Engine size
The volume of the engine of a gasoline saw (see "Power source"). On the one hand, the power and performance of the tool depend on this indicator, on the other hand, its weight, price and fuel consumption. Accordingly, it is necessary to choose a model taking into account the specifics of the planned work, and it does not always make sense to chase large volumes. In particular, for simple household tasks, an engine capacity of about 40 – 50 cm3 is considered quite sufficient, and in professional models this figure can exceed 100 cm3. More detailed selection recommendations can be found in special sources.
Power
Saw motor power in watts. For petrol tools (see "Power Source"), horsepower is additionally indicated, see below for details.
The higher the power, the better the tool is suitable for voluminous work and hard materials, the greater the depth of cut it can provide and the easier it can cope with significant loads. In addition, for different types of saws and different types of materials, the actual power values \u200b\u200bcan also be different. For example, a power of
2.5 – 3 kW is actually the limit for
chain saws, but in
chain saws this is an average figure, among such tools there are models of
3 – 4 kW and even
more. Detailed selection recommendations for various cases can be found in special sources.
Power
The power of the saw engine expressed in horsepower (hp). This designation is traditionally used in gasoline models (see "Power Source") along with watts; 1 HP ≈ 735 W.
For more information about power, see the paragraph of the same name above.
Idle speed
The speed of rotation of the engine in a saw with an internal combustion engine (see "Power") with no load on the blade and with the speed controller fully released (set to minimum). Theoretically, the lower the idle speed, the lower the fuel consumption without load (ceteris paribus); however, the difference between modern chainsaws is usually so insignificant that this parameter is more of a reference than a real practical value.
Bar/blade size
The largest tyre size (in chain saws) or disc (in circular saws and some others, see "Device") that is allowed for this tool. Tyres are sized by working length, rims by diameter.
A larger bar/wheel allows for deeper cuts but requires more powerful motors. Therefore, this parameter cannot be exceeded — this can lead to an overload of the engine with all the corresponding troubles. However, in many models with a disc it is physically impossible to install a nozzle with a diameter larger than the maximum allowable.
Also note that saws with similar bar/blade sizes may differ in maximum depth of cut (mostly due to differences in design or power). As for the specific dimensions, they depend on the type of saw (see "Device"). For example, large discs of
450 – 500 mm are found exclusively in stationary chain saws, the maximum figure for cutting models is
400 – 450 mm, for trimming —
300 – 350 mm, and sizes of
500 – 550 mm or
more clearly indicate that speech It's about a chainsaw chainsaw bar. Detailed recommendations regarding the choice of a tool for a given size can be found in special sources.
Chain speed
The maximum speed of the chain relative to the material that a saw of the appropriate design can provide (see "Device"). Higher speed allows to achieve faster and cleaner cuts, but requires more engine power; low speed, in turn, reduces productivity, but allows you to achieve good traction with a relatively low engine power. More detailed recommendations regarding this parameter can be found in special sources.
Noise level
The noise level produced by the saw during operation. Note that this parameter is rather approximate, because in fact, the “loudness of the work” depends not only on the tool, but also on the material being processed and the characteristics of the environment. Nevertheless, the data given in the characteristics make it possible to assess the comfort of working with the tool. The lower this indicator, the less discomfort the noise will cause, and at high values, even special hearing protection may be needed.
Note that the noise level is usually measured in decibels, and this unit is not linear: for example, a difference of 3 dB corresponds to a difference of 2 times, 10 dB — to 10 times. Therefore, it is easiest to evaluate the noise level using comparative tables. Here is a simplified version of such a table for the range in which modern saws operate:
70 dB — loud conversation of several people in close proximity;
75 dB — a cry in the immediate vicinity;
80 dB — truck engine, mechanical alarm ringing;
85 dB — loud scream;
90 dB — freight car at a distance of 7 – 10 m;
95 dB — subway car at a distance of 7 – 10 m;
100 dB — industrial shop;
110 dB — tractor engine;
120 dB — demolition hammer, thunder from a close lightning strike (pain threshold of auditory perception).
