KAMAZ 5490, Operation Manual

Page: 204 / 327

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4. Description of pre-heater set-up and operation
The pre-heater runs independently of the truck
engine.
The pre-heater is fueled and powered from the
truck. The pre-heater electric circuit is given in Figure 1.
The pre-heater is an autonomous heater (main
components are given in Figure 2), consisting of:
- Heater (main components are given in Figure 3);
- Fuel pump for fuel supply to the combustion
chamber;
- Circulation pump for forced circulation of
liquid in cooling system through the heat-exchanging
system of the pre-heater;
- Control unit to coordinate operation of the
above-mentioned systems;
- Control panel;
- Wiring harness for connection of the pre-heater
components to the truck systems.
The pre-heater principle of operation is based on
warming-up of liquid in the engine cooling system with
its further forced pumping through the heat-exchanging
system of the heater.
Gases generated because of the fuel blend
combustion in the combustion chamber warm up the
liquid. The heat is transmitted through the walls of the
heat exchanger to the coolant fluid, which in its turn is
pumped through the cooling system of the truck engine.
When the pre-heater is switched on, first of all
there is performed functional test of its components, such
as: flame detector, heat and overheating sensors, pump,
air pump motor, glow plugs, fuel pump and
corresponding electric circuits. In case of nonfailed
status, there starts ignition. Simultaneously the
circulation pump is also activated.
The pre-heater may work in two modes
(programs): «economic» and «nominal». The
«economic» mode is characterized by less power
consumption.
In conformity with the preset program there is
performed purging of the combustion chamber and glow
plug warming-up to the desired temperature (the glow
plug is on for 90 sec). Then, there starts fuel and air
supply and combustion process is initiated in the
combustion chamber. The flame detector controls
combustion of the fuel blend in the combustion chamber.
Operation of the pre-heater is controlled by the control
unit.
The control unit controls temperature of the
coolant fluid and depending on this parameter, there is
chosen full, medium or low duty mode of the pre-heater.
The full duty mode means that the coolant fluid is heated
up to 70 °C in «nominal» program, and up to 55 °C in
«economic» program; in case of overheating more than
70 °C or 55 °C the pre-heater is switched to the medium
duty mode. The medium duty mode means that in both
programs the coolant fluid is heated up to 75 °C; in case
of overheating more than 75 °C the pre-heater is
switched to the low duty mode. The low duty mode