CARBURETTOR
28 – English
Fig.
2
B
Fig. 3
C
Fig. 1
A
Carburettor
!
Description
The diagrams with this description do not show the actual
carburettor on the chainsaw. They serve only to illustrate
the principles of arrangement and function.
Arrangement
The carburettor comprises three sub-systems:
•
Metering unit, A in fi g. 1.
•
Mixing venturi, B in fi g 2.
•
Pump unit, C in fi g. 3.
The metering unit (A) contains the jets and fuel control
function. It is here that the correct amount of fuel for the
given engine speed and power demand is metered.
In the mixing venturi (B), the choke, throttle butterfl y valve
and diff user jets are located. Air is mixed with the fuel to give
a fuel/air mixture that can be ignited by the ignition spark.
In the pump unit (C), fuel is pumped from the fuel tank
to the metering unit. One side of the pump diaphragm is
connected to the crankcase and pulses in time with the
pressure changes in the crankcase. The other side of the
diaphragm pumps the fuel.
WARNING!
The fuel that is used in the chainsaw
poses the following hazards:
1. The fl uid and its fumes are poisonous.
2. Can cause skin irritation.
3. Is highly infl ammable.
