BELARUS-1221.2/1221
В
.2/1221.3 Description and operation
81
The
engine cooling system
is of a liquid
closed type, with forced circulation of the
coolant. The system consists of a cooling
jacket, water pump, radiator, fan with
automatically controlled viscous coupling,
two thermostats, expansion tank, connect-
ing hoses and drain cocks.
Thermal state of the diesel is regulated by
changing the air flow passing through the
cooling system radiator as well as by
means of two thermostats.
The coolant temperature is monitored by
the temperature indicator and light alarm
whose sensors are located in the thermo-
stat covers. The normal heat condition of
the engine corresponds to the coolant
temperature of 80…97°C.
The engine lubricating oil is cooled in an
oil-to-liquid heat-exchanger built into the
engine block. To control the oil pressure,
the sensors of oil pressure gauge and
pressure warning indicator installed in the
heat-exchange pipe tap are used. The
normal engine heat condition as to lubri-
cating oil is within 80…120°C.
The
radiator
is of finned tubular design. A
steam valve in the radiator filler neck
maintains the pressure within 0.045…0.05
MPa (0.45…0.50 kgf/cm
2
), while an air
valve monitors the vacuum within
0.008…0.01 MPa (0.08…0.10 kgf/cm
2
).
The fan runs in the two operating modes:
•
automatic;
•
forced.
The automatic mode is provided through a
viscous friction coupling (12) (refer to Fig.
E-8) as follows: at the coolant temperature
below 80°C the return spring (7) holds the
valve (10) closed; viscous liquid flows over
to the clutch reserve cavity; the driving
(11) and driven (13) disks are rotating with
a gap in-between and, thus, ensure the
fan switched-off state (in this case, the fan
rotational frequency shall not exceed
1,500 rpm).
At the diesel coolant temperature exceed-
ing 80°C, the thermosensitive element
opens the valve (10) acting through the
rod (17) and pusher (9) against the force
of the return spring (7). The viscous liquid
flows over into the head cavity through a
hole in the driving disk and fills in the gap
between the driving and driven disks, with
the result that the disk are engaged, and
the fan is turned on in its normal operating
duty.
Attention:
With the compressor run-
ning, the
forced mode
of fan operation
shall be chosen
.
To switch over the fan to the
forced (con-
tinuous) operation mode
proceed as fol-
lows:
•
screw out the nut (4) of the stop (5) by
4…5 turns (about 5 mm);
•
turn the fan by hand so that the stop (5)
would enter the hole (3) in the driving
disk (11). To lock the driving and driven
disks, press the stop (5) by hand.
Содержание 1221.2
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