Three power sources
When looking at the options for chainsaws on the market you will find many different sizes and specifications. However, they all fall into three main categories. They are either petrol powered, electric or battery operated. All three versions have their own advantages and disadvantages, but basically, the choice is dependant on the type of work you will be doing. The petrol chainsaw is more powerful and heavier than the electric model (due to the size of the engine and the fuel) whereas the electric model, although lighter, has the restrictions of the lead which need to be plugged into the energy source. For these reasons, petrol models are used for big jobs where you need to perhaps travel large distances (you should take into account that you may also be going up high as well as horizontally!). The electric chainsaws lightness and lead restrictions make it more suitable for small domestic jobs and projects. The compromise between the two is the battery operated chainsaw. This has the advantage of being cordless and being light at the same time but is considerably less powerful.
Inside a petrol chainsaw
The chainsaw is usually a two stroke engine. If you understand the mechanical makeup of engines you will immediately see a specific difference in a two stroke engine created for use within a chainsaw. You will not see the usual cams and assorted valves. The chainsaw engine is a good deal simpler. Designers have simplified the workings of the machine in an attempt to balance the power-weight ratio. The two-stroke engine can create greater power than the 4 stroke due to the increased number of rotations of the crankshaft. Despite their small size, the chainsaw motors can actually generate an enormous amount of power and the engine can rev in excess of 10,000 rpm’s.
The importance of the clutch
In order to understand the chainsaw in its entirety you need to comprehend the function of the clutch. It is made up of a centre shaft, two weights, and an outer drum. The centre shaft is also part of the engine. In this way with the weights acting upon the crankshaft when the crankshaft turns so does the engine. The role of the fine weights is also to keep all working parts in their relevant places. Just outside of the clutch’s outer drum, there is a sprocket that meshes with the chain and triggers it into motion. It is the clutch which gets the power and energy to the chainsaw blade and also regulates the movement of the chain. This can be a very useful safety facility if the operator decides to idle the machine for a short period. In the same way, when the operator triggers the engine into life again, it is the clutch which re-introduces the chain, engages the motor and kicks it back into motion.
When the crankshaft spins it drives the piston up and down. The piston in a chainsaw motor has three functions. Moving back and forth and collecting power; acting as a compressor for the fuel-air mixture; and, as I stated earlier it also acts a valve. There are no valves in the engine. There is no need because the piston commits to this role by letting the exhaust out, and the fuel and air in.
Fuel and ignition
The piston creates the compression which in turn in a petrol model sucks the fuel out of the tank and is drawn into the carburettor. The carburettor plays the important role of mixing the fuel with the outside air. The reaction takes place when the fuel passes over the spark plug, is the production of an electric charge. A spark is a result when the two meet and the fuel is ignited. This action has to be timed correctly and the clever little element that fulfils this job is the flywheel. Within the flywheel is a magnet that aligns itself with the similar magnet on the ignition module, and it is only at this time that the electric charge is triggered to start running towards the spark plug. The air filter sits above the carburettor and cleans any air before it reaches the carburettor. The muffler vents out all expanded exhaust.
Starting your chainsaw for the first time
You need to ensure the saw remains lubricated so add the relative amount of oil to the vessel at the base of the saw. The next thing you need to do is create correct fuel mixture by mixing the two stroke oil (for a two-stroke engine) with the petrol. A special mixing bottle which is available from all good DIY stores will show clearly on the side the correct measurement. You need 40 parts oil to one part petrol. Shake your mixture together to ensure the two liquids have mixed well.
After pouring the fuel into the tank you need to make sure that the ignition switch is in the up position (which is on) and the ignition wire is pulled out to trigger the motion of the engine.
Electric and battery operated models are both push start so they are a great deal easier to get going. However, you can also get push button start for smaller petrol models on the market now.
Keeping your chainsaw in good working order
There is no doubt that an electric or cordless chainsaw is easier to look after than a petrol model. They are smaller and not so powerful so you do not have to constantly check that the motor, spark plug or casing has been upset by use. Also, there is no need to continually see to changing fuel and oil levels. However all models need to be cleaned regularly, the blade needs to be sharpened and tested for tightness, and a regular visit to a dealer for servicing is greatly recommended.