Avtodizel ???-238??, Operating Instructions Manual, Page: 75 / 254

75
GHFAN DRIVE
The engines are equipped with friction fan drive intended for
switching-in and switching-off of the fan in dependence of operational
conditions
Using of friction fan drive allows:
•
To provide optimum engine cooling condition.
•
To decrease the fuel consumption due decreasing of power
loss for fan drive.
•
To increase reliability of engine gear drive due to decreasing
of dynamic load on gears.
•
To provide overcoming of a ford without removing of fan.
•
To reduce the engine warm-up time.
•
To improve the cabin comfort due to better cabin tempera-
ture condition and reducing of noise level.
STRUCTURE AND WORK OF FAN DRIVE
The fan drives can be carried-out with the switch of the me-
chanical type (as spare parts for engines produced before 2003 year),
or with the solenoid valve
КЭМ
32 (for engines producing from 2003
year).
STRUCTURE AND WORK OF FAN DRIVE WITH
THE SWITCH OF MECHANICAL TYPE
The fan drive can work in three modes: automatic one, con-
stantly switching-in and constantly switching-off. The fan drive is con-
trolled with the switch.
The fan on non-acting engine is in switch-off condition. After
engine start the fan may to rotate due to friction in the bearings and in
other mated parts of the coupling with speed of 200
÷
500 RPM.
When the engine temperature condition is close to highest opti-
mum one (+85
0
…+93
0 С
) the oil from switch travels under pressure to
union 13 (fig. 38) of the case 14. Then through the holes in case, radial
holes in bushes 10 and 22 oil arrives driving shaft axial hole 18, and
from here to piston 30. The piston begins to travel, transfering the
force through springs 32 to iron ring, the last presses on plates 4 and 5
taking out the backlash between them. When the driving and driven
plates are mated the driven shaft 25 with fan in assembly begins to
rotate with working speed.