M.3
COOLING
SYSTEM
68
mm
STROKE
SERIES
WSM,
01
161
[3]
THERMOSTAT
fi
I
C042F048
I
C042F049
(1)
Seat
(2) Valve
(3) Pellet
(4) Spindle
(5)
Synthetic Rubber
(6)
Leak
Hale
(7)
Wax (solid)
(8)
Wax (liquid)
[4]
RADIATOR
(not included
in
the basic engine)
The thermostat maintains the cooling water
at
correct temperature. KUBOTA's engine uses
a
wax
pellet type thermostat. Wax
is
enclosed
in
the pellet.
The wax
is
solid at low temperatures, but turns liquid
at high temperatures, expands and opens
the
valve.
(A) At low temperatures (lower
than
71°C (1
60°F)).
As the thermostat
is
closed, cooling water
circulates
in
the
engine through the water return
pipe without running to the radiator. Air
in
the
water jacket escapes
to
the radiator side through
leak hole
(6)
of the thermostat.
When the temperature of cooling water exceeds
71°C
(160"F),
wax
in
the pellet turns liquid and
expands. Because the spindle
(4)
is
fixed, the
pellet
(3)
is
lowered, the valve
(2)
is
separated
from the seat
(I),
and then cooling water
is
sent
to the radiator.
(B) At high temperatures (higher than
71°C (160°F)).
I0076F014
I
CO42F050
I
[SI
RADIATOR
CAP
[AI
i
I
001
1F033
I
001
1F034
d
The radiator core consists
of
water carrying tubes
and fins
(3)
at a right angle to the tubes
(2).
Heat of
hot
water
in
the tubes
is
radiated from the tube walls
and fins. KUBOTA's engine uses corrugated
fin
type
core
which
has a
light
weight and
high
heat transfer
rate. Clogging
is
minimized by the louverless
corrugated fins.
(1) Cooling Air
(2)
lube
(3)
Fin
(4) Louverlesr Corrugated Fin
(5)
Louvered Corrugated Fin
The
radiator cap
is
for sustaining the internal
pressure of the cooling system at
the
specified level
88
kPa
(0.9
kgfkmz,
13
psi) when the engine
is
in
operation. The cap consists of a pressure valve
(1)
a
vacuum valve
(2),
valve springs, gasket, etc.
Cooling water
is
pressurized by thermal expansion
of
steam, and
as
its
boiling temperature
rises,
generation of air bubbles
will
be suppressed. (Air
bubbles
in
cooling water lowers the cooling effect.)
[A]
When radiator internal pressure
is
high
[e]
When radiator internal pressure
is
negative
(1) Pressure Valve
(2)
Vacuum Valve
M-17
To Next Page
Loading...
