Subaru 1600 Service Manual page 309

l __
AUTOMATIC TRANSMISSION AND DIFFERENTIAL
2) 4-wheel Drive (4WD)
If the pushbutton on the selector lever
is set to the 4WD position from the
FWD position, the transfer valve opens
the circuit to the transfer clutch as the
solenoid is activated, and, at the same
time, the green 4WD pilot lamp illumi-
nates on the meter panel.
The line pressure, led through; transfer
pipe .... intennediate case .... rear drive
shaft, connects the transfer clutch
(hydraulic clutch).
The power is branched to the front
and to the rear on the front hypoid
pinion. The power branched to the
rear from the shaft end of the pinion
is led through; transfer drive shaft
.... transfer gear .... transfer clutch ....
rear drive shaft .... propeller shaft ....
rear differential, and transmitted to
the rear wheels.
These characteristics have been estab-
lished as being necessary to transmit
the power from the engine to the rear
wheels. If an excessive brake torque is
created on the front and rear wheels in
a tight cornering operation, the trans-
fer clutch acts as a torque limitter
(that is, the clutch slips), and weakens
the braking torque, and also protects
the driving members. As shown in the
characteristic curve in the figure, the
torque limiting function is more effec-
tive when the line pressure is lower
(that is, when the throttle opening is
smaller).
3) Characteristics of Transfer
Clutch
The line pressure is applied to the
transfer clutch, and the clutch capa-
city varies, like the other hydraulic
clutches, with the throttle opening
and vehicle speed, as shown in the
characteristic curve in the figure.
Transfer (4WD)
Torque converter
r--------,
Oil pump' ,
I I
I
I
Lubrication
of rear
-F=:=::;=+--+f:""""'I1-
portion --~~~-
I
(clutch)
x
Oil
cooler
Lubrication
of front
portion
(planetary
one-way
clutch)
X :
Drain
: } : Restriction
,
J~~b'
I
I
I
I
I
I
I
I
I
I
: Transfer valve
I
L _ _ _ _ _ _ _ _
J
1..:::==
Manual valve
-+
(line pressure)
A13-407
Fig. 7-12 Hydraulic circuit in 4WD mode
Torque converter
Oil pump Rear dr i ve shaft
/
Front hypoid pinion Transfer drive shaft Extension case
A 13-408
Fig. 7-13 Transmission of power in 4WD mode
o 490 (5,71)
Throttle
full open
981 (10,142)
A13-409
Line pressure kPa (kg/cm
2
,
psi)
Fig. 7-14 Characteristics of the
transfer clutch (before
o
range "cut down")
7-14
II"-,,,_~:=::.-=-;},
..
,,~~,"fj"'f
w .... ' ... ffif ... • ... • .......
TF_.,..._-__ . . .
·-1flliii _ _ _ ...
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