The Main Parts of a Chainsaw

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Whether you own a chainsaw or you’re planning to get one, one thing you should know about these complex machines is that they’re useful in a variety of ways. Long before the discovery of the chainsaw, people used axes to cut down trees, which, of course, was tiring as compared to the convenience offered by the chainsaw. Sadly, even after being a common machine among most farmers and timber yard owners, most people are totally ignorant about learning the various parts of a chainsaw.

Now, according to numerous studies conducted by the Centers for Disease Control and Prevention- CDC, nearly 36,000 chainsaw related injuries are recorded annually. This is because most people who buy new chainsaws don’t really know how to use them. So, to help you understand how to use a chainsaw, this guide will first discuss the various parts of a chainsaw alongside their functions. Remember, a chainsaw is a complex machine that has multiple parts. Some of these parts are designed to aid in efficiency while others are there to protect you when using the machine. In that regard, let’s now begin.

 

But First, Why Should You Know The Various Parts?

Before we get to the main party, we would like to discuss just a bit, as to why it’s important to know the various parts of a chainsaw. The first reason is your safety. You see, a chainsaw isn’t a toy but rather a complex machine that can prove deadly if not handled correctly.  Due to this reason alone, certain parts of a chainsaw must meet certain requirements as stipulated by the Occupational Safety and Health Administration (OSHA).

Additionally, most chainsaws produced after 1995 must also meet ANSI B175.1-1991 (Gasoline-Powered Chainsaws Safety Requirements).

Another reason why it’s essential to learn the various parts of a chainsaw is for maintenance purposes. Just to be realistic, it will be impossible to maintain your chainsaw if you hardly know its various parts and how they work. Therefore, having a basic understanding of your chainsaw will help you to maintain it, which in turn will reduce repair costs.

Finally, there’s the issue of communication. Now, imagine you wish to replace a faulty component in your chainsaw. How would you make an order when you hardly know the name of the specific component and what it’s tasked to do?

Now that you have a reason why you need to know about the different parts of a chainsaw, this guide will get straight to the point. Since we will mention both primary and secondary parts, the most important parts (primary) that must meet OSHA’s requirements will be identified by a mark (*).

 

Parts of a Chainsaw: Their Functions

 

1. *The Chain Catcher

The first part of a chainsaw, which happens to be an OSHA requirement, is the chain catcher. This is generally a plastic or metallic guard that’s intended to protect the operator from any injuries in case the chain breaks during operation.  You see, when the chain is spinning at a rapid pace, there are chances that it might break or come off the bar causing it to smash against the operator. Thankfully, with a chain catcher, the chain can easily be trapped to prevent it from causing any damage. Due to this huge task, the chain catcher can sometimes wear out forcing you to replace it regularly.

 

2. *Throttle

Just like your car’s gas pedal, the throttle is what triggers the speed of the chain when operating. Located on the underside of the rear handle, the throttle is tasked to regulate the RPM by either increasing or decreasing the amount of fuel getting to the combustion chamber. The more the available fuel, the better it is for the engine to function.

In the case of an electric chainsaw, the throttle controls the amount of amperage getting to the motor resulting in a faster and more efficient chainsaw. But, for the throttle to work, you need to engage the throttle lockout.

 

3. *Throttle Lock

Also known as the safety throttle, the throttle interlock, and the throttle trigger lock, this safety lock is specifically intended to prevent the chainsaw from being triggered accidentally. While the throttle is located underneath the rear handle, the throttle trigger lock sits on top of the rear handle making it easy to press. Since a chainsaw is a dangerous machine, the throttle lock ensures that the chainsaw cannot be activated when it’s in the idle position. Due to its huge importance, the throttle lock is another OSHA requirement that must be present in any chainsaw.

 

4. Chain

Although it’s not an OSHA requirement, the chain is the most important component of the chainsaw without which the chainsaw cannot operate. It’s that part of the chainsaw that does the actual cutting. Now, for effective cutting to take place, the chain has several parts that work simultaneously. These parts include the left and right cutter teeth, the drive links, tie strap, and the rakers.

Now, the cutter teeth are self-explanatory as they’re tasked to do the cutting. The tie straps, on the other hand, are the ones that connect the drive links to the cutter teeth. Once connected, the drive links merge the chain to the bar and ensure the chain is perfectly propelled by the motor. To make the chainsaw more manageable while reducing chances of kickback, the cutter teeth must be sharpened regularly.

 

5. Guide Bar

Another part of a chainsaw you should be aware of is the guide bar. If you’re new to chainsaws, you can easily confuse the chain and the guide bar quite easily. While the chain is tasked to do the actual cutting, the guide bar is the tough steel alloy bar that holds the chain in position.

In addition to holding the chain, the bar is responsible for determining the actual length of the chainsaw. With its size varying anywhere from 16” to 24” and above, the bar also determines the furthest you can reach when cutting a tree and whether you’ll need to rotate around the tree when cutting.

 

6. *Hand Guard

Another convenient part of your chainsaw, which by the way is an OSHA requirement, is the handguard. You see, during the cutting process, pieces of debris are left flying on the air due to the speeding chain. There are also cases of kickback especially when the cutter teeth are not sharpened properly. So, to protect you from any of these scenarios, which can cause potential injuries, the handguard must be present to guarantee you a comfortable grip. This part usually runs from the base to the top of the motor.

 

7. *Chain Brake

Located just above the guide bar and the engine, there’s the chain brake. This part of the chainsaw is among the most important safety features that are both OSHA and ANSI B175.1-1991 safety requirements. Most of the time, when you’re cutting using the nose/tip of the chain, the chain can sometimes get pinched by the wood causing it to shoot upwards resulting in a kickback.

This kickback motion usually targets the upper parts of your body such as the head, shoulders, neck, and face, and can cause major hazards and even death. Therefore, to mitigate these dreadful injuries, a chain brake becomes a necessity that must be present on any chainsaw.

To operate the brake, an operator only needs to push the hand guard-forward. From there, a steel brake band powered by a powerful spring is tied around the driven clutch drum to stop the chain from rotating. Following the advancement in technology, the chain brake can either be manual (activated deliberately by the operator) or automatic (activated by inertia or the kickback force).

 

8. Engine

Another essential part of your chainsaw is the engine. Usually protected under a metal block, the engine lies behind the spark plug and it comprises of a motor that’s connected to the cutting chain via the clutch. Most chainsaw engines are internal combustion meaning they rely on gasoline to operate. However, following recent technological improvements, electric and battery-powered chainsaws are slowly taking the main stage thanks to their environmentally friendly characteristics.

 

9. Clutch

Another part of the chainsaw that lies next to the engine is the clutch. This piece of a thin metal ring is designed to accomplish several specific tasks. The first task of the clutch is to work closely with the brakes. You see, when an operator applies the brakes, the braking system activates the clutch. For the chain to stop, the clutch squeezes against the sprocket to stop the motion.

In case you didn’t know, the sprocket is a cylindrical drum that houses the clutch and small teeth that hold the chain when it’s spinning. Now, the second task of the clutch is to prevent your chainsaw’s chain from rotating when the engine is idling. This is an important safety feature that protects an operator from any accidents caused by human error.

The last and most important task of a clutch is to protect the engine from stalling in case the chain stops abruptly. This is one feature that ensures your chainsaw’s engine is running consistently and efficiently.

 

10. Flywheel

The flywheel is another crucial part of the chainsaw that’s located inside the engine. This component has two major roles. The first role is to store kinetic energy in the form of rotational energy to be used in regulating the speed and momentum of the engine when rotating the chain. This mechanism ensures a safe, smooth, and efficient working of the engine.

If you look at a flywheel closely, you’ll notice that it resembles a fan. This unique design allows the flywheel to accomplish its second task that is cooling down the engine/motor to prevent overheating. Since the flywheel rotates at a rapid pace, its edges can easily bend, break, or get clogged. Due to these reasons, it’s highly recommended that you keep a close eye on this component to avoid damaging the engine.

 

11. Filters

In this section, we will discuss both the air and fuel filters. That’s because both of these parts perform an identical role of preventing impurities from getting inside the carburetor. Now, about the air filter, this one is concealed under the air filter cover. Its main purpose is to purify the air getting into the carburetor ensuring that it doesn’t have any impurities such as sawdust, normal dust, and small wooden chunks.

The fuel filter on its part is tasked with ensuring that the fuel entering into the carburetor is purified from dust, sawdust, and other small particles. With clean fuel and air, there’s an efficient fuel-air mixture that produces enough energy to power the chainsaw’s engine.

 

12. Carburetor

The carburetor is another crucial part of the chainsaw that controls the amount of fuel intake into the engine. Unlike a car’s carburetor, a chainsaw carburetor is pretty simple as it doesn’t have a lot of complex parts. Its main task comes in when you’re trying to start the chainsaw when the engine is cold, idling or when it’s running.

Now, a carburetor comprises of a throttle plate that controls the amount of air getting in from the air filter. It also has a narrow tube called a venture. Inside the venture, there’s another narrow hole called a jet. During operation, air flowing through the throttle plate creates a vacuum in the venture, which in return attracts a metered amount of fuel via the jets to support combustion.

 

13. *Muffler

Another OSHA requirement in a chainsaw is the muffler. Just like in an automotive, the muffler serves the same purpose of absorbing the noise to make the chainsaw bearable to the operator without damaging his/her ears. In addition to that, the muffler does a crucial task of pushing exhaust fumes away from the operator thus reducing the amount of fumes a chainsaw operator inhales. In most chainsaws, especially the Stihl chainsaw, the muffler can easily be removed for maintenance purposes.

 

14. Spark Plug

Just like in an automotive, the purpose of the spark plug in a gas chainsaw is to create the spark that ignites the fuel-air mixture. Since a chainsaw is designed to accomplish many difficult chores, it’s good to keep a closer eye on the spark plug through regular maintenance to ensure that it works at its best.

 

15. Spark Arrestor

We’ve already discussed the purpose of the muffler. Now, during operation, the muffler can sometimes release hot sparks and tiny projectiles (small pieces of metal) which can either cause a fire hazard or fly out of the chainsaw onto the operator’s face. So, to prevent such unenforceable accidents, a thin mesh-like screen is added inside the muffler to arrest these sparks.

 

16. Tensioners

The tensioner is another equally important part of your chainsaw. Located on the side of the chainsaw, the tensioner is generally a screw that’s tasked to loosen or tighten the chain. To access the tension screw, you have to loosen the clutch cover nuts first before turning it clockwise or anticlockwise. By doing this, you generally minimize the rapid wear of the chain as well as your safety in case the chain breaks during operation.

 

17. *Anti-Vibration System

When a chainsaw is cutting, the engine is likely to cause vibrations that can turn to be sensitive to your hands. In fact, excess vibrations for a long time can expose an operator to severe hand-arm vibration syndrome (HAVS). These vibrations can also put a lot of stress on your arms and joints making it difficult to handle a chainsaw when cutting.

Now, a chainsaw is divided into two parts. The first consists of the chain cutter and the engine while the other part consists of the handles and the controls. In between these two rigid assemblies, there’s the anti-vibration system that comes in the form of a spring suspension. This suspension system consists of metal springs and rubber bushes that work together to absorb the vibrations caused by the engine and the chain cutter.

 

18. Manual Fuel Pump

The manual fuel pump is a smart feature that’s available in most chainsaws and power tools in general. It comprises of a ball like a primer bulb which when pressed fills the chamber of the carburetor with fuel. This technique creates enough fuel-air mixture that gives the engine a head start to ignite. With this feature, you’ll generally need a few pulls on the pull cord to start the engine.

 

19. Decompression Valve

Although this is not a standard part found in all chainsaws, it plays a key role in easing pressure from the pistons to make it easier to start the engine using the recoil start handle. Just like the manual fuel pump, the decompression valve is a small button that you press manually using your finger.

Now, depending on the chainsaw model you’re using, the decompressor valve can either be manual or automatic. However though, whether it’s manually activated or self-activated, this valve usually opens when you’re starting the engine and immediately shuts down once the engine starts.

 

20. On/Off Switch

Just like in most cases, the on/off switch is used to turn the engine on or off by blocking the ignition coil from firing. Also called a kill switch, this part of the chainsaw is responsible for shutting down the engine once you’re done using the chainsaw.

 

21. High/Low Adjustment

The high and low adjustment screws are usually marked with initials (H) and (L). Although they’re usually factory-set, sometimes it becomes necessary to adjust them especially after cleaning the carburetor to ensure optimal performance. Their main purpose, however, is to regulate the amount of fuel-air mixture to control the engine’s RPM.

 

22. Pull Cord

This is typically a small rope with a plastic handle. Its purpose is to start the engine. The pull cord is not a newcomer but rather a familiar technique of starting most appliances that rely on the internal combustion engine. They include lawnmowers, weed eaters, pumps, chainsaws outboard motors, and small aircraft among others.

 

23. Fuel Tank

The fuel tank isn’t something new to most people. This is where you put the gas or fuel in the chainsaw. Now, the fuel tank is usually part of the fuel supply system with the rest being the filters, the fuel pump, the valves, connecting pipes, and the heat exchanger. The gas tank stores the fuel until it’s needed to power the engine. Upon request, the fuel is pumped to the filters where it’s purified before being transported by the connecting pipes to the fuel injector (s).

 

24. Lubricant Tank

Just like the fuel tank, the lubricant tank provides a way of adding oil to the chainsaw. You see, when you’re running a chainsaw, there’s usually a constant metal-to-metal contact between the bar and the chain. This contact can produce serious friction that can damage the chain or the chainsaw. Therefore, to reduce this friction as well as the heat generated, a lubricant is an absolute must.

 

Conclusion

As you can see, a chainsaw is generally a convergence of multiple parts that work behind the scenes to accomplish the various cutting tasks. As I mentioned earlier, the most crucial parts that are OSHA requirements are marked with an asterisk (*). Although we haven’t mentioned everything, at least we’ve listed the basic parts that keep the chainsaw up and running.

Another thing about these parts is that they aren’t 100% accurate. That’s because chainsaws come in different flavors and varieties some of which are way different from the others. Thankfully, this guide is more of an eye-opener that will teach you the basics as you expand your knowledge.