30
Model Code Page
23. Cooling system
1. 9. 2002
8400--8950 230 6
15. 5. 1996
6
1
2
3
4
5
Viscous fan
(Ø 600, 8 pcs blades)
Picture 3. Viscous fan on 8350, 8400 (model 2001), 8450,
8550, 8750 and 8950.
1. Reservoir (filled with silicone fluid).
2. Heat spring
3. Arm
4. Valve plate (fixed)
5. Coupling
6. Return passage
On the above mentioned tractors the engine cooling fan
has been attached on the thermostatic viscous coupling.
In the fan hub there is a small reservoir for viscous oil. On
the hub there is also a thermostatic valve, which senses
temperature of air which flows through t he radiator.
The fan and the hub are attached on the shaft which is ro-
tated by the engine with the aid of the fan belt. In cold
conditions the fan is free on the hub and does not rotate.
When air which flows thro ugh the radiator has a certain
temperature, the thermostatic coupling allows a little oil to
flow into the fan hub and a this creates a ”fluid drive” which
drives the fan and the amount of cooling air increases.
The fan hub includes a small pump, which continuously
returns viscous oil into the reservoir. When the temperature
lowers, the thermostatic coupl ing closes, fluid flow and the
fan speed decreases.
Note! The viscous fan cannot be repaired, but a damaged
fan must be changed for a new one. The fan functio n can
be verified by warming the engine and by watching when
the fan starts to rotate. On tractors with the viscous fan the
tractor frame front piece is longer.
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