Carburettor; Description; Design - Husqvarna 560XPG Workshop Manual

7.20 Carburettor

WARNING!
The fuel used in the chain saw has the
following hazardous properties:
1. The fluid and its vapour are
poisonous.
2. Can cause skin irritation.
3. Is highly inflammable.

7.20.1 Description

The figures accompanying this description do not
correspond with the carburettor on the chain saw.
They show only the principle of design and function.

7.20.2 Design

The carburettor is based on three sub-systems:
• Pump unit, A.
• Metering unit, B.
• Mixing unit, C.
In the pump unit A, fuel is pumped from the fuel tank
to the carburettor's metering unit. One side of the
pump diaphragm is connected to the crankcase and
pulses in time with the pressure changes in the
crankcase. With the help of inlet and outlet valve in
diaphragm, the fuel is transfered through a filter
screen to inlet needle. See figure 27.
The fuel control unit is attached to the metering unit,
B. Here the correct quantity of fuel is adjusted for the
actual speed and power output. See figure 28.
The mixing unit C houses the choke, the throttle
valve and the diffuser jets. Here air is mixed with the
fuel to give a fuel/air mixture that can be ignited by
the ignition spark. See figure 29.
Fig 27
Fig 28
Fig 29
A
B
C
29
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