, and unexpected upward kick of the chainsaw’s guide bar with spinning chain and teeth. Kickback can occur when a saw tooth on the top part of the tip of the guide bar (known as the kickback zone) “catches” on a part of the wood you are cutting, such as a knot in the wood, or even “pinched” between the cut part of the log. The powerful rotational spin of the chain moving downward produces a reaction force causing the saw to violently kick backwards towards the user with the potential for serious injury. Most injuries are to the head, face, neck, and shoulder area.
Conversely, if cutting with the lower edge of the guide bar as directed for proper technique, with the chain traveling towards the saw, the reaction force tends to pull the saw into the log. This proper cutting technique, while not a chainsaw safety feature, is probably the most important technique of proper chainsaw use.
Key safety features of the modern chainsaw include:
- Tip Protectors: Some smaller, usually yard and garden use electric chainsaws, have tip protectors fitted to the kickback zone area of the chainsaw guide bar. The tip protectors prevent the “catching” of the saw’s teeth in the kickback zone and have proven effective in reducing kickback.
- Chain: There are suitable chains to use with specific model chainsaws. The chainsaw manufacture will usually specify this in the product’s informational materials. On the chain there are small steel protruding depth gauges positioned in front of each cutting tooth. The height of the depth gauge determines the depth of cut the tooth will make as it passes through the wood. It should be an appropriate height to allow for sufficient cut depth, but if the difference between the tooth cutting edge and depth gauge is too great the saw will cut too deeply and result in a more difficult to control chainsaw and increased risk for kickback.
Some chainsaw models have chains that are engineered with a reduced nose radius to yield a reduced kickback force should it occur. This safety feature can slightly reduce the chain’s cutting capacity.
- Kickback Guard and Chain Brake: The kickback guard (or hand guard) is located in front of the front handle, where the user grasps the chainsaw with his/her lead hand. The chain brake, when activated, will immediately stop the movement of the chain in a fraction of a second. This safety feature is used or activated to fulfill important purposes. First, if manually and purposely activated, it stops the chain when desired for repositioning and moving between cuts, times of risk for mishap. Second, the chain brake will be automatically activated if the kickback/hand guard is pushed forward as would occur during a kickback event as the user’s hand would automatically be in a position of opposition to the backward kick of the saw. The chain brake will stay activated until the kickback/hand guard is pulled back to disengage.
Certain chainsaw manufactures have developed an “inertia” activated chain brake system that will engage the chain brake if the guide bar is violently thrust upwards in a kickback motion.
- Wrap-Around Front Handle: This feature allows the chainsaw operator to hold the saw on the left side of the saw and make horizontal (right to left) cuts. This then removes the operators head, face, neck, and shoulder area form the plane of the chainsaw cut so that if a kickback event were to occur, these body parts are not in the line of the cutting plane.
- Chain Catcher: The chain catcher is a uniquely designed protruding structure that if the chain breaks or becomes derailed form the guide bar, the catcher will snag it, effectively shortening the amount of chain that continues to move around and underneath the saw body to ultimately smash against the bottom portion of the rear hand grip. For this purpose, the bottom portion is wider than the top portion offering a greater surface area for protection from the whipped broken chain to smash into.
- Throttle Lock: The engine throttle is operated by the operator’s index (or trigger finger) and is located under the rear handle of the saw. The throttle lock is located on top of the rear handle of the saw. The throttle will not work unless the throttle lock is simultaneously depressed as would be the case when firmly holding on to the rear handle and also pressing on the trigger. This safety feature prevents the chain from being activated inadvertently as might be the case if the engine trigger throttle was hit by a branch of object. Some models may engineer the chain brake to be engaged if the throttle lock is disengaged, providing another safety feature.
- Stop Control or On/Off Switch: The switch itself requires a fair amount of force to move form the on to off position, and vice-versa. This is required so that the saw will not shut off due to the significant vibration forces that are working on the saw during use. If this stops the operator from completing a cut it might pose a risk of requiring work on the saw with the tree in a partially felled position.
The location of the switch must be clearly marked for identification on the saw and easily accessible should an operator sustain injury or for any reason be removed his/her proper gripping of the saw and another person need to move in and switch the saw off.
- Centrifugal Clutch: This safety feature automatically disengages the chain when the engine is in idle mode, so it does not move around the guide bar. A non-moving chain is much less likely to cause harm if accidently touched for bumped up against than a moving chain, even if it were only moving at a slow speed.
- Anti-Vibration Mechanism: Modern chainsaws come equipped with an anti-vibration mechanism. To accomplish this the chain saw is divided into two different parts (the guide bar and engine that when being operated produces powerful vibrational forces, and the handles and controls). These two parts are separated (and joined together) by either spring mounts or rubber bushings that provide an absorption of the vibrations and reduction of the forces being exerted against the operator’s hands. In a previous article “Jack Hammer Gloves – Yes or No?” we discussed the potential impact of chronic vibration leading to a condition referred as Hand-Arm Vibration Syndrome (HAVS). This condition can be serious and lead to a permeant disability that might require the discontinuation of any activity that produces vibrational forces.
In addition to all these safety features, it is strongly recommended that anyone beginning to use this powerful machine participate in a chainsaw use training program. These trainings will include helpful information on how to safely use your chainsaw, how to properly care for your chainsaw, how to safely fell a tree, and other important and helpful information to keep your safe and effective in your efforts.
Not only has the chainsaw undergone advancements in safety, but the development of improved personal protective equipment has further reduced the risk of serious injury.
Personal Protective Equipment for the Chainsaw Operator Includes:
- Safety Hard Hats & Protective Eyewear: Considering that the head and face are two of the most common areas for injury from chainsaw kickback, a safety hard hat and protective eyewear are safety essentials when working a chainsaw. The force of a hurling chunk of cut wood could cause serious damage to an eye. In addition, a hard hat is designed to help protect the head from falling objects, including the potential of a falling tree.
- Protective Gloves: The right kind and fit of gloves helps ensure a good grip for more effective handling of the machine. Gloves also project your hands and fingers from splintered wood fragments, or for protection against the potentially deleterious effects of chronic vibration in the development of Hand-Arm Vibration Syndrome (HAVS).
- Work Boots: Select boots that are solid and sturdy in their construction, provide good grip for sure footing and protection against slipping. The added benefit of a steel-toe shoe may be just what is needed for those unanticipated accidents that can result in something being dropped on or struck against your foot.
- Ear Muffs: Protect your hearing from all loud equipment, including chainsaws.
- Protective Upper Body and Lower Body Apparel: Protect all your body parts from fast flying splintered wood, those not covered by your safety hard hat and eyewear, boots and gloves, by wearing protective jackets and chaps.
The chainsaw features and personal wear that have developed over time, have advanced safety protection for all those who engage in this outdoor experience of providing wood for your fire, in caring for a yard, or even cutting down a Christmas tree. What advancements are yet to come?
[author] [author_image timthumb=’on’][/author_image] [author_info]Trevor has been with Online Safety Depot for the past year. He has experience working in both the public and private sector. He is a father to three wonderful kids who keep him busy when he is not working and a beautiful wife who is his best friend and supporter in life. He enjoys hiking, camping and fly-fishing in Yellowstone National Park and its surrounding wilderness. [/author_info] [/author]